Note: Descriptions are shown in the official language in which they were submitted.
CA 02666435 2012-11-01
77680-96
A METHOD AND SYSTEM FOR CUTTINGS DISPOSAL
ON A CUTTINGS PAD
Field
100011 The present disclosure generally relates to systems and
methods for the
handling and disposing of drill cuttings from drilling operations. More
particularly, the present disclosure relates to systems and methods of
impounding drill cuttings on the surface of drilling sites.
Background
[0002] In drilling operations for the exploration of oil and gas, a
liquid slurry
known as drilling mud is used for maintenance and lubrication of the borehole
created during the drilling operation. Typically, the drilling mud system of a
well includes a mud holding tank at the well surface located on or adjacent to
the drilling rig and a network of pumps, mixers, and mud supply lines. During
drilling operations, drilling mud is pumped from the mud holding tank, through
the mud supply lines, down through the well bore and circulated at a desired
rate, and is returned to the surface of the well bore. The returned drilling
mud
carries with it drill cuttings from the bottom of the borehole produced as
drilling advances. When the circulating drilling mud, along with the carried
drill cuttings is returned to the surface, it is delivered to a screening
device
known as a shaker that serves as a sieve for removing the carried drilling
cuttings from the drilling mud. When the drill cuttings have been removed
from the drilling mud by the shaker, the drilling mud is returned to the mud
CA 02666435 2009-04-14
WO 2008/048901
PCT/US2007/081255
storage tank for reuse. The drill cuttings separated from the drilling mud are
collected and conveyed to storage tanks for treating and disposal.
[0003] The storage and disposal of drill cuttings produced at a drilling
location
may present a number of problems. The drill cuttings removed from the
borehole are typically comprised of shale, sand, hard clays, or shell, and
they
are often coated with, or contain, residual contaminants from the drilling mud
of from the borehole. The drill cuttings and their contaminants present
environmental concerns that must be addressed during their disposal.
[0004] Transporting the drill cuttings from a rig site to a disposal
facility is also
a concern because of the costs associated with transporting the bulky, heavy
cuttings boxes to and from the well location. Additionally, drill cuttings
typically contain oil, petroleum distillates, and other environmentally
unsuitable contaminates and often must undergo some treatment to remove or
render inert any associated contaminates prior to their disposal. Such
treatment
is time consuming and expensive because it is typically conducted away from
the rig location.
[0005] In some drilling operations, new waste management techniques
(e.g.,
closed loop dewatering) now allow onsite drill cutting processing that may
substantially decrease drill cutting volume. At such drilling operations, it
may
be beneficial to dispose of the drill cuttings onsite. Typically, onsite drill
cutting disposal consists of plowing (i.e., land-farming) cuttings into the
land,
such that the cuttings stay on the land during storms. However, such land-
farming methods are only available if the cuttings are found to be non-
hazardous (e.g., contain less than 3000 mg/L of chlorides and/or less than
1000
mg/L of oil) according to the laws of the local governing agency.
[00061 Many localities have separate laws that regulate the disposal of
drilling
cuttings if the drilling operation is located on a wetland. Currently, many
jurisdictions do not allow the land-farming of drill cuttings on recognized
wetlands. Instead, the drill cuttings have to removed and properly disposed of
outside the drill site.
2
CA 02666435 2011-06-07
= 77680-96
100071 In still other jurisdictions, if drill cuttings are found to be
hazardous (i.e.,
contain greater than 3000 mg/L of chlorides and/or greater than 1000 mg/L of
oil) according to the laws of the local governing agency, the drill cuttings
may
be buried onsite. In such a drilling operation, pits may be created at the
drilling
site and the drill cuttings buried therein. Buried drill cuttings are buried
so as
to not cause the pollution of ground water or sub-surface water bearing
formations. To prevent contamination as a result of the buried cuttings, the
pits
may have to be lined, chemicals may have to be injected, and the pits may have
to be covered with earth or other substrate. In many drilling operations, the
burial of drill cuttings is time consuming, potentially environmentally
dangerous, and cost inefficient.
[00081 Accordingly, there exists a need for an environmentally safe and
cost
efficient system and method for disposing of drill cuttings from drilling
operations.
Summary
100091 According to one aspect, embodiments disclosed herein relate to a
method for disposing drill cuttings including transferring a plurality of
drill
cuttings from a drilling location to a disposal site. The drill cuttings may
be
placed as a first layer onto a drilling cuttings pad located at the disposal
site,
and impounded onto the drill cuttings pad.
[0010] In another aspect, embodiments disclosed herein relate to a method
for
disposing drill cuttings including transferring a plurality of drill cuttings
from a
drilling location to an mite processing location. The plurality of drill
cuttings
may then be processed into construction materials, and used at the drilling
location.
3
CA 02666435 2013-08-09
77680-96
In another aspect, embodiments disclosed herein relate to a method for
disposing drill cuttings comprising: transferring a plurality of drill
cuttings from a
drilling location to a disposal site; placing the plurality of drill cuttings
as a first layer
onto a drill cuttings pad located at the disposal site; and impounding the
plurality of
drill cuttings on the drill cuttings pad, wherein the drill cuttings pad is
capable of
preventing residual fluids from contaminating the ground where the drill
cuttings are
placed.
In another aspect, embodiments disclosed herein relate to a method of
disposing drill cuttings comprising: transferring a plurality of drill
cuttings from a
drilling location to a disposal site; impounding the plurality of drill
cuttings into a
monolith; and placing the monolith on a surface at the disposal site.
In another aspect, embodiments disclosed herein relate to a system for
disposing drill cuttings comprising: a drill cuttings dispersal device to
transfer drill
cuttings from a cleaning site to a disposal site; and a drill cuttings pad
located at the
disposal site; wherein the drill cuttings dispersal device moves drill
cuttings from the
cleaning site to the disposal site; wherein the drill cuttings are placed on
the drill
cuttings pad; wherein the drill cuttings are impounded on the surface of the
disposal
site, and wherein the drill cuttings pad is capable of preventing residual
fluids from
contaminating the disposal site where the drill cuttings are placed.
[0011] In another aspect, embodiments disclosed herein relate to a system
for
disposing drill cuttings including a drill cuttings dispersal device for
moving drill
cuttings from the cleaning site to the disposal site and a drill cuttings pad
located at
the disposal site. The drill cuttings dispersal device moves drill
3a
CA 02666435 2009-04-14
WO 2008/048901
PCT/US2007/081255
cuttings from the cleaning site to the disposal site where the drill cuttings
are
placed on the drill cuttings pad and impounded on the surface of the disposal
site.
[0012]
Other aspects of the present disclosure will be apparent from the
following description and the appended claims.
Brief Description of Drawings
[0013]
Figure I is a flowchart of a method of disposing of drill cuttings in
accordance with an embodiment of the present disclosure.
[0014]
Figure 2 is a flowchart of a method of disposing of drill cuttings in
accordance with an alternate embodiment of the present disclosure.
Detailed Description
[0015]
Generally, embodiments disclosed herein relate to systems and methods
for the handling and disposing of drill cuttings.
More specifically,
embodiments disclosed herein relate to systems and methods for impounding
drill cuttings on the surface of a drilling location.
[0016]
Typically, drilling fluids used in drilling operations return from down
hole as a slurry, which includes drill cuttings and other suspended
particulate
matter. Initially, the used drilling fluid may undergo any number of
separation
techniques (e.g., centrifugation, screen, mud cleaners, and shaking) to remove
large drill cuttings from the fluid. While the aforementioned methods may
remove large drill cuttings, other solids and fme particulate matter may
remain
suspended in the drilling fluid. Recent advances in dewatering technology
(i.e.,
coagulation and flocculation) allows further removal of suspended solid
particulates from the drilling fluid. After such separation and dewatering,
the
cleaned drilling fluid may be recirculated to a drilling fluid storage tank
for
eventual reuse in the drilling operation.
[0017]
While the drilling fluid is reusable, the drill cuttings and other solid
particulate matter is generally not reusable. As such, drill cuttings are
often
4
CA 02666435 2009-04-14
WO 2008/048901
PCT/US2007/081255
stored onsite for eventual removal from the drill site. While storage methods
vary, many drilling operations use storage bins, surface storage, pit storage,
or
bagged storage prior to removal from the drill site. During storage,
additional
cleaning operations may be performed on the drill cuttings to decrease the
presence of hazardous drilling waste. Such cleaning operations may include,
for example, mechanical and/or chemical treatment to decrease the presence of
environmentally damaging drilling byproducts such as chlorides and oil.
[0018] After collecting and treating the drill cuttings a drilling
operator has to
choose an appropriate technique for disposal of the drill cuttings. In one
embodiment, the drill cuttings may be transferred from the drilling location
(e.g., a drilling rig or cleaning area) to a selected disposal site. The
disposal
site may be selected based on any number of variables including, but not
limited to, proximity to the drilling location, likelihood of stability,
likelihood
of groundwater contamination, or any other variable that may effect the
convenience, efficiency, or environmental integrity as a result of the drill
cuttings disposal.
[0019] Preferably, the disposal site is located in close proximity to the
drilling
location so as to minimize the distance that drill cuttings have to be
transported.
In one embodiment, the disposal site may be adjacent or in close proximity to
the drilling location. Thus, the drilling location may include the disposal
site.
In such an embodiment, the drill cuttings may be transferred to the disposal
site
by use of a drill cuttings dispersal device (e.g., a bulldozer, dump truck,
crane,
or other mechanical device). Because the distance between the drilling
location
and the disposal site is minimal, costs normally associated with drill
cuttings
transportation may be saved.
[0020] In alternate embodiments, the drill cuttings dispersal device may
be an
automated dispersal apparatus. In such an embodiment, a drilling operator may
program the automated dispersal device to take cuttings directly from the
drilling location, and spread them into a specified configuration onto the
disposal site. This method may be of particular benefit when the disposal site
CA 02666435 2009-04-14
WO 2008/048901
PCT/US2007/081255
is located in close proximity to the drilling location. Because the processes
may be automated, the amount of human labor typically required to transfer the
drill cuttings may be decreased, thereby further decreasing the cost of drill
cuttings transference. Such a method of dispersing the cuttings may also be
beneficial in creating a uniform layer of drill cuttings across the disposal
site.
In certain embodiments, a uniform pattern may increase the amount of drill
cuttings that may be stacked in a given location, decrease the costs
associated
with stacking the drill cuttings, and/or otherwise make the process of
stacking
the drill cuttings more efficient.
[0021] In one embodiment, prior to transferring the drill cuttings to the
disposal
site, the disposal site may be prepared by creating a base layer on which the
drill cuttings will be placed. The base layer may include a non-water
permeable layer of clay along with a coating of caliche to prevent the seepage
of residual fluids from the drill cuttings into the ground. To further prevent
the
seepage of residual fluids, a drill cuttings pad may be placed on the ground
where the drill cuttings will be deposited. The drill cuttings pad may be of
any
material capable of preventing residual fluids from contaminating the ground
where the drill cuttings are deposited. One of ordinary skill in the art will
realize that the drill cuttings pad should be able to prevent the seepage of
residual fluids that may form when the drill cuttings are exposed to
environmental stimuli such as precipitation and/or temperature fluctuation.
[0022] In addition to placing a drill cuttings pad on the ground to
prevent
contamination due to seepage, in certain embodiments it may be beneficial to
construct a trench around the area where drill cuttings are deposited. In such
an embodiment, the trench may be constructed around individual deposition
sites, or around the entire disposal site. In an embodiment including both a
drill cuttings pad and a trench, one of ordinary skill in the art will realize
that
the drill cuttings pad may extend from under the deposited drill cuttings over
the trench. Because the drill cuttings pad is impermeable to water and extends
into the trench, should contaminants leech from the drill cuttings the
6
CA 02666435 2009-04-14
WO 2008/048901
PCT/US2007/081255
contaminants may collect in the trench. In such an embodiment, the pools of
contaminated water may either be evacuated from the disposal site, remediated
onsite, or otherwise handled in accordance with the local laws and regulations
governing the drilling location.
10023] After placing the drill cuttings on the drilling pad at the
disposal site, the
drill cuttings may be impounded on the surface of the disposal site. The
process of impounding the drill cuttings may include piling and/or stacking
drill cuttings into piles such that the weight of the drill cuttings cause the
initial
impoundment. In alternate embodiments, the drill cuttings may be pressed into
the surface of the disposal site by mechanical means (e.g., a bulldozer,
crane,
and/or other oilfield machinery). One of ordinary skill in the art will
realize
that surface drill cuttings impoundment may occur as a result of the weight of
subsequent depositions of drill cuttings pressing down on prior deposited
drill
cuttings. In such an embodiment, environmental stimuli may further enhance
the surface impounding. For example, as rain saturates the drill cuttings, the
drill cuttings may further compress into each other and the surface of the
disposal site. Thus, the environmental conditions such as rain and temperature
variation that hampered prior art disposal methods may actually enhance the
disposal technique of the present disclosure.
[0024] In alternate embodiments, once the drill cuttings have been placed
on
the drill cuttings pad, the drill cuttings may be coated with a paint. One of
ordinary skill in the art will realize that the paint used to coat the drill
cuttings
may be of any composition that enhances the solidification of the drill
cuttings.
Such solidification may include paint that increases weather resistance, water
impermeability, or the likelihood that the cuttings will stay impounded. In
one
embodiment, a latex-based paint may be used to coat the exterior of the drill
cuttings thereby decreasing water permeability and increasing the impounded
drill cuttings resistance to weather. In addition to increasing the stability
of the
drill cuttings, paint may be chosen in aesthetically appropriate colors to
minimize the detracting effect of drill cuttings remaining on the surface. For
7
CA 02666435 2009-04-14
WO 2008/048901
PCT/US2007/081255
example, the color of the paint may include natural tones (e.g., browns and
greens) thereby simulating the colors of nature.
[0025] In alternate embodiments, once the drill cuttings have been placed
in a
first layer, a second layer may be placed on top of the first layer. This
embodiment may be appropriate when the first layer has had time to settle out
and is adequately impounded. By placing drill cuttings in layers, the physical
footprint of the disposal site may be substantially decreased, while the
integrity
of the impounded drill cuttings may be maintained. In certain embodiments it
may be beneficial to paint a first layer of impounded drill cuttings, then
place a
second layer on top of the painted first layer. Because the paint may further
stabilize the first layer, subsequent layers may benefit from the increased
stability of the first layer.
[0026] In still another embodiment of the present disclosure, the drill
cuttings
may be treated with a solidification reagent. For example, a solidification
reagent (e.g., cement, kiln dust, fly-ash, paint, silicon dust, blast furnace
sludge,
or any substance that may increase bonding potential) may be added to the
drill
cuttings to increase the bonding of the drill cuttings. The solidification
reagent
may be mixed into the drill cuttings, or in an alternate embodiment, may be
applied to the exterior surface of the drill cuttings to limit the movement of
precipitation therethrough.
[0027] While the above embodiments are described in relation to systems
and
methods for disposing drill cuttings at a disposal site, alternative
embodiments
of the present disclosure may allow the drill cuttings to be used as
construction
materials. In such an embodiment, the drill cuttings may be transferred to an
onsite processing location. At the processing location, the drill cuttings may
be
impounded into construction materials (e.g., berms, location bases, production
pads, and/or road base). One of ordinary skill in the art will realize that
the
processing location may also include the drilling location. For example, in
one
embodiment, drill cuttings may be taken from a collection area and placed on
the surface of another section of the drill site. The drill cuttings may then
be
8
CA 02666435 2009-04-14
WO 2008/048901
PCT/US2007/081255
impounded on the surface to form a base of another drilling rig.
Alternatively,
the drill cuttings may be impounded at the drill site in the form of road
beds,
berms, or otherwise used in the construction of drilling facilities.
100281 In
alternative embodiments, the drill cuttings may be transferred to a
processing location for eventual distribution of the drill cuttings for use as
road
base at on off site location. In this embodiment, the drill cuttings may be
used
as road base in the construction of typical public and/or private roadways.
Because the drill cuttings will be sealed (e.g., with concrete, asphalt,
and/or tar)
in the construction of the roads, the drill cuttings may be used as road base
without significant cleaning/dewatering.
[0029] In
one embodiment of the present disclosure, the drill cuttings may be
transferred from a drilling location to a disposal site and them impounded
into
a monolith. The monolith may include only drill cuttings, or a mixture of
drill
cuttings and solidification reagent, as discussed above. In
such an
embodiment, the monolith may be of any size such that movement of the
monolith by dispersal and/or other moving devices is possible. After
impoundment into a monolith, the drill cuttings may be placed on the surface
of
the disposal site. In one embodiment, the monolith may be placed on the
surface of the drilling site in a manner to provide benefit to the drilling
location. One such benefit may be placing the monolith to promote water
runoff in a specified direction. Other benefits may include, for example,
placing a plurality of monoliths as a roadbed, as a base layer for a new
drilling
rig, or as construction materials, as described above. To allow the greatest
storage of monolithically impounded drill cuttings, it may be beneficial to
stack
the monoliths in a generally pyramidal shape. Such a shape may enhance water
runoff, impoundment, and provide increased storage potential.
10030]
While the above described embodiments relate to methods for disposing
of drill cuttings, one of ordinary skill in the art will appreciate that a
system for
disposing drill cuttings using surface impoundment is also within the scope of
the present disclosure. In one embodiment a system may include a drill
9
CA 02666435 2009-04-14
WO 2008/048901
PCT/US2007/081255
cuttings dispersal device to transfer drill cuttings from a cleaning (i.e.,
dewatering site) to a disposal site. It may be desirable that the disposal
site is
in close proximity to the cleaning site so as to decrease the cost associated
with
moving the drill cuttings. The system may also include a drill cuttings pad
located on the surface of the disposal site, such that the drill cuttings
dispersal
device may move drill cuttings from the cleaning site to the drill cuttings
pad.
Once on the drill cuttings pad, the drill cuttings may be impounded by any
means known to one of ordinary skill in the art, including, but not limited
to,
compressing the drill cuttings with heavy machinery, allowing water to
impound the drill cuttings, or placing additional drill cuttings and allowing
the
weight of the drill cuttings to impound themselves.
[00311 Referring now to Figure 1, a flowchart of a drill cuttings disposal
method in accordance with an embodiment of the present disclosure, is shown.
In this embodiment, a method 100 for disposing of drill cuttings includes
transferring drill cuttings 101 from a cleaning or storage site to a disposal
site.
Before, during, or contemporaneous with building a base layer with the drill
cuttings 103, the drill cuttings may be treated with a solidification reagent
102,
as described above. Upon building the base layer with the drill cuttings 103,
the drill cuttings may be impounded 104. After impoundment, the drilling
cuttings may be sealed 105.
[0032] One of ordinary skill in the art will realize that in certain
embodiments,
it may be beneficial to allow some time to pass between impounding the drill
cuttings 104 and sealing the drill cuttings 105. The time may allow the drill
cuttings to impound to a greater extent, removing aqueous substrate from the
drill cuttings, thereby providing a more stable base layer. In this
embodiment,
after the base layer has been sealed 105, a second layer of drill cuttings may
be
placed 106 on the base layer. After some additional time, as is determined by
a
drilling operator based, among other things, on the composition of the drill
cuttings, the second layer of drill cuttings may be sealed 107.
CA 02666435 2009-04-14
WO 2008/048901
PCT/US2007/081255
[0033] While method 100 illustrates disposing of drill cuttings by
creating as a
sealed base layer and a second sealed layer, one of ordinary skill in the art
will
realize that any number of sealed or unsealed layers may be used in a given
embodiment of the present disclosure. For example, in certain embodiments,
the base layer may be surrounded by a trench, the base layer may constructed
out of caliche instead of drill cuttings, and/or the drill cuttings may be
placed in
a generally pyramidal configuration.
[0034] Referring now to Figure 2, a flowchart of a drill cuttings
disposal
method in accordance with an embodiment of the present disclosure, is shown.
In this embodiment, a method 200 for disposing of drill cuttings includes
transferring drill cuttings 201 from a cleaning or storage site to s disposal
site.
The creation and/or maintenance of the disposal site may include building a
trench 202 around the area where drill cuttings are to be placed. Upon
transference of the drill cuttings, the drill cuttings may be treated with a
solidification reagent 203, and then placed on a drill cuttings pad as a first
layer
204. Unlike the method of system 100, system 200 includes placing a second
layer of drill cuttings 205 without first sealing the first layer. One of
ordinary
skill in the art will realize that in certain embodiments not sealing the
first layer
may promote better drill cuttings impoundment, thereby increasing the storage
potential of a given disposal site.
[0035] After the deposition of drill cuttings as a second layer, the
drill cuttings
may be impounded 206 in accordance with any method described above. After
impoundment, and waiting a specified interval of time, as described above, the
drill cuttings may be painted 207 with a sealing reagent, such as a latex-
based
paint. After the present disclosure, one of ordinary skill in the art will
realize
that additional options may be available to a drilling operator to further
enhance the disposal of drill cuttings. In one embodiment, method 200 may
further include placing the layers of drill cuttings in a generally pyramidal
shape, building a base layer, placing the drill cuttings as monoliths, or
adding a
dispersal device to automatically place the drill cuttings in appropriate
layers.
111
CA 02666435 2009-04-14
WO 2008/048901
PCT/US2007/081255
10036] In another embodiment of the present disclosure, drill cuttings may
be
transferred from a drilling location to a disposal site. The drill cuttings
may be
stacked on a prepared pad constructed of compacted clay dirt and placed over a
liner (e.g., a plastic liner) to prevent the infiltration of drilling waste
into the
surrounding ground. The perimeter of the pad may be lined with a ditch to
prevent residual drilling waste run-off. The drill cuttings may then be
stacked
and/or mixed with a solidification reagent, as described above, then turned to
expose any liquid drilling fluid remaining to the air, thereby promoting
evaporation. In some embodiments, dirt, lime, or other drying agents may be
added incrementally to promote the drying of the drill cuttings. As residual
drilling fluid evaporates, the drill cuttings may become compacted, thereafter
resembling a mound of dirt. The mound may then be terraformed or otherwise
modified as described above.
[0037] Advantageously, embodiments disclosed herein may allow for greater
efficiency in the disposal of drill cuttings. Because the drill cuttings may
be
disposed on the surface of the drilling/disposal site, the costly and time
consuming step of building a pit in which the drill cuttings may be buried may
be eliminated. Additionally, building trenches around disposal sites, as well
as
placement of drill cuttings pads to help catch the runoff of environmentally
hazardous waste products may better protect the ecology of a drilling
operation.
In certain embodiments, treating surface impounded drill cuttings with a
sealing layer may further prevent the leaching of environmentally hazardous
chemicals into the soil and/or water reservoirs.
[0038] Unlike the inefficient and expensive processes of burying or
shipping
drill cuttings currently used, embodiments of the present disclosure may allow
onsite disposal of drill cuttings. By decreasing the distance traveled in the
disposal of drill cuttings, costs associated with fuel and manpower
requirements are decreased. Further, embodiments disclosed herein may allow
the automation of drill cuttings disposal. Such automation may further
decrease the costs associated with drill cuttings disposal.
12
CA 02666435 2009-04-14
WO 2008/048901
PCT/US2007/081255
[0039] Finally, certain embodiments may advantageously allow the efficient
reuse of drill cuttings as construction materials. Drill cuttings processed
into
construction materials may be used in the building of roads (on-site and off-
site) and/or drilling rig bases. By reusing drill cuttings as construction
materials, the cost of disposal is decreased, as well as the costs associated
with
building and maintenance of the drilling location.
[0040] While the present disclosure has been described with respect to a
limited
number of embodiments, those skilled in the art, having benefit of the present
disclosure will appreciate that other embodiments may be devised which do not
depart from the scope of the disclosure described herein. Accordingly, the
scope of the disclosure should be limited only by the claims amended hereto.
13
