Note: Descriptions are shown in the official language in which they were submitted.
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APPARATUS AND METHOD FOR MOVING DRILL CUTTINGS
The present invention relates to an apparatus and
method for moving drill cuttings and particularly, but
not exclusively, for moving wet drill cuttings produced
in the construction of an oil or gas well or drying wet
drill cuttings before the drill cuttings are moved a
substantial distance and subsequently moving the dry
drill cuttings.
For the US part of this application, the following
should be noted: this application is a continuation-in-
part of U.S. Application Ser. Nos. 10/392,285 filed
03/19/2003, and 10/764,825 filed 01/26/2004, which
applications are incorporated fully herein for all
purposes.
In the drilling of a borehole in the construction of
an oil or gas well, a drill bit is arranged on the end of
a drill string and is rotated to bore the borehole. A
drilling fluid known as "drilling mud" is pumped through
the drill string to the drill bit to lubricate the drill
bit. The drilling mud is also used to carry the cuttings
produced by the drill bit and other solids to the surface
through an annulus formed between the drill string and
the borehole. The drilling mud contains expensive
synthetic oil-based lubricants and it is normal therefore
to recover and re-use the used drilling mud, but this
requires the solids to be removed from the drilling mud.
This is achieved by processing the drilling fluid. The
first part of the process is to separate the solids from
the solids laden drilling mud. This is at least partly
achieved with a vibratory separator, such as those shale
shakers disclosed in US 5,265,730, WO 96/33792 and WO
98/16328. Further processing equipment such as
centrifuges and hydrocyclones may be used to further
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clean the mud of solids. The solids are covered in
contaminates and residues.
The resultant solids, known herein as "drill
cuttings" are processed to remove substantially all of
the residues and contaminates from the solids. The solids
can then be disposed of in a landfill site or by dumping
at sea in the environment from which the solids came.
Alternatively, the solids may be used as a material in
the construction industry or have other industrial uses.
The solids are usually processed on land using methods
disclosed, for example in our co-pending PCT Application,
Publication No. WO 03/062591. This processing equipment
may be arranged near to an oil or gas rig. Alternatively,
the processing equipment may be situated on land away
from a marine based oil platform or distant from a land
based rig. Therefore, the solids have to be conveyed from
the exit point of the shakers, centrifuges and
hydrocyclones to the solids processing equipment. In
certain prior art systems oily drill cuttings are loaded
into vessels, skips or cuttings boxes which are lifted by
a crane onto a supply boat. Alternatively this may, in
part, be carried out by using a ditch provided with a
driven screw to convey the wet solids to storage vessels.
Such a system is disclosed in our co-pending PCT
Application, Publication No. WO 03/021074. Drill cuttings
having processed by a shale shaker can contain
approximately 10% to 20% moisture (oil, water) by weight.
It is now often desirable and/or legislatively
required to transport recovered drill cuttings to a
processing site on shore to remove substantially all of
the oil and contaminates therein so that the drill
cuttings can be disposed of or used in an environmentally
safe and friendly way. Environmental agencies around the
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world are moving towards a "zero discharge" policy from
offshore rigs. Continuous drilling on an offshore oil
rig is common and drill cuttings are stored on the rigs
until they can be transported by ships known as supply
boats which collect the oily drill cuttings and take them
to another site for further processing. There is a need
to efficiently and effectively store the oily drill
cuttings on the rig and also a need to efficiently and
effectively store the cuttings on supply boats. The
solids may have a fluid, such as water, added to them to
form a slurry. The slurry may be pumped into ships,
lorries, skips or bags to be moved to the processing
site. Alternatively or additionally, the wet solids from
the storage vessels may be moved using a compressed gas,
as disclosed in PCT Publication No. WO 00/76889 through
pipes.
The prior art discloses various methods for
transporting low slurry density and low particle density
dry solids and non-continuous high slurry density
transport of high particle density wet material using
continuous positive pneumatic pressure. Many low density
slurries typically have particles mixed with air with a
specific gravity less than 1Ø The prior art discloses
various methods that employ the vacuum transport of high
particle and low particle density solids.
Thus tackling the problem of transporting, buffering
and storing low slurry density, high particle density
material, and particularly, but not exclusively, oilfield
drill cuttings or other oily/wet waste material using
continuous positive pneumatic pressure.
WO 00/76889 discloses a system for transporting
drill cuttings in the form of a non-free flowing paste,
the system comprising a pressure vessel having a conical
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hopper discharge portion having a cone angle sufficient
to induce mass flow. The drill cuttings are stored on a
rig and supply boat in ISO sized storage vessels which
have a conical hopper discharge portion, such that the
ISO sized container vessels can be discharged between
each other on the rig and ship and between the ship and
port. These ISO containers are very tall and the quantity
of drill cuttings stored in them is limited due to the
lower converging portion of the vessels.
German Patent No. DE 40 10 676 discloses an
apparatus for conveying sewage sludge or concrete. The
apparatus comprises a pressure vessel having a feed
opening and a screw conveyor therebelow. Paddles act as
a stirrer and forcibly fill the screw conveyor through an
opening in the pressure vessel. The sewage sludge or
concrete is moved by the screw conveyor into a nozzle
into which compressed air is applied to move the sewage
sludge or concrete along a pipe in a continuous stream
United Kingdom Patent No. GB-A-2,330,600 discloses a
system for transporting oil drill cuttings from a rig to
shore. The system comprises the steps of mixing the oily
drill cuttings with a mud to form a slurry, storing the
slurry in retention tanks on the rig and subsequently
pumping the slurry to retention tanks on a ship for
transportation to shore.
WO 03/021074 discloses inter alia an apparatus for
transporting solid waste materials, the apparatus
comprising: an upstream waste supply means; feed means to
transport waste from the waste supply means to a
pneumatic conveyancing means; which pneumatic
conveyancing means comprises a tube within which waste
material is transferred from the feed means to a
downstream waste collector; wherein said tube is
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associated with at least one blockage sensing device, and
electronic data processing means to process data output
from the blockage sensing device.
WO 82/03066 discloses a method for unblocking
conveying pipes for particulate material, comprising
feeding air to the pipe at spaced-apart positions
therealong in order to reduce the length of the blocking
material.
In accordance with the present invention, there is
provided an apparatus for selectively holding drill
cuttings material, preferably in the process of moving
drill cuttings the apparatus comprising a vessel having
a first opening through which drill cuttings material is
introducible into the vessel and a second opening
through which the drill cuttings material is passable out
from the vessel, characterised in that the apparatus
further comprises movement apparatus, the movement
apparatus comprising a movement member within the vessel
and movable adjacent the second opening to facilitate
passage of the drill cuttings material into the second
opening. Preferably, the movement apparatus is mechanical
movement apparatus.
Preferably, the apparatus further comprises a box
for receiving the drill cuttings material passing through
the second opening, the box having a cuttings outlet for
connection to a conveying conduit. The box may be any
space in which the drill cuttings can fall or be pushed
into on their way into the conveying conduit. The box may
form part of the conveying conduit. The conveying conduit
may be a rigid pipe or a flexible hose, preferably
between 50mm and 200mm in diameter, more preferably 100mm
to 150mm and most preferably approximately 125mm in
diameter.
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Advantageously, the apparatus further comprises a
compressed gas inlet for applying compressed gas to the
drill cuttings to facilitate movement of the drill
cuttings through the cuttings outlet. Preferably, the
compressed gas inlet is substantially in line with the
cuttings outlet. Preferably, the gas is air or an inert
gas such as nitrogen. Advantageously, a balancing
compressed air inlet is located in the vessel to provide
a balancing pressure to inhibit drill cuttings from being
blown back from the box into the vessel during discharge.
The balancing pressure is preferably equal to the
pressure in the box, but the balancing pressure may be
slightly less than or greater than the pressure in the
box.
Preferably, the vessel is a pressure vessel.
Advantageously, the pressure vessel has been tested to
withstand a working pressure of at least 2 Bar, more
preferably, at least 4 Bar and most preferably, at least
7 Bar. Preferably, the apparatus further comprises a vent
valve to prevent the vessel from being over pressurized.
A conveyor conduit is maintained substantially full
thereby facilitating consistent feeding or dosing rates.
The conveying conduit may, in certain aspects, be dosed
with drill cuttings in such a way that the conveying
conduit is full so that the drill cuttings move along the
conveying conduit in one long slug. Alternatively, the
drill cuttings may form a plurality of slugs along the
conveying conduit separated by pockets of pneumatic
fluid. This is controlled by the rate at which the drill
cuttings are released or pushed into the conveying
conduit, which is known as the "dosing rate". The dosing
rate is dictated by, among other things, the consistency
of the drill cuttings, the pneumatic pressure applied to
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the drill cuttings, and the diameter of the conveying
conduit in order to achieve a predetermined conveying
rate. In a preferred embodiment, a conveying rate of
thirty metric tons of drill cuttings per hour are moved
along from the storage vessel into the conveying conduit
and on to a destination.
The drill cuttings stored in the storage vessel
may be dry or may be wet. Wet cuttings contain water
and/or oil. Wet drill cuttings may be free flowing, non-
free flowing, or pasty. Drill cuttings are often wet
after having been processed with shale shakers. The
drill cuttings may be dried by a vortex dryer, as
described herein to produce substantially dry drill
cuttings which, in some aspects, may be free flowing
solids which abide by the laws of Newtonian flow.
Advantageously, the movement apparatus further
comprises power apparatus connected to the movement
member for moving the movement member. Preferably, the
second opening has a length and the movement member
comprises an elongated member preferably, having a length
substantially equal to or greater than the length of the
second opening. Advantageously, the elongate member has
an edge shaped for facilitating movement of the drill
cuttings material to the second opening. Preferably, the
elongate member has a leading edge, which is chamfered to
facilitate movement of the elongate member under a pile
of drill cuttings and an trailing edge designed to catch
drill cuttings to move them towards the second opening,
thus the trailing edge is preferably perpendicular to the
direction of movement of the elongate member, may be
stepped and/or may be concave advantageously a scooping
edge for scooping the drill cuttings into the opening and
most preferably is a sliding frame.
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Preferably, the second opening has a width and the
movement member is movable back and forth across the
width. Advantageously, the movement member comprises a
frame having a control shaft connected to at least one
curved outer perimeter portion. Preferably, the movement
member comprises a frame having an outer perimeter
portion generally eye-shaped. Alternatively, a rack and
pinion system may be employed or a rotating disk having
an arm located on the perimeter thereof to translate
rotational motion into forwards and backwards motion, in
a similar way to a crank in a car engine. Such a sliding
member may be used in a variety of tanks, including, but
not limited to, a mass flow hopper, core flow hopper,
flat bottom hopper, a chisel plane flow-type tank, or a
conical tank.
Preferably, the movement apparatus comprises or also
comprises an auger. The auger may form part of a screw
conveyor and may be any form of screw, which moves drill
cuttings. Preferably, the auger is arranged beneath the
second opening. Preferably, the auger is arranged in a
ditch. The ditch may have a cover for inhibiting ingress
of drill cuttings into the ditch when the apparatus is
not being used for a long period of time. The cover may
be movable with the movement member. The cover may be
perforate or imperforate. Preferably, the box is located
at the discharge end of the auger. Advantageously, the
apparatus further comprises a motor for rotating the
auger. Advantageously,
the apparatus further comprises fingers or which may be
blade like located at the end of the auger for
facilitating release of the drill cuttings from the auger
and preferably facilitate breaking up clumps of drill
cuttings. Preferably, the auger comprises at least one
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blade of constant pitch. Advantageously or alternatively,
the auger comprises at least one blade having a variable
pitch.
Advantageously, the apparatus as claimed in any
preceding claim, further comprising a cover to
selectively cover the second opening. Preferably, the
cover pneumatically seals the second opening.
Advantageously, the cover is made from a screen, and thus
allows gas to pass therethrough. Preferably, the cover is
connected to the movement apparatus and moves therewith.
Preferably, the apparatus further comprises a
central stem and a plurality of fingers or bristles
extending therefrom. Preferably, the stem is movable with
a valve located in the first opening to selectively allow
drill cuttings into the vessel.
Preferably, the vessel has a substantially planar
internal base. The base of the vessel may be planar
and/or substantially horizontal. By using a non-conical
hopper or vessel in certain embodiments in accordance
with the present invention, bridging is inhibited and
reduces as compared to bridging that can occur in certain
conical vessels. In one aspect, the sliding member(s)
is/are substantially flat for sliding over a planar base.
In certain aspects the sliding member is rigid.
Preferably the planar base is circular and is between 1.5
and 4 meters in diameter, and in one particular
embodiment is 2.7 meters in diameter. The planar base or
the lower portion of the vessel may be provided with a
plurality of small aeration ports to allow compressed sir
therethrough to aerate the drill cuttings to facilitate
conveying the drill cuttings through the second opening
or into a ditch if provided.
Advantageously, the vessel has at least one
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substantially vertical wall. Preferably, the vessel has a
domed top. Advantageously, the vessel is generally
cylindrical with a generally circular base, the second
opening extending through the generally circular base.
Advantageously, the first opening has a valve
therein for controlling ingress of drill cuttings. The
valve may be of the type disclosed in GB-A-1,539,079 or
US-A-3,586,383.
Preferably, the first opening has a non return valve
for inhibiting drill cuttings from exiting through the
first opening.
Advantageously, the vessel has two sides which slope
toward each other. The vessel may be of wedge, plane
flow, transition, chisel, plane-flow, pyramid, square or
any other suitable type.
Preferably, the vessel has a conical hopper portion.
Advantageously, the conical hopper portion has a cone
angle and forms a lower section of the vessel and the
cone angle is below a critical value required to achieve
mass flow of the drill cuttings material.
Advantageously, the vessel has a capacity of
between 0.15 cubic metres and 1 cubic meter, such that
preferably, the apparatus is not used for storing drill
cuttings, but is used in the continuous conveying of
drill cuttings. The apparatus may be as small as 0.05 and
0.2 cubic metre.
Preferably, the vessel has a capacity of at least
three cubic metres, such that preferably, this is used
for storing drill cuttings, either on a rig, on a barge,
boat, lorry, train or in a storage area on shore. Most
preferably, the vessel is between ten and thirty cubic
metres and even more preferably between twelve and
sixteen cubic metres.
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Advantageously, the apparatus further comprises a
moisture-content sensor for sensing moisture content of
drill cuttings. Preferably, the apparatus further
comprises a hopper wherein the moisture-content sensor is
located in the hopper. Advantageously, the moisture-
content sensor is located within the vessel. Preferably,
the apparatus further comprises a controller for
gathering data from the moisture-content sensor and means
to divert the drill cuttings in response to the data.
Preferably, the means comprises a diverter valve for
diverting the drill cuttings. Advantageously, the means
comprises a screw conveyor, which preferably has a motor
driving the screw conveyor which can rotate the motor
selectably in a clockwise and counter clockwise direction
in order to reverse the conveying from a first direction
to a second opposite direction.
Preferably, the apparatus further comprises a
storage vessel for storing dry drill cuttings.
Advantageously, the apparatus further comprises a storage
vessel for storing wet drill cuttings. Advantageously,
the storage vessel for storing dry cuttings is the
internal bulk storage vessel of a drilling rig.
Preferably, the storage vessel for storing dry cuttings
is the internal hold of a boat or barge. Preferably, the
storage vessel for storing dry cuttings is a further
apparatus of the invention. Advantageously, the storage
vessel for storing wet cuttings is a further apparatus of
the invention. Advantageously, the storage vessel in
accordance with the present invention is fed using a blow
tank. Alternatively, a pump, for example a positive
displacement pump or a cement pump (or pumps) are used in
addition to or in place of blow tank(s) to move the drill
cuttings, for example from shakers or a ditch or vortex
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dryer to the storage vessels. The floor area and overall
space around shale shakers is often limited and so the
storage vessels or skips for containing the drill
cuttings are often placed relatively far, for example a
tens or hundreds of metres (a few hundred feet), from the
shale shakers.
Preferably, the apparatus is skid mounted.
* * *
The invention also provide a method for conveying
drill cuttings, the method comprising the steps of
loading a conveying line with drill cuttings and applying
a positive pressure to move the cuttings therealong,
characterised in that the step of loading the conveying
line is carried out by a mechanical movement apparatus.
The drill cuttings may be free-flowing paste or a non
free-flowing paste, dry clumps, dry free flowing
particles, damp, a slurry or in any other form.
Preferably, the conveying line is provided with a
compressed gas inlet, the method comprising the step of
supply compressed gas through the compressed gas inlet to
facilitate movement of the drill cuttings along the
conveying line. Advantageously, the mechanical movement
apparatus comprises an auger, the auger rotated to load
the conveying line with drill cuttings. Preferably, the
auger is located in a pressure vessel, the method further
comprising the step of loading the pressure vessel with
drill cuttings whereupon the auger is rotated to load the
conveying line with drill cuttings from the pressure
vessel. Advantageously, the step of pressurizing the
pressure vessel to inhibit drill cuttings from passing
from the auger or conveying line back into the pressure
vessel.
Advantageously, the pressure vessel has an inlet
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opening and a valve located in the inlet, the method
further comprising the step of activating the valve to
selectively allow drill cuttings into the pressure
vessel.
Preferably, the pressure vessel has an inlet opening
and a non return valve located in the inlet, the method
further comprising the step of allowing the drill
cuttings into the pressure vessel, the gas under pressure
and drill cuttings therein prevented from escaping
through the non return valve.
Preferably, the method is accomplished on a boat, or
on an offshore drilling rig.
Advantageously, all cuttings movement apparatus is
in controlling communication with control apparatus, the
method including controlling with the control apparatus
the cuttings movement apparatus.
* * *
The invention also provides a method for storing
drill cuttings in a storage vessel and discharging the
drill cuttings therefrom into a pressurized conveying
line, the method comprising the steps of loading the
drill cuttings into a storage vessel, the method further
comprising the steps of activating mechanical movement
apparatus to move the drill cuttings toward an opening in
the substantially in the storage vessel to facilitate
discharge of the drill cuttings. Preferably, the storage
vessel is pressurized, most preferably, with a pneumatic
gas.
Advantageously, the storage vessel has a
substantially planar base, the opening located in the
substantially planar base. Preferably, the mechanical
movement apparatus comprises a wiper, the method further
comprising the step of moving the wiper to move at least
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some of the drill cuttings toward the opening.
Advantageously, the wiper forms part of a frame, the
method comprising the step of moving the frame to move at
least some of the drill cuttings toward the opening.
Preferably, the wiper comprises finger or bristles to
move at least some of the drill cuttings toward the
opening. Advantageously, the mechanical movement
apparatus further comprises a piston and cylinder, the
method further comprising the step of activating the
piston and cylinder to move the wiper. The piston and
cylinder may be activated by a hydraulic or pneumatic
supply.
* * *
Prior art methods use a cuttings dryer which, when
coupled with a pneumatic cuttings conveying system
reduces waste volumes and liquid content, leading to an
overall reduction in storage volume required and
transportation and disposal costs are also reduced. Due
to dried cuttings tending more towards lead phase when
using a positive pressure pneumatic conveying system, it
is important in certain aspects that any change in dryer
output is acted upon at the earliest opportunity. It is
known to be problematic to convey a product when its
consistency is not uniform. To have a storage tank with
a mixture of dried cuttings and wet cuttings can require
a conveying system to alternate between various modes of
flow, between continuous and discontinuous phase flow.
The flow regime of cuttings within a pipe does not lend
itself to this change as wet cuttings tend towards dense
phase with either a shearing type or plug type flow
whereby the slugs of cuttings act as a pulsatile
regular/irregular moving bed which may fill the entire
cross section of pipe; and dried cuttings tend towards
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suspended flow. The transfer rate is required to be
substantially reduced should this "mixture" of modes of
flow transfer be required. Reduced transfer rates are
not desirable while a vessel is alongside a rig taking on
a load. In order to maximize transfer rates, it is
beneficial to maintain a cuttings consistency within the
storage vessel.
The cuttings discharge from a dryer with a screen
may be significantly altered should the screen "blind,"
hence not allowing the liquid to pass through resulting
in a wet discharge. This is known to happen on occasions
when a change in drilled formation results in a change of
particle size generated at the drill bit.
In certain systems in accordance with the present
invention a wetness meter is used to continuously
monitor dryer discharge. The wetness meter may be based
on the Near Infrared (NIR) principle, where it is known
that several molecular bonds absorb infrared light at
well defined wavelengths. Common bonds are 0-H in water,
C-H in organics and oils and N-H in proteins. The light
absorbance level at these specific wavelengths is
proportional to the quantity of that constituent in the
sample material. Infrared filters within the instrument
sensor generate a sequence of light pulses, one of these
pulses is selected to be at the specific absorbance
wavelength for the constituent required to be measured
while the other pulses are selected so as to determine
the reflectance properties of the material. The light
pulses illuminate the sample being measured with the
reflected light being collected and focused onto a
detector, the electrical signals from the detector are
processed into a ratio to provide a value that is
proportional to the constituent concentration - this
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being in percent or other engineering units, water
content and oil based mud content can thereby be
monitored. This technology is well defined and provides
high accuracy and speed of response to facilitate on-line
measurement and control of the dryer process.
Alternative methods in accordance with the present
invention of obtaining a "wetness" value include passing
the product through an open mesh and measuring the
pressure drop generated. A rise in pressure drop
indicates product adhering to the mesh most likely due to
a rise in the "wetness" value. Dielectric constant based
instrumentation or vibratory sensitive instrumentation
may also be used to monitor change in consistency.
Use of information can minimize the "mixing" of
cuttings with storage vessels. In one aspect a dedicated
storage tank is used if a desired "wetness" value is
exceeded. In one such system a bank of storage vessels
are filled with drill cuttings of a satisfactory
consistency and oily if the desired wetness value is
exceeded, then the flow is diverted to a "wet" storage
tank and an alarm raised such that the operator can then
resolve the situation. In another system in accordance
with the present invention a screw conveyor being used to
feed the conveying system after the dryer may be
immediately reversed in order to feed a dedicated "wet"
tank. In another system in accordance with the present
invention two dryers are used each fitted with a screen
with a different mesh size. Should one dryer blind or
malfunction resulting in a "wet" cuttings discharge, then
the cuttings can be redirected by actuating an
appropriate valve below the dryer feed conveyor in order
to use the alternative dryer. In another system in
accordance with the present invention overall height
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required is reduced through the use of screw conveyors.
The invention also provides a method for processing
drill cuttings, the method comprising obtaining drill
cuttings from at least one of a shale shaker,
hydrocyclone, centrifuge or drill cuttings dryer,
measuring the moisture content of the drill cuttings to
obtain a moisture value, comparing the moisture value to
a predetermined threshold and conveying the drill
cuttings in a dry cuttings route if the moisture value is
below the predetermined threshold or conveying the drill
cuttings in a wet cuttings route if the moisture value is
above the threshold.
Preferably, the dry cuttings route comprises a
feeder apparatus and a pneumatic conveying line, the
method further comprising the steps of loading the drill
cuttings into the feeder apparatus, which feeder
apparatus feeds the pneumatic conveying line with the
drill cuttings. Advantageously, the pneumatic conveying
line is a positive pressure pneumatic conveying line. The
positive pneumatic pressure is applied to push the drill
cuttings through the conveying line. Thus preferably, the
pressure behind the drill cuttings is higher than the
pressure in front of the drill cuttings in order to move
the drill cuttings through the conveying line. The
conveying line may be a rigid pipe or a flexible tube.
Preferably, the pneumatic conveying line leads to a
storage vessel, the method further comprising the step of
conveying the drill cuttings through the pneumatic
conveying line to the storage vessel. The storage vessel
is preferably of the type disclosed and claimed herein.
Advantageously, the pneumatic conveying line leads to a
bulk storage tanks of an oil or gas rig, the method
further comprising the step of conveying the drill
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cuttings through the pneumatic conveying line to the bulk
storage tanks. Preferably, the pneumatic conveying line
leads to a hold of an oil or gas rig, the method further
comprising the step of conveying the drill cuttings
through the pneumatic conveying line to the hold. The
hold may be pressure tight and have its own positive
pressure pneumatic conveying apparatus for removing the
drill cuttings from the hold or the hold may not be
pressure tight and may use a stand alone blow tank,
apparatus of the invention as disclosed herein or vacuum
apparatus, such as that manufactured and sold by The
Fuller Company (now called FL Smidth) for sucking the
drill cuttings from the hold and transferring them to
other transportation means on the port, such as tanks or
storage vessels on trains, barges or lorries. Preferably,
the step of measuring the moisture content of the drill
cuttings is carried out with a moisture sensor located in
the feeder apparatus. Advantageously, the feeder
apparatus comprises a hopper and a pressure vessel, the
step of measuring the moisture content of the drill
cuttings is carried out with a moisture sensor located in
the hopper.
Preferably, the wet cuttings route comprises a
feeder apparatus and a pneumatic conveying line, the
method further comprising the steps of loading the drill
cuttings into the feeder apparatus, which feeder
apparatus feeds the pneumatic conveying line with the
drill cuttings. Advantageously, the pneumatic conveying
line is a positive pressure pneumatic conveying line. The
positive pneumatic pressure is applied to push the drill
cuttings through the conveying line. Thus preferably, the
pressure behind the drill cuttings is higher than the
pressure in front of the drill cuttings in order to move
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the drill cuttings through the conveying line. The
conveying line may be a rigid pipe or a flexible tube.
Preferably, the pneumatic conveying line leads to a
storage vessel, the method further comprising the step of
conveying the drill cuttings through the pneumatic
conveying line to the storage vessel. The storage vessel
is preferably of the type disclosed and claimed herein.
Advantageously, the pneumatic conveying line leads to a
cuttings dryer for further drying, such as a vortex dryer
or a dryer of the type disclosed in GB-A-2,297,702.
Preferably, the drier drill cuttings are then returned in
the method to have the moisture measured. Advantageously,
if a mesh is used in the cuttings dryer, a mesh size
different from the ones used in the apparatus from which
the cuttings were previously processed i.e. shale shaker,
hydrocyclone, centrifuge or drill cuttings dryer in case
the high moisture content of the drill cuttings was
caused by near particle blinding. Preferably, the step of
measuring the moisture content of the drill cuttings is
carried out with a moisture sensor located in the feeder
apparatus. Advantageously, the feeder apparatus comprises
a hopper and a pressure vessel, the step of measuring the
moisture content of the drill cuttings is carried out
with a moisture sensor located in the hopper.
Advantageously, the drill cuttings from the at least
one of a shale shaker, hydrocyclone, centrifuge or drill
cuttings dryer, are feed into a feeder apparatus
whereupon moisture content of the drill cuttings is
measured to obtain a moisture value with a moisture
sensor located therein, the feeder apparatus feeding the
drill cuttings into a pneumatic conveying line, the
conveying line having a diverter valve therein, the
method further comprising the steps of diverting the
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drill cuttings using the diverter valve into a dry
cuttings route if the moisture value is below the
predetermined threshold or conveying the drill cuttings
in a wet cuttings route if the moisture value is above
the threshold.
Preferably, a screw conveyor is located beneath the
at least one of a shale shaker, hydrocyclone, centrifuge
or drill cuttings dryer to receive the drill cuttings,
the screw conveyor comprising a drive such that the screw
conveyor is reversible to convey the drill cuttings in
one direction for a dry cuttings route and in a second
direction for a wet cuttings route.
Advantageously, the predetermined threshold is 1%,
3% or 5% moisture content. Moisture content is comprised
water content and oil content. The ratio of oil to water
on drill cuttings varies greatly, but is often found in
the region of half water and half oil.
The invention also provides an apparatus for
carrying out the above method. The apparatus preferably
comprises a moisture sensor and means for directing the
drill cuttings in a wet cuttings route or a dry cuttings
route. Advantageously, the apparatus further comprises a
controller for obtaining data from the moisture sensor
and comparing the data to a predetermined value and
activating the means according to the data.
* * *
The invention also provides a method for moving
drill cuttings, the method comprising the steps of
loading a conduit with drill cuttings, applying positive
pneumatic pressure to the drill cuttings to push the
drill cuttings through the conduit characterised in that
the positive pressure is applied through inlets at spaced
apart intervals along the conduit for facilitating
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movement of drill cuttings therethrough.
Preferably, the pneumatic pressure in the conduit is
measured at spaced intervals therealong, the pressure
measurements reported to a controller, the controller
controlling the application of pneumatic pressure through
said inlets at spaced apart intervals along the conduit.
Advantageously, the controller switches each inlet at
spaced apart intervals on or off in response to the
pressure measurements. Preferably, the pressure applied
at each subsequent inlet is less than the pressure of the
previous inlet. Advantageously, the tubes to the inlets
at spaced apart intervals along the conduit, wherein the
tubes comprise non-return valves to inhibit ingress of
drill cuttings into the inlets.
Preferably, the pressure to each inlet at spaced
apart intervals is variable, the pressure applied thereto
varied in accordance with the pneumatic pressure in the
conduit is measured at spaced intervals.
Advantageously, the pressure to each inlet at spaced
apart intervals is fixed. For example, the pressure at
the first inlet is 4 bar, 3.5 at the second inlet, 3 bar
at the third inlet, 2.5 bar at the fourth inlet, 2 bar at
the fifth inlet and 1.5 bar at the sixth inlet. Each
inlet may be spaced at a fixed distance along the
conduit, for example every 25m. The distance may decrease
to for example every ten metres across a bend in the
conduit. The inlet may be placed at the elbow of the
conduit.
The invention also provides a feeding apparatus for
loading drill cuttings into a positive pressure conduit
comprising a pressure vessel, an inlet, a valve for
selectively allowing drill cuttings into the pressure
vessel and an outlet leading into a conduit, the outlet
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comprising a bend therein beneath the pressure vessel
characterised in that the bend has a compressed air inlet
in the bend for supplying a positive pressure to push the
drill cuttings therethrough. Preferably, the inlet is
directed horizontally, advantageously in line with the
conduit. Preferably, a further valve is located between
the pressure vessel and the outlet. Advantageously, the
outlet converges through the bend, for example a circular
cross-section outlet converges from 150mm to 125mm
diameter.
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For a better understanding of the present invention,
reference will now be made, by way of example, to the
accompanying drawings, in which:
Figure 1A is a top view of a storage vessel in
accordance with the present invention taken along the
line I-I of Figure 1B;
Figure 1B is a side view in cross-section of the
storage vessel shown in Figure 1A;
Figure 1C is a view taken from a similar point to
Figure 1A, of another embodiment of a storage vessel in
accordance with the present invention;
Figure 1D is a top plan view of an alternative part
for the storage vessel shown in Figure 1A;
Figure 2 is a schematic view of the apparatus of the
invention in use;
Figure 3 is a schematic cross-section view of a
prior art feeding vessel used in the apparatus shown in
Figure 2;
Figure 3A is a side view in cross-section of a
feeding vessel in accordance with the present invention
which may be used in place of the feeding vessel shown in
use in the apparatus shown in Figure 2;
Figure 3B is an end view and Figure 3C is a side
view of the feeding vessel shown in Figure 3;
Figure 4 is a side schematic view of a feeding
vessel in accordance with the present invention;
Figure 5A is a view in cross-section of taken along
line VA-VA of a frame part shown in Figure 1A;
Figures 5B to 5D are alternative shapes for the
cross-section of the frame part for the storage vessel
shown in Figure 1A;
Figure 6 is a schematic view of a storage vessel
arrangement in accordance with the present invention;
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Figures 7A and 7B are top cutaway views of another
embodiment of a storage vessel in accordance with the
present invention, showing steps of operation thereof;
Figure 7C is a top cutaway view of another
embodiment of a storage vessel in accordance with the
present invention;
Figures 7D is a side view in cross-section of the
storage vessel shown in Figure 7C with no drill cuttings
therein;
Figures 7E is a side view in cross-section of the
storage vessel shown in Figure 7A with drill cuttings
therein;
Figure 8A is a side schematic view of an apparatus
in accordance with the present invention;
Figure 8B is a top view of part of the apparatus
shown in Figure 8A;
Figure 9A is a schematic view of a feeding apparatus
in accordance with the present invention;
Figure 9B is an end view of part of the feeding
apparatus shown in Figure 9A;
Figure 9C is a side view of part of the feeding
apparatus shown in Figure 9A;
Figures 10 to 15 are schematic views of apparatus in
accordance with the present invention.
Referring to Figures 1A and 1B, a storage vessel 1
in accordance with the present invention has a generally
cylindrical pressure vessel 2 of circular cross-section
with a substantially circular planar base 3 and a domed
cap 4. The planar base 3 and the domed cap 4 may be
formed integrally or be welded to the wall of the
pressure vessel 2.
The pressure vessel 2 may be made of steel of the
type defined by British Standard 1501 224-49B and may be
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designed to withstand a working pressure of between 1 and
20 Bar, and in one particular aspect 7 Bar. The domed
cap 4 has, optionally, an inlet 5 with a supply hose 6
attached thereto, which in one particular aspect has a
52mm (two inch) diameter, for applying compressed gas
such as air and/or nitrogen and/or another inert gas to
the top of the drill cuttings DC in the vessel. The
domed cap 4 is also provided with a cuttings inlet 7
provided with a valve 8, such as a gate valve or a full
bore ball valve, which may be manually operable or
operable remotely, for example using a stepper motor.
Alternatively, cuttings may be introduced to the inlet 7
by any known system, for example but not limited to, a
conveyor system.
The cuttings inlet 7, in one particular aspect, has
an internal diameter of 125mm (5 inches). The planar
base 3 has an opening 9. The opening 9 may be any
suitable shape as viewed from above and, as shown, is
generally rectangular. A tube 10 has an opening
corresponding to and fixed to the perimeter of the
opening 9 in the planar base 3 to form a pressure tight
seal. The tube 10 may be welded or otherwise formed with
the planar base 3. The tube 10 houses an optional auger
which, in one aspect, is a screw conveyor 11 rotatably
mounted in the tube 10 and driven by a variable speed
hydraulic motor 12.
The motor 12 may alternatively be an electrical,
petrol drive, pneumatic or otherwise powered motor. The
screw conveyor 11 has a shaft 13 and a helical blade 14.
The helical blade 14 has, in one aspect, a diameter of
between 150mm and 600mm (6 and 24 inches), and in one
particular aspect has a diameter of between 350mm and
400mm (fourteen and sixteen inches). The shaft 13 has a
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first end coupled to the variable speed hydraulic motor
12 and a second end rotatably arranged in a bearing 15 in
an end wall 16 of the tube 10. The tube 10 extends
beyond the perimeter of the planar base 3. The helical
blade 14 extends along substantially the entire diameter
of the planar base 3 and extends into a portion of the
tube 10 which extends beyond the perimeter of the planar
base 3, whereupon the helical blade ends. In certain
aspects in which there is no auger apparatus or no
conveyor 11, positive pressure gas in the vessel feeds
the material in the vessel to the discharge opening.
Four, six or more radially projecting fingers 17
(two shown) extending from the shaft 13 (or which may be
connected to the interior of the tube 10) are spaced from
the end of the helical blade 14. The portion of the tube
10 which extends beyond the perimeter of the planar base
3 has a discharge box 18 with a lower chamber 18a, having
a compressed gas supply inlet 19 arranged below the end
of the helical blade 14. The discharge box 18 tapers from
a top portion having a width substantially equal to the
diameter of the tube 10 to a smaller width substantially
equal to the diameter of an outlet 20. The air supply
inlet 19 is directed into the lower chamber 18a of the
discharge box 18 and in line with a cuttings outlet 20.
The cuttings outlet 20 has, in one particular aspect, an
internal diameter of 125mm (5 inches) and is attached to
a cuttings conveying line (not shown) of the same or
similar internal diameter, which may be a flexible hose
or a rigid pipe.
A sliding frame 21 is arranged inside the pressure
vessel 2 on the planar base 3 about opening 9. The
sliding frame 21 may be any desired shape as viewed from
above which assists in moving drill cuttings to the
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opening 9. In one aspect as shown, the frame 21 has two
symmetrical curved members 22 and 23 forming an eye shape
which is arranged on four arms 24 joined to a central
member 25. The curvature of the two symmetrical curved
sections is slightly less than the curvature of the
perimeter of the planar base 3. Outer edges 27 of the
two symmetrical curved sections 22 and 23 and of the four
arms 24 are, in one aspect, chamfered, whereas internal
edges 28 (see Figure 5A) facing the opening 9 are at
right angles to the plane of the planar base 3. The
curved members 22 and 23 have flat bottoms 29. The angle
of the chamfer in certain aspects is between 45 and 20
degrees from the flat bottom 29. This can be seen
clearly in Figure 5A. It is within the scope of the
present invention to have a frame or member sized and
configured for movement across the opening 9 of any
desired shape, for example, but not limited to, a member
402 as shown in Figure 1C or a generally circular frame,
as shown with the frame 21a, Figure 1D. The opening 9 may
be any desired shape with any desired width and length;
and, as shown, may be about the same width as an auger
apparatus located beneath the opening (or the auger
apparatus may be slightly wider than the opening).
A hydraulically actuated piston and cylinder
assembly 26 is joined at one end to the wall or planar
base 3 of the pressure vessel 2 and the other to the
sliding frame 21, to induce movement of the sliding frame
21 over the planar base 3 backwards and forwards as
indicated by the arrow within the confines of the
pressure vessel 2. Alternatively some of the frame
movement apparatus may be positioned exteriorly of the
vessel.
The curved members 22 and 23 may have various
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profiles to accomplish the function of sliding underneath
the drill cuttings DC when moving away from the opening 9
and acting as a rake or scoop to scoop, dig, or move the
drill cuttings into the discharge opening 9. In one
aspect the space around the conveyor 11 in the tube 10 is
maintained substantially full to facilitate maintenance
of a consistent dosing rate dependent on the rpm's of the
conveyor 11 while conveying drill cuttings from the
storage vessel.
An exemplary, but not exclusive, list of
alternatives for the curved members 22, 23 is shown in
Figures 5A to 5D. Figure 5B shows a curved member 22
(the member 23 is similar) having a chamfered front face
31 and a concave rear face 30. Figure 5C shows a curved
member 22 (or 23) having a chamfered front face 32 and a
stepped rear face 33 having a shoulder 34. Figure 5D
shows the curved member 22 (or 23) having a stepped front
face 35 and a slightly angled rear face 36 such that an
acute angle is formed in use between the angled rear face
36 and the planar base 3.
The storage vessel 1, in one aspect, is attached to
a skid (not shown) to facilitate transport of the storage
vessel 1 on lorries, supply boats, train cars and on
offshore and onshore rigs. Te skid may also comprise a
frame to surround the storage vessel 1, which may be a
standard ISO size to facilitate transportation of boats,
trains, lorries equipped with fixings at ISO spacings.
The height of the storage vessel 1, in one particular
aspect, when mounted on the skid is 3.26m, the length of
the skid is 3.95m and the width of the skid is 2.9m. It
should be noted that the height of the vessel is very
small compared with the internal volume.
A pressure relief valve 8a is provided on the
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pressure vessel 2, which is set to between 10% and 20%
above the normal working pressure of preferably 7 Bar. A
removable and/or openable hatch 8b is, optionally, also
provided in the wall of the pressure vessel 2 to allow
access for inspection, servicing and cleaning.
Figure 1C illustrates a storage vessel similar to
storage vessel 1, save that instead of a sliding frame
21, the storage vessel has a rake apparatus 100 and an
associated movement apparatus. Like numerals indicate
like parts. The rake apparatus 100 (or the sliding frame
21, etc.) can be used with any tank or vessel described
herein. The rake apparatus 100 has a member 102 on a
shaft 104 that is moved back and forth above the opening
9 by movement apparatus 110. A mover 112 (for example
any suitable motor engine, or reciprocating mechanism,
for example, but not limited to, a piston/cylinder
assembly like that of Figure 1A) moves the shaft 104 back
and forth to move the member 102 above the opening 9 to
facilitate the movement of drill cuttings down into the
opening 9. Optionally a vibratory apparatus 114 exterior
to the vessel 2 vibrates the shaft 104 to vibrate the
member 102 and/or to induce vibration through the vessel
2 in the drill cuttings. Optionally, a vibratory
apparatus 106 is disposed within the vessel 2 on the
shaft 104 to vibrate the shaft 104 and the member 102 to
facilitate cuttings movement. Optionally a vibratory
apparatus 108 on the member 102 facilitates cuttings
movement.
Referring to Figure 2, wet drill cuttings are
produced by a bank of shale shakers 50 on a drilling rig.
The screened wet drill cuttings fall from the
screens of the shale shakers into a ditch 48. The wet
drill cuttings are moved along the ditch 48 using a screw
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conveyor or belt conveyor or fall directly into a hopper.
Wet drill cuttings are optionally fed into a dryer (not
shown), such as a vortex dryer or a dryer of the type
disclosed in GB-A-2,297,702, the disclosure of which is
incorporated for all purposes herein, to remove a
substantial amount of moisture. This is disclosed in
more detail in co-pending PCT publication number
W02004/083597 (PCT application number PCT/GB2004/000762)
and in co-pending US application number U.S. Ser. No.
10/764,825 filed by the applicant for the present patent,
the disclosures of which are incorporated fully for all
purposes herein. In some circumstances, the moisture
content of the drill cuttings is reduced to between 1%
and 5% moisture by weight and in other circumstances down
to 1% moisture by weight. Typically, "wet" cuttings
contain 5% or more oil content and "dry" cuttings contain
less than 5% oil content.
The wet or dry drill cuttings fall directly into a
hopper 51 of a blow tank 52, shown in more detail in
Figure 3. The blow tank 52 may be of the type disclosed
in GB-A-1,564,311, the disclosure of which is
incorporated fully herein for all purposes. A valve 53,
which may be of the type disclosed in GB-A-1,539,079, the
disclosure of which is incorporated fully herein for all
purposes, is arranged between the hopper 51 and a small
pressure vessel 54 having a capacity, in one aspect, of
approximately 0.3 cubic meters, although the capacity in
other aspects is between 0.1 and 1 cubic meter; or larger
or smaller. The size of the small pressure vessel, in
certain embodiments, is dependent on the space available
near shale shakers, and/or the number of cycles needed to
transfer material, for example at a rate of 30 metric
tons per hour. The small pressure vessel 54 has a
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frusto-conical portion 55. An air inlet 56 is arranged
in an upper part of a wall of the pressure vessel 54 and
a cylindrical portion 57 of circular cross-section is
arranged between the valve 53 and the wall of the frusto-
conical portion 55, leaving a small annular gap 58
therebetween through which air under pressure can pass
from the air inlet 56 into the frusto-conical portion 55.
This aspect is also disclosed in US-A-3,586,383 in the
name of William Trythall, the disclosure of which is
incorporated fully herein for all purposes. A further
valve 59 (which is optional) is arranged at the discharge
end of the frusto-conical portion 55 between the small
pressure vessel and a feed line 60. The further valve 59
may be of the same type as valve 53. The feed line 60
may be a flexible hose or a rigid pipe and, in one
aspect, has an internal diameter of 125mm (5 inches) . In
one embodiment, the further valve 59 may be deleted.
In one aspect, the valve 53 and the further valve 59
cycle substantially out of phase, such that the valve 53
is open to allow the small pressure vessel 54 to be
charged with drill cuttings under gravity from the hopper
51 while the valve 59 is closed to inhibit drill cuttings
from entering the feed line 60. The valve 53 is closed
so that a dose of drill cuttings is trapped in the small
pressure vessel 54. The further valve 59 is opened. In
one aspect air under pressure at between 1 and 8 Bar
passes into the small pressure vessel 54 through gap 58
and applies a positive pressure to the top of the charge
of drill cuttings to push a dose of drill cuttings out
into the feed line 60. The further valve 59 may have a
slight delay in opening to allow pressure to build up in
the small pressure 54 vessel before being opened. The
frusto-conical portion 55 may be at an angle to induce
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mass flow, as is well-known in the prior art, for example
as disclosed in US-A-3,604,758, the disclosure of which
is incorporated fully herein for all purposes.
Alternatively the interior wall of the frusto-conical
section is lined with a friction reducing material, such
as plastic, fiberglass, PTFE or a paint or enamel. The
frusto-conical portion 55 may alternatively be a chisel,
pyramid, wedge, transition or square opening type.
Substantially all of the dose is discharged into the feed
line and then the cycle is repeated. Many cycles per
minute may occur. The feed line 60 leads to the inlet 7
of the storage vessel 1, which is arranged on the
offshore rig 49 or, if it is a land based rig, near the
rig. for example within 100 - 300 meters, although it may
be up to many (for example three or more) kilometers
away.
In use, the storage vessel 1 is vented to
atmosphere, either using a valve or by disconnecting the
air supply line 6 from the air inlet 5. Doses of drill
cuttings enter the storage vessel 1, through the feed
line 60 from the blow tank 52 and gradually fill the
storage vessel 1. The storage vessel 1 can, in one
aspect, store up to twelve cubic meters of drill
cuttings, cut may, in other aspects, be sized to store
between five and twenty cubic meters. Once the storage
tank 1 is full or near full, a valve (not shown) in the
feed line is operated to divert the doses of drill
cuttings to another storage vessel 61. Alternatively,
the feed line is disconnected from cuttings inlet 7 and
connected to the cuttings inlet on a further storage
vessel 61. Several storage vessels may be arranged to
form a bank 62 of storage vessels.
At a convenient time when the supply boat or vehicle
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to transport the drill cuttings is in close proximity to
the bank of storage vessels 62, for example when a supply
boat 64 is moored to or within three or four hundred
meters of the offshore rig, one end of a flexible hose 63
is connected to one of the storage vessels 1, 61. The
other end of the flexible hose 63 is connected to at
least one storage vessel 65 in a bank of storage vessels
66 on the supply ship 64. The storage vessels 65 are, in
one aspect of the type described with reference to
Figures 1A to 1D. Floatation collars 67 may be provided
on the flexible hose 63 to inhibit the hose from sinking
into the sea.
An air supply provided by a compressor (not shown)
under approximately 7 Bar and in another aspect 4 Bar is
provided through air supply hose 6 through air inlet 5
into a space in the pressure vessel 2 provided above the
surface of the drill cuttings. The variable speed
hydraulic motor 12 is activated to drive the screw
conveyor 11. A supply of air, for example under
approximately 7 Bar or slightly less, is supplied through
an air supply inlet 19 in the discharge box 18. The same
or a slightly lower pressure in the lower chamber 18a of
the discharge box 18 than the pressure applied above the
drill cuttings inhibits movement of drill cuttings being
pushed back from the screw conveyor 11 back into the
pressure vessel 2. The hydraulic piston and cylinder 26
is activated to move the sliding frame 21 backwards and
forwards to facilitate movement of the drill cuttings
into opening 9. The chamfered edges on the sides of the
members 22, 23, 24 of the sliding frame 21 ensure that
upon movement away from the opening 9 the components of
the sliding frame slide under the drill cuttings and upon
movement towards the opening 9, the opposed right angle
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or scoop profile surfaces pull the drill cuttings towards
the opening 9. The drill cuttings move through opening 9
into the screw conveyor 11 which moves the cuttings along
towards the lower chamber 18a of the discharge box 18.
Towards the end of the screw conveyor, a double helix
blade may be arranged to facilitate break up of the drill
cuttings. Fingers 17 may also be provided to facilitate
break up of the drill cuttings which then fall into the
discharge box 18 and are propelled through the opening 20
into flexible hose 63 into storage vessel 65 on the
supply boat 64.
The supply boat then transports the loaded bank of
storage vessels 66 to shore. The storage vessels may be
lifted off the supply boat 64 and placed on train cars,
flat bed lorries or directly into a processing plant.
Alternatively, the drill cuttings can be discharged in
the same way as described above in relation to moving the
cuttings from an offshore rig to the supply boat 64.
An alternative feeding vessel 70 is shown in Figure
16 which may be used in place of the blow tank 52 shown
in Figure 3A. The vessel 70 has a cuttings inlet 71
leading from a hopper or other vessel (not shown), into a
pressure vessel 72 through a fill valve 73. The lower
end of the pressure vessel 72 is provided with a frusto-
conical portion 74 which leads to a discharge opening 75.
The discharge opening is provided with a discharge valve
76 for selectively opening or closing the opening 75.
The discharge valve 76 and the fill valve 73 are in a
fixed relationship by a piston 77 which extends from the
discharge valve 76 through the fill valve 73 to an
actuating cylinder 78. The piston 77 may be actuated
pneumatically, hydraulically or using a stepper motor to
open and close the fill valve 73 and the discharge valve
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76, which are arranged so that they operate substantially
out of phase. An air supply inlet 81 is arranged in the
top of the small pressure vessel 72 for supplying air
under pressure, for example of approximately 7 Bars,
although it may be supplied at a pressure between one and
ten Bars. Aeration ports 79 are provided in the wall of
the frusto-conical portion 74 to inhibit sticking of the
drill cuttings to the walls and to inhibit bridging of
the drill cuttings around the discharge opening. Fingers
or bristles 80 extend radially from the piston 77 within
the small pressure vessel 72, which are moved up and down
in concert with the valves to brush any drill cuttings
stuck to the walls or in the form of a bridge about the
discharge opening (but for the bristles 80 the tank 70 is
like a prior art tank).
In use, the fill valve 73 and the discharge valve 76
cycle substantially out of phase, such that the fill
valve 73 is open to allow the small pressure vessel 72 to
be charged with drill cuttings under gravity from the
hopper 51 while the discharge valve 76 is closed to
inhibit drill cuttings from entering feed line 60. The
fill valve 73 is closed so that a dose of drill cuttings
is trapped in the small pressure vessel 72. The
discharge valve 76 is opened by actuation of the piston
77, which closes the fill valve 73. Air under pressure,
for example at between 1 and 8 Bar, passes into the small
pressure vessel 72 and applies a positive pressure to the
top of the charge of drill cuttings to push a dose of
drill cuttings out into the feed line 60. The valves may
cycle several times per minute with a relatively small
pressure vessel. With a pressure vessel of 0.3 cubic
metres, the valves will cycle once or twice every minute
or every two minutes. The feed line 60 (as in Figure 2)
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leads to the inlet 7 of the storage vessel 1, which is
arranged on the offshore rig 49 or, if it is a land based
rig, near the rig, for example within 300 meters although
it may be up to three or four kilometers away. Venting
is provided as needed via a vent line 82.
This type of feeding vessel 70 was manufactured by
Klockner-Becroit and shown and described on pages 290-291
of the text book entitled "Pneumatic Conveying of Solids
- a theoretical and practical approach" by Klinzing and
Marcus, published in 1997.
Figure 6 illustrates a system 150 which provides
improvement to systems and apparatuses as disclosed
herein, as well as with systems disclosed in: U.S. Patent
6,702,539 issued March 9, 2004; Great Britain Application
No. 9913909 filed June 16, 1999; U.S. Application
10/018,124 filed as application PCT/GBOO/02158 on June
14, 2000; and European Patent EP 1,187,783 B1, published
Sept. 24, 2003.
Drill cuttings flow in a pipe 157 into containers
151. Each container 151 has a lower conical-shaped
portion 155 with a lower opening 158. Adjacent each
opening 158 is an apparatus 160 (which is like any
apparatus or system disclosed herein to facilitate the
movement of drill cuttings from a tank or vessel, for
example, but not limited to, the apparatus disclosed in
Figures 1A to 1D, for example with a movable frame 21
and/or a movable member 102 and the associated powered
movement mechanisms. The apparatuses 160 move drill
cuttings into a pipe 159 (for example like the pipe 19,
U.S. Patent 6,702,539) from which the drill cuttings can
be introduced into any suitable tank or container for
transport, such as storage containers 1 or the containers
31 shown in US-A-6,702,539. The containers 31 of US-A-
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6,702,539 may have an apparatus like the apparatus 160 to
facilitate cuttings movement.
Optionally, compressed gas (for example air and/or
nitrogen or another inert gas) may be introduced into the
vessels 151 with or after drill cuttings flow into the
vessels 151 in the line 157. Optionally compressed gas
is introduced in a line 161 into the vessels 151 for
application to and/or above the drill cuttings as
previously described and/or referred to for any
embodiment described herein. Optionally compressed gas
is applied in lines 162 to the apparatuses 160 as
described above in the system of Figure 1A. Optionally,
compressed gas may be applied to the interior of the line
159 with one or more apparatus 163 to facilitate the flow
of the drill cuttings material through the line 159.
Each apparatus 160 may, optionally, have a movement
member (for example like frame 21 or member 102) to
facilitate movement of drill cuttings from the vessels
151.
Figures 3A to 3C illustrate a feeding apparatus 470
to feed cuttings (for example from shakers or dryers to
storage vessels), which has a pressure vessel 472 with a
non-conical lower portion 474 which has two sloping sides
475. In certain aspects the pressure vessel 472 has a
capacity of between 0.15 cubic meter and 1 cubic meter,
and in one particular aspect 0.33 cubic meter. Drill
cuttings enter the pressure vessel 472 from an upper
inlet hopper 476 through an opening 477. An inlet valve
478 (for example a dome valve) selectively controls the
entry of drill cuttings into the pressure vessel 472 and,
in one aspect, provides a pre-selected dose of drill
cuttings, for example, in one aspect 0.15 cubic meter to
1 cubic meter, and in one particular aspect 0.3 cubic
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meter.
Optionally, a movement member 482 (for example,
like the movement member 102 or frame 21 described above)
is movable by movement apparatus 484 (shown
schematically; for example any movement apparatus
disclosed herein) to facilitate the movement of drill
cuttings to and through the opening 479 and from the
vessel. Optionally, an auger apparatus 480 (for example
as any auger apparatus described herein and, in one
aspect, like the conveyor 11, Figure 1A) may be used with
the vessel 472.
Figures 7A, 7B and 7E show a storage vessel 200 in
accordance with the present invention which has a
pressure vessel 202 (for example, like the storage vessel
2, Figure 1A) with a domed top 204, a generally
cylindrical wall 206, and a floor 208. Drill cuttings
220 are fed into the vessel 202 via an inlet 210 flow
through which is controlled by a valve 212. Valve 212 may
simply be a flapper non-return valve which allows drill
cuttings into the pressure vessel 202 but does not allow
drill cuttings or air under pressure from escaping the
pressure vessel 202. Optionally, compressed gas is
introduced through a gas inlet 214.
A frame 230 (for example similar to the frame 21,
Figure 1A) slides over the floor 208. The frame 230
includes a solid closure portion 232, but which may be
perforated or made of screen. The closure portion 232
selectively closes off an opening 234 in the floor 208
which is located above a screen conveyor 236 (like the
conveyor 11, Figure 1A) which is rotatably mounted in a
tube 240.
As shown in Figure 7A the closure portion 232 closes
off flow, inhibits or reduces flow to the screw conveyor
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236 when movement apparatus 250 is in the fully retracted
position. This closed position is assumed when the
storage vessel 200 has drill cuttings being stored
therein, for inhibiting drill cuttings from sitting in
the screw conveyor tube 240. It is possible if drill
cuttings sit in the screw conveyor 236 for too long a
period of time that the drill cuttings can set and
inhibit or prevent the screw conveyor from rotating when
discharging the drill cuttings commences. This closed
position is also assumed when the storage vessel 200 is
empty so that drill cuttings are inhibited from falling
into the screw conveyor 236 and becoming compacted in the
screw conveyor 236. As shown in Figure 7B, the frame 230
has been moved by the movement apparatus 250 (like any
movement apparatus disclosed herein) and the opening 234
is no longer blocked and receives material flowing down
from the vessel 202. Cuttings flow from the vessel 202
to a cuttings discharge end 242 of the tube 240 is
facilitated by the screw conveyor 236.
As shown in Figure 7E by arrows 263, the conveyor
236 can be run in reverse to circulate cuttings within
the vessel 202 to produce a more homogenized mass of
cuttings. The arrows 264 indicate rotation of the
conveyor 236 in the direction resulting in cuttings
moving from the vessel 202.
Optionally, the tube 240 may have an inclined end
plate 247 to facilitate cuttings movement toward the
conveyor 236 and, when the conveyor is run in reverse, to
facilitate cuttings movement into and within the vessel
202. Optionally, the tube 240 has an inclined end plate
248 near the tube's discharge end which urges material
down into a discharge chamber 245 and out of the tube
240. Optionally, compressed gas is supplied to an inlet
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243 to promote the movement of drill cuttings from the
discharge chamber out the discharge end 242 of the tube
240.
As shown in Figures 7C and 7D a storage vessel 500
has a pressure vessel 502 (for example like the storage
vessel 2, Figure 1A) with a domed top 504, a generally
cylindrical side wall 506, and a floor 508, further
including a plurality of aeration nozzles 561 through a
floor 508 which inject gas under pressure into a vessel
502 (in certain aspects, upwardly and/or downwardly into
the conveyor 536). The same compressed gas supply that
provides gas to the inlet 514 may be used to provide gas
to the nozzles 561 or a separate compressed gas source
may be used. Air and drill cuttings inlets are not shown
in Figure 7C or 7D. The pressurized fluid through the
nozzles 561 may be at the same or higher pressure than
the pressure used to convey the drill cuttings. By
applying a pneumatic fluid through the air nozzles 562
the drill cuttings are aerated. This is important when
dry drill cuttings are stored in the pressure vessel 502.
The dry drill cuttings are aerated and moved out through
the screw conveyor 536. When the drill cuttings are
aerated, they act more like a fluid and, therefore,
transportation of the drill cuttings is more predictable.
This also can facilitate removal of blockages in the
conveyor and may also be used to purge and clean the
screw conveyor 536 at any convenient time, such as when
the storage vessel 500 is empty. Optionally, the storage
vessel 500 includes a plurality of aeration nozzles 562
which project into the tube 540 and provide gas under
pressure into the tube 540 to promote cuttings movement,
to inhibit cuttings consolidation and unwieldy slug
formation. In one particular aspect there is a plurality
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of aeration nozzles along the full length of the tube
540. When the closure member 532 is in a closed
position, air diffuses past the edges of the closure
member 532 (and, if it is perforated, through any
perforations therein) and aerates the cuttings which are
moving past the frame 530.
A sliding frame (for example like the frame 230,
Figure 7A) in dealing with wet cuttings, dry cuttings, or
cuttings which are moisture bearing, provides discharge
rate control (from the discharge end 242) by controlling
the amount of material that flows into the conveyor 236.
Aerating dried cuttings, for example cuttings dried by a
dryer facilitates cuttings movement by making the
cuttings act more like a fluid and makes transportation
of the cuttings more predictable.
Figure 8A shows an apparatus 600 in accordance with
the present invention for storing and moving drill
cuttings [which may be wet, dry, or moisture-bearing
(damp)] which has an optional vortex dryer 610, feeder
apparatus 620, and a conveying system 650. The vortex
dryer 610 provides drill cuttings to the feeder apparatus
620. The feeder apparatus 620 has a pressure vessel 622
which provides drill cuttings to the conveying line 632.
The feeder system 620 may be, in certain aspects, like
the apparatus shown in Figures 3B or 4 or like any blow
tank or storage vessel disclosed herein.
Referring to Figure 8A, compressed gas to facilitate
cuttings conveyance is supplied from a compressed gas
source 602 in a line 627 to a feeding vessel 622, which
is identical to the feeding apparatus 470 shown in Figure
3A to 3C. Compressed gas from line 627 passes in a line
612 (with flow controlled by a valve 615) to a discharge
box 624. A small amount of compressed gas is applied to
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the top of a pressure vessel 622 through valve 616 to
inhibit cuttings from being blown back into the pressure
vessel 622 from a screw feeder at the bottom of the
pressure vessel 622, which feeds the discharge box 624.
Cuttings discharged from the discharge box 624 are
propelled by the compressed gas into and through a
conveying line 632 from which the cuttings flow to
further processing apparatus (for example another vortex
dryer) or to storage vessel such as the storage vessel 1
shown in Figure 1A or to a prior art cuttings boxes
located on a rig, on shore or on a boat.
A plurality of pressure monitors 640 are spaced-
apart along the conveying line 632, each including a
pressure gauge and in communication with a control
system, for example a PLC control system 680. A
plurality of gas injection apparatuses 690 are spaced-
apart along the conveying line 632 for selectively
injecting gas under pressure into the conveying line 632
as directed by the PLC controller 680. Gas is supplied
in a line 613 to the apparatuses 690. A valve 614
controls flow in the line 613. The valves 614, 615, 616
are in communication with and controlled by the PLC
controller 680. The motorised screw feeder of the
apparatus 600 is in communication with and controlled by
the PLC controller 680.
Each apparatus 690 includes a one way check valve
691 through which air flows into a conveying line 632,
the one way check valves 691 inhibiting drill cuttings
from entering and blocking pneumatic line 613; a
controllable valve 692 that selectively controls flow of
fluid into the conveying line 632; and a regulating valve
693 that selectively allows pneumatic fluid under
pressure through and into the conveying line 632 when the
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pressure differential between the line 613 and the
pressure at the point 640 is less than a predetermined
difference in order to maintain a constant pressure drop
along the conveying line.
The monitoring and control system maximizes
throughput in a safe manner, i.e. avoiding plugging and
pushing solids into a conveying line in an uncontrolled
manner. The use of the apparatus 690 and 640, in one
aspect, ensures that the cuttings are kept "live" and
moving within the conduit 632. The pressures are
monitored at strategic points along its full length. The
pressures observed are maintained by modifying the
cuttings feed rate and/or assist air flow for continuous
(and, in some aspects, optional) performance. To
minimize the overall pressure drop over the length of the
conduit 632, the length and/or density of a conduit 632
is controlled which is in the dense phase mode of flow
whereby it has filled the entire cross section of conduit
The denser the slug, the higher the wall friction,
hence the higher the pressure required to propel the slug
down the conduit 632. Also the relationship of slug-
length-to-pressure required to propel a slug is
exponential; i.e., the pressure required to convey a
series of slugs separated by "cushions" of air is far
less than that needed to convey a single slug whose
length is equivalent to the sum of the lengths of the
series of slugs.
The feeding apparatus 620 doses cuttings into the
conduit 632 in slugs, the size of which are determined by
the screw or auger outside diameter, shaft size and
pitch. The feed rate is directly proportional to the
rotational speed of the screw. Localized aeration within
the conveying/discharge chamber of the screw ensures the
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cuttings are "life" and the speed control/stop/start
facility of the screw controlled by the PLC controller
680 offers close control in the creation of the slugs.
This control is based upon the pressure regime within the
conduit 632 which is heavily dependant upon the mode of
flow.
In one aspect nominal setpoints are used within the
conduit 632 regarding the maximum pressure drop across
the conduit 632, one set at a low value for dilute phase,
for example 2 bar, which is used for dried drill cuttings
and the other for non-dried cuttings which is higher, for
example 4 bar. In one particular aspect, in dense phase,
the drill cuttings move along the conveying line at
approximately 10 m/s; and in lean or dilute phase, the
drill cuttings move along the conveying line at
approximately 30 m/s. The PLC controller 680 ramps up
the screw speed to the speed necessary to feed the
conveying line 632 so that pressure drop is maintained to
a set level between the units 690. For example, with
four units 690 spaced equidistant along the length of a
straight conveying line 632, the conveying line 632 is
dosed with a first dose of drill cuttings from the feeder
620. The air supply 602 is activated and the plug of
drill cuttings moves along the conveying line. The
initial pressure is set to for example 4 bar and it is
expected that the pressure at the end of the conveying
line will be slightly above atmospheric when the plug
reaches the end. The units 690 regulate the pressure in
the line so that there is a reasonably constant pressure
drop between the units 690. The pressure drop is, for
example 0.5 bar between each unit, such that after the
first unit 690 the pressure is regulated at 3.5 bar,
after the second unit the pressure is regulated to 3 bar
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after the third unit the pressure is regulated to 2.5 bar
and after the fourth unit the pressure is regulated to 2
bar so that it is expected that the pressure at the end
of the conveying line 632 is approximately 1.5 bar and
that there is a reasonable degree of certainty in knowing
the plug will discharge from the end of the conveying
line and into a storage vessel. If the pressure drop is
within a certain percentage, for example 30%, and, in one
aspect, 15%, and in one particular aspect, 10% of what
was expected, the regulator opens the line 613 and allows
air under pressure, regulated by regulator 693 to enter
the conveying line at the correct pressure.
A standard PID loop "PID loop" (Proportional-
Integral-Differential) is utilized such that should the
pressure drop overshoot the desired setpoint, the screw
feeder speed is reduced or stalled accordingly. Feedback
from the pressure monitors 640 along the line which are
located strategically slightly upstream of bends/vertical
lifts or any other areas known to create turbulence
within the conduit are used in order to actuate air
assist valves in the apparatus 690 should it be
necessary. An air assist valve is located at a
turbulence point downstream of a pressure monitor and
should the pressure at the monitor go below a given
percentage value compared to the sensor immediately
upstream of it, for example 80%, then air is fed direct
from source 602 via the bypass line 613 which runs the
full length of the conduit 632 into the associated assist
point. The pressure setting for the air assist is set at
for example 90% of the pressure value at the monitor 640
immediately upstream, and if this pressure is reached,
then the assist air is also directed to the next
injection point immediately downstream and so forth.
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Each valve 691 can feed an associated gas injection
nozzle 699 (for example see Figure 8B).
Figures 9A to 9C illustrate a feeder apparatus 700
in accordance with the present invention, which is like
the feeding apparatus 470 shown in Figure 3B, further
incorporating a hopper 720 having a vibratory motor 725
for vibrating the buffer hopper portion 721 and a further
air injector 772 and modified discharge box 753. A
control system 701 is in communication with sensors in
the hopper portion 721 and the pressure vessel portion
740. The hopper 720 comprises the buffer hopper 721; an
optional vibratory motor 722 for vibrating the buffer
hopper 721 and its contents; an expansion joint 722; and
a valve 723 at an exit opening 724 to control the flow of
drill cuttings from the hopper 721 to the storage vessel
system 740. The conveying apparatus 700 is used, for
example, to move drill cuttings from shakers to storage
vessels, and, in one particular aspect, the pressure
vessel 740 only has a storage capacity of about 0.3 cubic
meter.
The pressure vessel portion 740 may be like the
storage vessels shown in Figures 1A, 3B-D, 7A and 8A.
The pressure vessel portion 740 has a vessel 742 which
receives drill cuttings through an inlet 743. A vent
valve 744 selectively vents the vessel 742 and a relief
valve 745 relieves pressure in the vessel 742 at a preset
level. A conveyor 750 conveys drill cuttings from the
vessel 742 to a discharge box 751 and the cuttings exit a
discharge end 752 of a tube 753 to flow into a conduit
(not shown; for example like the conduit 632, Figure 8A).
A motor/gear system 760 rotates the conveyor 750.
Compressed gas from a source 770 supplied gas under
pressure in a line 771 to an inlet 772 on the discharge
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box 753; in a line 773 to an inlet 774 at the discharge
end 752 of the discharge box 753; in a line 775 to an
inlet 776 at the discharge box 751; and in a line 777 to
an inlet 778 of the pressure vessel 742. The inlet 778
may be of very small diameter, as this is simply for
balancing the pressure within the pressure vessel 742
with the pressur in the box 751 or in the discharge end
752. Each line has a one way check valve 779.
Optionally the hopper 721 is mounted on isolation/non-
vibration mounts 782.
All the operational components of the conveying
apparatus 700 are in communication with (see dotted
lines) a controller 701 (for example like the controller
680, Figure 8A).
Each line 771, 773, 777 has an on/off flow control
valve 771a, 773a, 777a respectively (for example like the
valves 692); a pressure regulator 771b, 773b, 777b,
respectively (like the pressure units 690; pressure set
manually or by the control system, the set pressure
effectively sets the maximum working pressure of the
system, for example, 2 BAR for dried cuttings or 4 BAR
for wet cuttings from the shale shakers); and flow
control valves 771c, 773c, and 777c, respectively, which
control the rate of change in pressure (for example, may
be needle valves, orifice plates, or similar devices).
Via the line 777 gas is provided to the vessel 742
at a pressure equal to the pressure of gas provided to
the discharge box 753 in the line 771 and to the gas
provided in the line 773 to the discharge box 751 so that
the pressure drop across the conveyor (screw feeder) 750
is negligible. Therefore feed rate of cuttings from the
system 700 is determined by the rpm's of the conveyor
750. In one aspect gas is input downstream of a
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discharge valve 752a in the line 773. With the discharge
valve 752a closed, the vessel 742 can be vented to the
atmosphere, permitting refilling of the vessel 742 while
cuttings are being conveyed downstream of the discharge
end 752.
The control system shown in Figures 9A to 9C may be
used for any feeder apparatus or storage vessel disclosed
herein.
Figure 10 shows a system 800 in accordance with the
present invention, which has a cuttings dryer 801 which
dries drill cuttings, such as a vortex dryer or a
cuttings dryer of the type disclosed in GB-A-2,297,702.
The vortex dryer 801 may be fed and located immediately
below the discharge end of a shale shaker (not shown) or
at the end of a ditch (not shown) fed by a plurality of
shale shakers (not shown). However, the drill cuttings to
be dried are dried in the cuttings dryer 801 for a set
time or within a limited range of time. Accordingly, if
the drill cuttings are very wet, for example if the shale
shakers have suffered from "near sized particle
blinding", in which case a substantial amount of drilling
fluid would wash over the shaker into the cuttings dryer
with the drill cuttings, some or all of the drill
cuttings will not be sufficiently dry to transport with
the pressure vessel or will simply require further
drying, further processing or to be stored and conveyed
in or from a special storage vessel. Thus, a conveyor
system 802 with augers 803, 804 driven by a motor/gear
system 805 provides drill cuttings selectively to a
storage vessel 810 or to a pressurized feeding apparatus
820, based on measurements by a moisture sensor 821 (or
sensors). Non-wet cuttings go to the pressurized feeding
apparatus 820; if "wet" cuttings are sensed, the augers
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are reversed and cuttings are conveyed to the storage
vessel 810 (which may be like the storage vessel 1) . A
sensor (or sensors) 821 sense moisture content of the
drill cuttings. If the sensor 821 senses "wet" (for
example greater than 1, 3 or 5% moisture content) then
the auger is reversed and moves the cuttings to the "wet"
cuttings storage vessel 810; and, if the cuttings are dry
(for example less than 5% moisture or oil content), the
auger is set in forward motion and the cuttings are
supplied to the pressurized feeding apparatus 820, which
blows the cuttings to a dry cuttings box 825, which may
be like the cuttings storage vessel 1. In one particular
arrangement, once cuttings have moved to the storage
vessel 810, they can then be moved to the dry cuttings
box 825. Optionally (as is the case for any moisture
sensor or sensor apparatus in any system herein) the
sensor 821 may have a protective canopy 821a for
components outside a hopper and a protective canopy 821b
for components 821c within a hopper 822. Such a canopy
821b protects sensor components 821c from drill cuttings
falling downwardly in a hopper. Multiple sensors 821 may
be used spaced apart around the hopper 822 (as is the
case for any system in accordance with the present
invention with moisture sensor apparatus). In certain
aspects, such sensors are efficacious with a drill
cuttings amount that is at least 2.5cm (one inch) thick
and has an area of at least twenty to twenty six square
cm (three to four square inches). Such sensors may
produce continuous readings for more accurate use by a
control system 829 which is in controlling communication
with components of the system 800 as indicated by dotted
lines.
The control system 829 can switch cuttings flow from
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the system 825 (for example for adequately dry cuttings)
to the system 810 (for example for relatively wet
cuttings). In any system herein a first storage
apparatus or a "dry" storage apparatus can be a storage
vessel, the hold of a ship, or a hold or reservoir on a
rig or in legs of a rig. Such storage facility, in
whatever form, may have, in accordance with the present
invention, a positive pressure pneumatic system and a
bottom aeration system for aerating drill cuttings
material from underneath the material (for example
through a perforated bottom plate or member) producing a
dilute phase material which is more easily conveyed. In
one particular aspect moisture content sensors are like
Models MCT 300, MCT 600 and MCT 101-T sensors from
Process Sensors Corporation, Milford, Massachusetts. As
is the case with any pressurized vessel in any system
herein, a cuttings vessel 820a of the system 800 may be,
in volume, between 0.05 m3 to 0.2 m3.
Figure 11 shows a system 830 in accordance with the
present invention in which a conveyor 831 powered by a
motor/gear system 832 feeds drill cuttings to two vortex
dryers 833. Cuttings processed by the vortex dryers 833
are fed by conveyor systems 834 to a hopper 835 of a
feeder system 836 (like the system 820, Figure 10). One
of the vortex dryers 833 has a screen which blinds if the
drill cuttings are "near sized" ("near sized" means the
size of cuttings generated by drilling which have a size
distribution like that of the size of screen mesh
apertures of screens in screening apparatus; near size
particles can become lodged in screen apertures, clogging
a screen), at which point wet drill cuttings flow out of
the vortex dryer. This is noted by a moisture sensor 831
which sends a signal to the second vortex dryer, which
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kicks in, which has a screen with a screen size different
from the first vortex dryer, and therefore can cope with
this size of particle. The system 836 produces processed
cuttings which exit in a conduit 837.
Figure 12 shows a system 850 in accordance with the
present invention similar to the system of Figure 11
which has a conveyor system 851 powered by a motor/gear
system 852 which conveys drill cuttings from shale
shakers, hydrocyclones and/or centrifuges to vortex
dryers 853 which in turn feed dried cuttings via a chute
854 to a feeding apparatus 856 (like the feeding
apparatus 836) which feeds the cuttings into an exit
conduit 857. The vortex dryers 853 have hoppers 854
beneath them which feed the feeding apparatus 856.
Figure 13 shows a system 900 in accordance with the
present invention for a drilling rig R in which drill
cuttings (for example from shale shakers, centrifuges)
flow to an feeding apparatus 906 (like the feeding
apparatus 820, 836, 856) with a vortex dryer 907. The
feeding apparatus 906 processes the cuttings and feeds
them to a storage vessel, which may be of the type shown
in Figures 1A, 1C or 7A). If the reading from the
moisture sensor in the feeding apparatus 906 indicates
that the drill cuttings are dry, a controller (not shown)
diverts the flow of drill cuttings from the feeding
apparatus 906 to either the internal bulk handling
storage units 910 built into the rig R or into the
internal hold 911 in the supply boat B (if a supply boat
is available). If the reading from the moisture sensor
indicates that the drill cuttings are wet, then the
controller diverts the flow of drill cuttings to wet
storage vessel 1 on the rig R or on the boat B. The
internal bulk handling storage units built into the rig R
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and the internal hold in the supply boat B are able to
handle dry bulk material but not wet bulk material. Thus
by assessing the dryness of the drill cuttings, it is
possible to store the drill cuttings in the internal bulk
handling storage units 910 built into the rig R or into
the internal hold 911 in the supply boat B. The wet drill
cuttings can be loaded and stored in a storage vessel of
the type shown in Figure 1 or reprocessed in a cuttings
dryer, such as a vortex dryer or a cuttings dryer of the
type disclosed in WO 2004/000762 and GB-A-2,297,702 and
the moisture re-tested.
Figure 14 shows a system 920 in accordance with the
present invention in which shale shakers 921 feed drill
cuttings material on to a screw or belt conveyor 922
which feeds the material to a vortex dryer 923 which
feeds dried material to a pressurized screw feeding
apparatus 924 (like the screw feeder apparatus shown in
Figures 8A, 9A and 10 to 12). Material processed through
the pressurized screw feeding apparatus 924 exits for
transfer in a line 925. Fluid recovered from the vortex
dryer 923 flows in a line 926 to a holding tank 927 from
which it is pumped by a pump 928 in a line 929 to a
centrifuge 930. Solids from the centrifuge 930 are
conducted in a line 931 for disposal and liquid is pumped
in a line 932 to a holding tank 933. A pump 934 pumps
liquid from the holding tank 933 either in a line 939 to
a mud return system 935 (with a valve 936 closed and
valve 938 open); or back to the vortex dryer 923 in a
line 937 (with valve 936 open and a valve 938 closed).
Figure 15 shows a system 950 in accordance with the
present invention in which a pressurized screw feeder
apparatus 952 selectively feeds drill cuttings material
to dried cuttings storage vessels 953 or to a "wet" tank
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storage vessel 954. A wetness meter 955 located in the
hopper 968 senses moisture content of the drill cuttings
material and controller 960 in communication with the
wetness meter 955, controls a diverter valve 956 so that
adequately dry cuttings go to the storage vessels 953
with flow to the "wet" tank system 954 shut off; and wet
cuttings go to the wet tank system 954 with flow to the
storage vessels 953 shut off. Optionally, each storage
vessel 953 has its own associated diverter valve 957 so
that flow to each box is selectively controlled by the
controller 960.
In certain aspects the pressurized screw feeding
apparatus 952 is like the apparatus in Figures 8A and 26;
the wet storage vessel 954 is like the wet storage vessel
in Figure 10; and the storage vessels 953 are like the
storage vessels in Figures 1B, 3B and 10. The controller
960 controls the motors of each conveyor in the system
950.
In each of the systems of Figures 10 to 15 a
suitable control system controls the various components
and is in communication with the moisture sensors,
valves, conveyors, and motors.
A method for moving drill cuttings from an offshore
rig located in water to a boat in the water adjacent said
offshore rig, said drill cuttings laden with drilling
fluid, the method including feeding drill cuttings from a
drilling operation to a cuttings processor, the cuttings
processor comprising a rotating annular screen apparatus,
processing the drill cuttings with the cuttings processor
producing processed drill cuttings and secondary
material, the secondary material including drill cuttings
and drilling fluid, the processed drill cuttings
including drilling fluid, feeding the processed drill
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cuttings from the cuttings processor to positive pressure
blow tank apparatus, the positive pressure blow tank
apparatus having a tank which receives the processed
drill cuttings from the cuttings processor, feeding the
secondary material from the cuttings processor to
secondary apparatus, and supplying air under pressure to
the tank of the positive pressure blow tank apparatus for
expelling drill cuttings from the tank and propelling the
drill cuttings to tertiary apparatus. In one particular
aspect the secondary apparatus is decanting centrifuge
apparatus, the method further including processing the
secondary material with the decanting centrifuge
apparatus, producing secondary drilling fluid and
secondary drill cuttings. In one aspect, prior to
feeding drill cuttings from the cuttings processor to the
positive pressure blow tank apparatus, the drill cuttings
are fed to mill apparatus to break up agglomerations of
the drill cuttings and then feeding them from the mill
apparatus to the positive pressure blow tank apparatus.
In one aspect, in methods wherein the secondary
apparatus is decanting centrifuge apparatus, the methods
include processing the secondary material with the
centrifuge apparatus, producing secondary drilling fluid
and secondary drill cuttings, recycling said secondary
drilling fluid for reuse in a drilling operation, feeding
said secondary drill cuttings to a mill apparatus for
breaking up agglomerations of said secondary drill
cuttings, feeding secondary drill cuttings from the mill
apparatus to the positive pressure blow tank apparatus;
and/or prior to feeding drill cuttings from the cuttings
processor to the positive pressure blow tank apparatus,
feeding said drill cuttings to mill apparatus to break up
agglomerations of said drill cuttings and then feeding
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said drill cuttings from the mill apparatus to the
positive pressure blow tank apparatus.
A method for moving drill cuttings material, the
drill cuttings material including drill cuttings and
drilling fluid, the method includes feeding the drill
cuttings material to cuttings processor apparatus, the
cuttings processor apparatus including rotating annular
screen apparatus, processing the drill cuttings material
with the cuttings processor producing processed drill
cuttings and secondary material, the secondary material
including drill cuttings and drilling fluid, said
processed drill cuttings including drilling fluid,
conveying with fluid under positive pressure processed
drill cuttings from the cuttings processor to flow
conduit apparatus, applying air under positive pressure
to the flow conduit apparatus to continuously move the
processed drill cuttings therethrough, continuously
moving the processed drill cuttings with the air under
pressure to separation apparatus, and with the separation
apparatus continuously separating processed drill
cuttings from the air.
A system for moving drill cuttings, the system
having movement apparatus for moving drill cuttings,
cuttings processor apparatus for processing the drill
cuttings for feed to tank apparatus, the cuttings
processor apparatus including rotating annular screen
apparatus, tank apparatus for receiving drill cuttings
from the cuttings processor apparatus, flow conduit
apparatus for receiving drill cuttings from the tank
apparatus, pressurized fluid apparatus for applying air
under positive pressure to the drill cuttings and for
continuously moving the drill cuttings through the flow
conduit apparatus and to separation apparatus, and
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separation apparatus for continuously receiving the drill
cuttings through the flow conduit apparatus, the
separation apparatus for separating the drill cuttings
from air.
A method of conveying a paste, the paste including
drill cuttings laden with fluid, the method including
feeding the paste to a cuttings processor, the cuttings
processor comprising a rotating annular screen apparatus,
reducing the weight of said paste with the cuttings
processor by removing fluid from the paste, the cuttings
processor producing produced material that includes drill
cuttings and fluid, feeding the produced material from
the cuttings processor into a vessel, applying a
compressed gas to the vessel to cause the produced
material to flow out of the vessel, the vessel including
a conical hopper portion which, at least during discharge
of the produced material, forms the lower section of the
vessel and the cone angle is below a critical value
required to achieve mass flow of the produced material.
Systems and methods for moving material that has a
low slurry density, (for example with a specific gravity
between 2.3 and 4.0 and, in one aspect, about 2.7 or
lower) and a high particle density, (for example 2
lbs/gallon - 4 lbs/gallon or higher) with a positive
pressure pneumatic fluid, for example air or steam. In
other aspects the cuttings to be treated, for example
from shale shakers, have a specific gravity of 1.8 (1800
kg/m3; 15 lbs/gallon) and certain high density cuttings
have a specific gravity of 2.5 (21 lbs/gallon). In one
particular aspect the material is a slurry that includes
drill cuttings from a wellbore, well drilling fluids,
drilling muds, water, oil, and/or emulsions with the
cuttings present as varying weight percents of the
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slurry. "Slurry density" refers to material from a well
in an air flow and "particle density" refers to the
material prior to its inclusion in an air flow.
In certain aspects systems and methods provide the
continuous or almost-continuous transport of material.
Systems with storage facilities for solids to be
moved and apparatus for mixing heavy solids to be
transported with a pneumatic fluid, for example, but not
limited to, air or steam, at a positive pressure, i.e.
above atmospheric pressure. In one aspect the velocity
of moving solids is reduced using, for example, a
separator apparatus, and then the solids are collected in
collection apparatus (for example tanks, boxes, storage
containers). In certain aspects self-unloading tanks are
used that have a positive pressure solids removal system.
Such tanks may have systems for measuring the amount of
solids in the tanks and providing an indication of this
amount.
In one aspect the apparatus reduces the density of a
slurry of material. Such apparatus includes
decelerator/separator apparatus.
