Note: Descriptions are shown in the official language in which they were submitted.
CA 02578726 2007-03-09
FIELD OF INVENTION =
This invention relates _ to a bottomhole assembly (BHA) for use in well
operations, with particular application to use in drilling with a downhole
drilling motor
and coiled tubing, and the invention relates to related methods of use of a
BHA.
BACKGROUND OF THE INVENTION
The BJ Nowsco directional drilling-using-coiled-tubing (D U C T) is an on-
bottom orientation and steering system for the tool string. The orient-while-
drilling
system provides jovstick drilling. The heart of the system. that which enables
orient-
while-drilling, or on-bottom orientation/steering, or joystick drilling, is a
downhole
electric-over-hydraulic powcr pack. This BJ Nowsco power pack when combined
with
a rotating tool can generate torque greater than the reactive torque of the
drilling
motor. This torquc should be greater than at least 700 foot pounds and
preferably
,
greater than 1.000 foot pounds. The downhole electric-over-hydraulic power
pack can
also be advantageously used to power other downhole tools, other than a
rotating tool
or an orienting tool, such as a circulating valve, or other valves. Also for
example, the
power pack could power an emergency release tool. The power pack could power a
fotm of orienting tool that varied the offset of an offset joint, such as bent
sub angle.
(Rams or cams, as well as bents subs, can form species of offset joints, as
that term is
used herein.)
The power pack i>: preferably powered by an electric line that runs through
coiled tubing. Running an electric line through coil instead of hydraulic
lines has
several advantages, one being space. Reversible DC motors are preferably
selected for
the electric motors. Given space constraints, preferably three DC motors would
be run
in sequence. In a preferred embodiment a hydraulic pump is placed both above
and
below three DC motors. A clutch is provided for each pump, so that when the
motors
are run in one direction one of the two hydraulic pumps generates hydraulic
pressure in
its line while the clutch slips the other pump. When the electric motors are
run in the
opposite direction. the other clutch slips and the tirst clutch engages so
that the other
hydraulic motor generates pressure in its line. The availability of two
hydraulic lines
facilitates powering double acting pistons. Check valves can be used to lock
double
acting pistons in place. High pressure relief valves can be used to
differentially run
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CA 02578726 2007-03-09
second and third systems off the same hydraulic line as the first system. For
instance,
a first level of pressure could be used to move a piston relating to a
rotating orienting
member. If the piston were moved to one of its end positions and pressurc
subsequently built up, a relief valve could open that would allow the
hydraulic fluid to
= 5 then operate a circulation valve, for instance, or a second double acting
piston system.
A third relief valve could be placed on the same hydraulic line such that
after the
second piston had been moved to its stop position, pressure further builds up
to open a
third valve and to permit the hydraulic line to adjust the degree offset of an
offset tool,
for example, by running a third piston system.
A further aspect of the invention derives from the high level of torque
generated
by the downhole electric-over-hydraulic power pack when combined with a rotary
orienting tool. An orienting tool including a rotating member may preferably
be
utilized to rotate a bent sub or any othcr spccies of offset sub. The high
pressure
utilized to generate a sufficiently high torquc on the rotating member to
rotate while
drilling has led to thc development of a "balanced pressure" rotating member.
Balancing the pressure on the rotating member avoids placing excessive force
on thrust
bearings supporting the rotating member. "Balanced pressure" is used to refer
to a
design wherein a helical surface receiving the pressure or force from the
piston in one
longitudinal direction is part of the member that also experiences a counter
balancing
force in the longitudinal direction due to the hydraulic fluid in the piston
chamber.
One way to attempt to express this "balanced pressure" design is to state that
the piston
chamber is located in the unit that contains the helical gears that mate with
the helical
gears on the piston.
A further feature of the high powered orient-while-drilling system comprises
the
use of helical gears. The piston imparting rotational movement to a rotating
member to
orient an offset joint (such as a bent sub) preferably uses helical gears
mating with
similar gears on the rotating member, in lieu of a lug or key in helical slot
system.
Helical gears transmit rotational movement to the rotating member. Helical
gears can
be viewed as a key in helical slot system, and vice versa, wherein the contact
surface
area between the key and slot has been substantially extended.
A further inventive aspect of tbe orient-while-drilling system comprises the
arrangement of the tool modules in the bottomhole assembly. The orient-while-
drilling
= system places the steering tool and instrument module, including non-
magnetic collars
if used, above the power pack and orienting system. The orienting tools are
placed
proximate to or next to the motor and bit or next to a bent sub followed by a
motor and
bit. Locating the orienting tool near the motor and bent sub has mechanical
advantages
in terms of rotating an offset joint, or bent sub, against frictional and drag
forces.
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CA 02578726 2007-03-09
In the BJ Nowsco system although preferably the steering too) is located
uphole
from the orienting tool, it is yet connected to a rotating member of the
orienting tool
such that the steering tool rotates with the rotating member. By such means
the
steering tool tzacks the rotation or orientation of iLn offset joint or bent
sub. A quick
release tool is preferably connected between a coiled tubing grapple connect
and the steering tool and instrument module assembly. An orienting tool
assembly may
include the DC motors and hydraulic pumps, a circulating valve if operated off
the
hydraulic pumps, and the orienting tool or tools. A bent housing or other
offset joint
may be located immediately below the orienting tool or in or associated with
the motor
and bent housing. A current belief in the industry is that it is necessary to
locate the
steering tool as close as possible to the bit. It is the experience of the
present inventors
that greater advantage is achieved by locating the orienting tool adjacent the
motor and
bit.
An electric line prefcrably feeds the DC motors of the power pack. The
electric
line could also power a releasc tool. Preferably lincs also exist to provide
for the real-
time communication of data from the steering tool, although other
communication
means are known and can be used. Real-time surface monitoring of downholc data
permits joystick drilling. A feedback control loop can govern the rotating and
orienting while drilling.
The orient-while-drilling system is capable of rotating in either direction to
any
degree, limited only by the piston stroke (in a preferred crnbodiment up to
400 ) while
drilling, at any time. In practice, corrections would probably be made only
when the
deviation appeared larger than the noise in the stecring data. With the orient-
while-
drilling system the operator is free to manage the weight on bit in order to
suit other
needs. The weight on bit need not be managed in order to fine tune the
orientation of
the offset joint or bent sub.
The availability of a downhole electric-over-hydraulic power pack capable of
generating high pressure makes available a hydraulic system capable of
adjusting the
degree of offset of an offset joint, or in terms of a bent sub, the bend
angle. The
hydraulic system of the power pack could also be utilized to operate a
centralizer,
including a centralizer with an adjustable diameter which could function as an
anchor.
To review uses for the bottomhole assembly incorporating the downhole
electric-over-hydraulic power pack, the hydraulic power can be used to set any
valve or
combination of valves, not just a single function circulation valve. Tbe,
hydraulic
power from the power pack can be used to hydraulically operate an offset
centralizer or
a hydraulically operated coaxial centralizer. The coaxial centralizer could be
of
hydraulically variable diameter. A hydraulically operated variable diameter
centralizer
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CA 02578726 2007-03-09
could be used to anchor the tool through the wellbore in addition to merely
centralizing. The downhole eleetric-over-hydraulic power pack can also be used
to set
compression tight mechanical packers. The bottomhole assembly, although
adapted to
be used with coil tubing, is not limited to coil tubing. It could also be
advantageously
used in many situations with jointed pipe.
An orient-while-drilling system offers a geo-steering method that need not be
tied to a predetermined path. The guidance for geo-steering may bc result
driven, may
be real-time data driven, in addition to or in variance from a predetermined
path or a
predetermined endpoint. With true geo-steering, a predetermined path in a
target
] 0 reservoir may not exist. There may be a general idea as to where to go but
the course
may be drilled using instruments to follow the reservoir strata, or
wheresoever that
appears to lead in real-time, based upon real-time data. In the build section
of a well a
gamma signal can be used to identify rock strata as the build curve develops.
The
incoming gamma information may dictate adjusting the build design. To the
extent a
predetermined path exists, it is constantly being changed and modified.
optimized and
updated.
An alternate embodiment of the bottomhole assembly could include the
placement of a check valve or a back pressure valve between the motor and the
bit.
11 is not necessary for an orienting tool to use rotation to align a bent
housing or
any other offset joint. Furthermorc, rotation need not be imparted through the
use of
helical gears to translate longitudinal movement into rotation.
In the orient-while-drilling system the axial position of the bent housing is
preferably continuously monitored. The spacial position of the bent housing
may be
periodically calculated. Continually monitoring the axial position of the bent
housing
allows the operator to correct the position of the bent housing in small
increments, as
soon as it exceeds an acceptable tolerance span.. Such system minimizes la.rge
sudden
changes of the wellbore which could lead to problems with the well later when
it is
lined or serviced. The spacial position of the bit is kept thereby more
closely on line.
Typically, when the spacial position of the bit is calculated, a new
intermediate path is
determined that merges with some original predetermined path or special target
at
= some point distant from the current location of the bit. The drilling now
continues as if
the new intermediate path were the original predetermined path.
Although the directional drilling using coil tubing bottomhole assembly is
capable of orienting when pulled off bottom, typically it is designed to
orient on
bottom in conjunction with drilling and preferably continually monitoring the
axial
position of the bent housing.
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CA 02578726 2007-03-09
Strictly speaking a bent sub is rotated relative to the earth. The instruments
in
control are set up to measure and control the bent sub's rotation relative to
the earth.
In the orient-while-drilling system the coil is held while drilling at the
surface
to control the weight on the drill bit, but not the axial rotation of the
coil. When there
is weight on bit, the coil collapses into a spiral downhole that provides a
friction lock,
preventing rotating of the upper portion of the coil. Given such friction
lock, there is
no need to hold the tubing against axial rotation at the surface during
orienting-while-
drilling maneuvers. If the bit were rotated while pulled off bottom, the
tubing might
likely have to be held against axial rotation at the surface.
In somc circumstances the orienting-while-drilling system will also calculate
bit
position with respect to the earth while drilling.
What is claimed is the invention substantially as disclosed, including its
inventive aspects singley and in combination.
EXAMPLE 1
Position of the Orienting Tool. Problem: How much torque is required to
orient the toolface of a prior art drilling assembly compared to the instant
design? =
Calculate frictional torque resisting the rotation of a DUCT BHA in open hole.
Assume 3 point bending with forces applied at the extreme ends and middle of
the
BHA. Only the lower portion of the BHA rotates.
Dimensions:
BHA: Length: overall70ft
rotating part (a) 15ft {NOWSCO}
(b) 35ft {prior art)
OD: 3.125"
ID: 2.5"
Hole: ID: 4.75"
Radius of curvature: 80m
Coefficient of friction between BHA and hole: 0.30
Axial load: (a)
(b) 30001bf
Results:
The torques required to overcome frictional drag are as follows:
(a) Instant Design BHA: 2-30 ft lb
(b) Prior Art: 20-300ft lb
Discussion of Exampie: The reason for the large spread in the predicted prior
art results arises from the much higher probability that their BHA will have
to rotate at
two contact points instead of one. If the central section of the BHA has to
rotate then
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CA 02578726 2007-03-09
it encounters a large bearing force against the hole. Since the contact points-
are highly
variable in position the required torque is similarly variable. The location
of the
orienting tool of the instant design is chosen to avoid the need to rotate the
middle
section of the BHA.
Orientina While Drillin. The instant orienting tool is designed to provide
sufficient torque allow toolface adjustments to be made while the drill bit is
working.
This requires torques in the range 300-1000 ft lb. The adjustment is
infinitely variable
in both right and left hand directions. Drilling fluid can be circulated
continuously
during orienting adjustments so that the drilling process is not interrupted.
The prior
art tool appears to be unable to produce torques of the magnitude needed for
continuously drilling. This is due to its reliance on the working pressure
difference
between the inside and outside of the tool e.g. typically 1000 psi and the
cessation of
drilling fluid flow required for resetting the tool. The toolface position is
changed in
10 degree increments.
Actuator Desi~n. The instant design is powered by a closed hydraulic system
developing typically six limes more differential pressure than the prior art
tool.
Motive powcr is electric. The prior art design is dependent on the drill motor
and bit
diffcrential pressure. The instant design makes use of helical teeth or slots
in both
designs.
Steerine Tools. The instant design is opcrable with a variety of steering tool
packages, some of which have been in service for more than ] 0 years.
Circulating Valve. The instant design contains Iwo methods for bypassing the
drill motor assembly.
= Bursting Disc: an over pressure rupture disc
= A servo conuolled 3 way valve which simultaneously opens a bypass
port and shuts off drilling fluid from the drill motor assembly.
This feature is essential to the reliability of open hole drilling with low
circulation
rates. The prior art tool does not have this function.
Safety Release Joint. A surface controlled device for separating the BHA in
two
parts while also recovering ihe steering tool assembly. This feature is not
included in
= the prior art design.
Measurement of Downhole Pressures. The instant design includes 2 pressure
measuring elements, analogue to digital signal conversion and a multiplexor
for
transmission of the pressure valves to a surface recording/display package.
The prior
art tool does not have this function.
OrientingTool. The rotary actuator used in the Nowsco directional drilling
tool
still has the highest torque capability of any downhole rotary actuator. This
is
6
CA 02578726 2007-03-09
beneficial as it allows the orienting tool (which includes the rotary
actuator) to
overcome reactive torques of large downhole motors as well as severe friction
drag
resulting from the ever tightening build radii requested by our customers.
The use.of rotary actuators is not new, indeed our actuator bears several
features
in common with sorne surface devices. What makes our tool unique is its very
high
torque output compared with its diameter. There is one design concept that
makes this
possible. That is the pressure balancing of the actuator piston. Traditional
actuators
use large thrust bearings to counteract the large axial forces, developed
hydraulically,
translated into rotary torque by spiral gears or keys. This axial thrust is so
large that it
becomes very difficult to fit in bearings capable of handling the load.
Various designs
have been employed historically to convert axial force into rotary torque. In
our case
the axial force is developed by hydraulic pressure. It has always been a
challenge to
generate large torqucs within a compact diameter, and within a compact length.
The
two design problems to be ovcrcome are first how to handle the large torque,
in our
case handled by precision helical gears, and second, how to handle large axial
force.
Our invention solves the second problem, to my knowledgc uniquely. We
construct a pressure balanccd actuator shaft. This is achieved by skillfully
designing
shaft and piston sealing diameters to balance the axial forces on the shaft
generated by
pressure versus those generated by torque on the helical gears. (A fairly
complex
equation can be pTesented showing the relationship emploxed to determine the
diameters required for pressure balance). This reduces the axial load
component
reacted by a rotary thrust bearing by a factor of about 10:1. This in turn,
allows us to
build much more compact actuators.
Pressure Balance Definition. Pressure balancing refers to the method of
minimizing any axial force imparted on the rotating actuator shaft, relative
to the non-
rotating housing. In essence, this requires that,the pressure cavity used to
hold the
actuator piston is in the same component as the spiral grove used to inducc
rotary
motion of the shaft. For example, if the piston is housed within a pressure
cavity
within the shaft, then the spiral groove used to generate torque must also be
on the
shaft, not in the housing. If the piston is housed in a pressure cavity in the
housing,
then the spiral groove must be placed in the housing, not on the rotating
shaft.
The shown embodiments show the combined use of a straight groove and a
spiral groove. It is also possible to schieve pressure balance using Iwo
spiral grooves,
and a piston housed in a cavity that is intermediate to the shaft and the
housing.
Minimizing the axial force on the rotating shaft relative to the fixed housing
allows much larger pressures and torques to be derived from the same compact
unit, as
much smaller rotating thrust bearings are required.
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CA 02578726 2007-03-09
The diagrams show a peg and groove arrangement. The preferred embodiment
is to use straight and helical gears, rather than pegs and grooves.
Circulating Valve. This invention is a sub component of the novel directional
drilling system.for coiled tubing. A circulating valve is a valve that can be
opened and
= 5 closed. When it is closed, all the flow is diverted down the tool string,
when it is open,
the flow is diverted through a port in the outside of the tool.
Circulating valves were commercially available at the time of this invention.
However, there were no circulating valves operated by hydraulic pressure. The
Nowsco circulating valve uses a downhole hydraulic pump that can drive
traditional
hydraulic devices. The use of such a hydraulic drive mechanism has not been
previously utilized for the operation of a downhole circulating valve.
The original coil tubing drilling strings all had a weakness in that they did
not
have circulating va]ves. The circulating valve is required for drilling
operations for
one or both of the following reasons:
To pcrmit circulation downhole without operating the downhole drilling
motor;
To permit circulating flow rates in excess of what can be safely pumped
thTOugh the downhole drilling motor to movc the drill cuttings up the
wellbore.
The instant invention allowed a circulating valve to be incorporated into the
drill string in a simple and efficient manner using hydraulic pressure
generated by
downhole hydraulic pumps. The use of hydraulic pressure allows for reliable
operation
as simple, proven hydraulic valving can be used to control the device.
The present inventors had the first system incorporating a circulating valve.
However, other companies have now also developed circulating valves. These
competing valves, to my knowledge, are not operated off hydraulic circuits and
will
likely prove to be less reliable, or less flexible in.operation.
Adjustable Offset Joint. The invention is a new method of achieving a
downhole adjustable bent sub for mutli-lateral operations including
directional drilling.
The method involves using a downhole pump, used io generate high hydraulie
pressures. This hydraulic pressure is then converted to a force used to either
straighten,
= or bend, an adjustable bent housing, or else adjust the offset on an offset
centralizer.
The exact mechanism of converting pressure to force, required to achieve
movement of the bent sub, can take many forms. It will require either an
angled rotary
actuator, a rotary swash plate or a linear drive moving a hinged joint, or
else an offset
centra]izer, adjustable by either linear or rotary motion of the centralizer.
8
CA 02578726 2007-03-09
The ideal embodiment will provide for a tool with hydraulic feed back, showing
whether the tool has changed position or not, and will not permit the
possibility of
adopting a high side other than that set up on surface, even if the tool
malfunctions.
Drillin .. Directional drilling has become the most common form of drilling.
Further trends have been towards horizontal wells=with smaller boles and with
tighter
build radii. There has also been a trend towards drilling with coiled tubing.
A typical horizontal well consists of two parts, first the build section,
which is a
curve drilled to take the well trajectory from basically vertical to basically
horizontal.
The second is the horizontal section itself. These two sections require
different tool
functions. In the build, the goal is to build angle quickly. The horizontal
section
requires mostly the maintenance of a straight hole, although some corrections
in both
azimuth and inclination are invariably required.
Presently, the drilling assembly has to be tripped out of hole so that it can
be
configured for one of the two drilling sections. This invention would permit
both
sections to be drilled in a single trip, adjusting the tool configuration
downhole, when
drilling switches from the build section to the horizontal section. This will
save much
time in the drilling program. Systems have been developed that attempt to
achieve this
function, but none so far are commercially and technically viable.
Several other problems associatcd with directional drilling are solved by this
invention. The tool string can be run in and out of the well in the straight
position,
reducing the risk of the tool hanging up and reducing the size of the surface
equipment
required. Also more control of the build section can be achieved as the build
rate can
be adjusted as the build is drilled, for example by drilling a portion of the
build with
the bent housing straightened.
The novelty with this invention is the use of high pressure hydraulics
downhole
to achieve the functionality. Using hydraulics allows the generation of large
forces,
required to operate the tool, and also permits the use of standard hydraulic
valving to
fulfill feed back and control options.
The instant inventors already have experience in downhole hydraulies, as our
orienter and circulating valve are hydraulically driven. Our orienter, unlike
all others,
is placed directly above the drill motor, meaning that we, unlike others, can
easily
utilize our orienter hydraulics to operate an adjustable bent sub positioned
directly
above the motor.
SUMMARY OF THE INVENTION
The bottomhole assembly, including the preferred embodiments of the above
described tools or subs, was developed initially to operate with a downhole
drilling
9
CA 02578726 2007-03-09
motor. However, in some configurations the BHA is applicable to, and can be
advantageously used for, other well operations and applications. The
invention,
therefore, is not limited to drilling applications.
The BHA was also designed particularly to be connected to and used with coiled
tubing. Coiled tubing is particularly favorable for continuous operations,
such as
orienting while drilling. However, the bottomholc assembly as designed could
be used
with tubulars, or jointed pipe, at least in some circumstances. Thus, the
invention need
not be limited to use with coiled tubing.
In operation, a BHA power pack tool of the instant invention would be
connected to a source of electricity at the surface. Preferably electric power
conveyed
by an electric line run through tubing would power a downhole electric motor
or
motors. Preferably, the electric motors are reversible, DC and structured to
comprise a
series of motors. For certain operations, such as orienting while drilling,
the power
pack should generate at least 700 foot pounds of torque in conncction with
roiating an
orienting tool. A hydraulic pump attached both above and below the electric
motor(s)
makes possible the actuation of double-acting pistons. Clutches can slip the
hydraulic
pump out of service if not being used.
When the BHA is used for drilling, the BHA preferably combines its tools such
that a steering tool is attached above a power pack which is attached above an
orienting
tool. The orienting tool is then advantageously located toward the bottom of
the BHA,
proximate to where attachment is made to a downhole drilling motor and bit and
offset
joint. Preferably, the orienting tool is located on the bottomhole assembly in
proximity
to an offset joint. The drilling motor might intervene between the orienting
tool and
the offset joint, depending upon the motor/offset joint/bit configuration
being used.
Frequentiy, the motor/joint/bit unit is leased from third parties. The
orienting tool
preferably would have two members that in operation rotate with respect to
each other.
The first member is be adapted to be connected in fixed rotational or axial
position to a
connecting sub that connects the BNA to the tubing. The second member is
adapted to
be connected in fixed rotational or axial position to a portion of a steering
tool. In
operation, thtts, this portion of the steering tool and member of the
orienting tool is
connected in fixed rotational or axial position to a rotating offset joint.
Preferably, the
BHA includes a release tool attached between a sub connecting the BHA to the
tubing
and a steering too]. The release tool could be electrically powered. ln
operation, a
release tool so situated can separate the tubing from the bulk of the BHA.
Preferably,
also the BHA includes a circulating valve. The preferred location for a
circulating
valve is above the orienting tool for drilling operations. Preferred
embodiments of a
BHA might also include an adjustable centralizer, and preferred embodiments
used for
CA 02578726 2007-03-09
drilling might include an adjustable offset joint. In operation, a downhole
adjustable
centralizer could be adjusted by using the hydraulics from a power pack. Such
an
adjustable centralizer might be structured to be adjusted to provide an anchor
for the
BHA. In operation, an adjustable offset joint could be adjusted downhole to
vary the
bend angle of the drilling, and could include the option of straight drilling,
without
tripping out of the hole. An adjustable offset joint could also adopt a
straight
orientation for running the BHA into and out of the hole. An adjustable offset
joint
would preferably be located between the orienting tool and the motor.
In operation, an important aspect of the BHA for downhole drilling includes
means for communicating wel]borc and drilling data to a surface facility. The
preferred means of communicating would be by electric line running through
tubing.
Other reliable means of communicating downhole data, however, exist. The
communicating of real time downhole data facilitates orienting while drilling.
"Real
time" data, as that term is used herein, may be communicated essentia)ly
continuously
and essentially contemporaneously with its collection. Alternately, "real
lime" data
might also be packaged and communieated in bursts, lagging a few seconds
behind the
data's time of collection. Real time data preferably includes data relating to
the axial
location of the offset joint, the spacial location of the BHA, and formation
and/or
reservoir data. Data whose communication lags collection by several minutes
would
not he regardcd as real time.
The invention includes a BHA for use with a downhole drilling motor that
includes an orienting tool having a member that defines an end of a piston
chamber
opposite the piston. This member also has a helical element mating with an
element of
the piston operable in the chamber to create a balanced pressure orienting
tool. The
orienting tool has a second member with respect to which the first member
notates and
preferably the relative rotation is bidirectional and up to at least 360 in
response to
movement of a double-acting piston. Preferably also, the rotation is not
limited to
fixed steps.
For downhole drilling motor operations, the BHA may include a circulating
valve structured to divert a portion of fluid communicated down the drill
string, such
as the drilling fluid. The fluid is to be diverted around the drilling motor
and into the
wellbore. An electrically powered hydraulic pump preferably operates such a
circulating valve.
A BHA for use with a drill string and downhole drilling motor rnight include a
downhole adjustable offset joini with the offset being adjusted in response to
translational movement of a double acting piston. The piston could tcanslate a
nonaxially aligned shaft wheiein the translation of such shaft creates an
offset joint.
1t
CA 02578726 2007-03-09
Adjusting the degree of the offset involves selecting the position of the
shaft. The
translation of the piston is best activated by an electric-over-hydraulic pump
attached
to the BHA. Alternately, the degree of offset of an adjustable offset joint
could be
adjusted by means of two members that ate pivotally attached to one another.
The
degree of offset would be a function of the pivotal relationship between the
two
elements. This pivotal reletionship, in turn, could be governed by the
movement of a
piston in a chamber.
As mentioned above, the invention may include a bottomhole assembly that has
a downholc adjustable centralizer. The centralizer could have a plurality of
adjustable
arms. Preferably, an electric-over-hydraulic actuator in fluid communication
with the
piston would connect with the arms and adjust the diameter defined by the
arms. Such
an adjustable centralizer might provide arms with the capacity to adjust
outward such
that the centralizer could forni a downhole anchor for the BHA. Preferably,
the
centralizer arms would adjust in response to the movement of a double-acting
piston.
The invention is particularly directed to a method of directional drilling
that
comprises transmitting steering information from a BHA to a surface facility
while
drilling, determining a steering correction and rotating an offset joint while
drilling.
The steering information could include a variety of information. However,
somc corrections could be based upon minimal information. Preferably, all
steering
information and downholc data would be processed by a computer facility. The
steering information should include information relating to the axial
orientation of the
BHA. In particular, this information should relate to the axial orientation of
an offset
joint. The steering information should also include information relating to
the spacial
location of the BHA. This information may relate to the spacia) location of
the bit or
to any other element along the BHA. Preferably, steering information also
includes
formation andlor reservoir data. The best steering strategy might be to follow
some
formation or the reservoir as opposed to any predetermined path, or to aim for
a spacial
target.
The instant method of directional drilling is particularly applicable to the
use of
coiled tubing as the drilling siring. With coiled tubing as the drilling
string, and with
practicing orienting while drilling, the drilling need not be stopped to
either add a joint
to the drilling string or to effect an orientation change.
The steering information should be real time at least at important times, but
may
be batched and transmitted to the surface petiodically, as opposed to
substantially
continuously, according to the best strategy for data communication with the
equipment used.
12
CA 02578726 2007-03-09
. ~ -
Given the availability of computer processing of data, especially real time
data,
as well as reliable conimunication facilities, the data could bc processed and
the
steering correction determined off-site, as in a central direetional drilling
facility,
remote from the drilling location. ln such a manner, one directional driller,
and
possibly one computer, could manager a plurality of directional drilling
operations,
even simultaneously.
Preferably, orienting while drilling includes powering a downhole electric-
over-
hydraulic motor attached to a BHA. The drilling includes operating a downhoic
drilling motor and drilling element attached to a BHA. Orienting typically
includes
]0 relatively rotating two elements of an oricnting tool. One element remains
in fixed
axial relationship to the offset joint. The other element remains in fixed
axial
relationship to the drilling string, or at least to the lower portion of the
drilling string
attached to the BHA. Drilling strings may well twist or torque between the BHA
and
the surface during drilling. Preferred orienting tools and methods of the
present
]5 invention permit rotating an offset joint in varying amounts in two
directions and
impart temporarily a torque or rotation to at least the lowcr portion of the
drill string
while performing the orienting. In preferred embodiments, orienting includes
maintaining a portion of the steering module in a fixed axial relationship
with the
offset joint.
20 The invention includes a method for orienting an offset joint of a BHA
downhole. The orienting includes supplying electricity from the surface to
power a
downhole electric-over-hydraulic motor associated with a BHA. The method
includcs
hydraulically translating a piston in a chamber in a BHA and converiing
longitudinal
motion of the piston to an adjustment of orientation of an offset joint. The
adjustment
25 of orientation of the offset joint might include either adjustment in axial
rotation of the
offset or adjustment of the degree of offset of the offset joint, or both.
The present invention includes a method of drilling using a downhole motor
attached to a BfIA that includes the ability to circulate at least a portion
of a drilling
fluid to the wellbore at the BHA while bypassing the drilling motor.
Preferably, the
30 drilling would be performed with coiled tubing and the circulating would
use a
circulating valve. The invention also includes a method for centralizing a
BHA,
comprising hydraulically actuating a piston in the BHA and varying a pivot
angle in a
centralizer link arm in accordance with translational motion of the piston.
The
invention includes a method of directional drilling comprising hydraulically
translating
35 a piston in a chamber in a BHA and varying a degree of offset of an offset
joint in
accordance with the translation of the piston. The degree of offset might be
varied by
13
CA 02578726 2007-03-09
hydraulically powering a piston in the BHA to achieve a desired pivot angle
between
two elements in the BHA.
BRIEF DESCRIPTION OF THE DRAWINGS
= 5
The invention will bc better understood and objects other than set forth
above,
will become apparent when consideration is given to the following detailed
description
thereof. Such description makes reference to the annexed drawings wherein:
Figure 1 illustrates the power pack of a prcferred embodiment in diagram form,
illustrating in particular the anangement of three electric DC motors in
series, with a
hydraulic pump placed above and below.
Figure 2A illustrates one embodiment of a coiled tubing drilling directional
BHA.
Figure 2B illustrates a drilling assembly schematic of a second embodiment
showing in particular how a BI-IA can be broken into modules.
Figure 3 offers a schematic of an orienting tool illustrating in cross section
a
rotating shaft connected to a steering tool above the orienting tool and
illustrating the
placement of thrust bearings.
Figure 4A illustrates in cross section a pressure balanced system for an
orienting tool.
Figure 4B illustrates in cross section a pressure imbalanced system in a
similar
orienting tool.
Figure 5A illustrates in cross section a circulating valve, open position.
Figure 5B illustrates in cross section the circulating valve of Figure 5A in
closed position.
Figure 5C illustrates, partially in cross section, a hydraulic circuit for a
circulating valve.
Figure 6A illustrates a hydraulically adjustable offset centralizer that could
form
an offset joint for directional drilling.
Figure 6B illustrates an adjustable bent sub embadiment of an offset joint,
partially in cross section.
Figure 6C illustrates another adjustable bent sub embodiment of an offset
joint,
partially in cross section.
Figure 7 illustrates, partially in cross section, an adjustable diameter
centralizer/anchor embodiment.
14
CA 02578726 2007-03-09
Figure 8 illustrates. methods of directional drilling where a surface facility
is
remote from a plurality of drilling locations and drilling is targeted to
spacial
coordinates or by formation data.
Figure 9. illustrates methodologies of the present invention.
'
DETAILED DESCRIPT]ON OF PREFERRED EMBODIMENTS
Figure l illustrates a preferred embodiment for a power pack of the instant
invention. Three DC electric motors 12, 14 and 16 are situated in series along
shaft 18
with hydraulic pump 20 attached io the shaft below the motors and hydraulic
pump 22
attached to the shaft above the motors.
Electric line 10 powers electric motors 12, 14 and 16. Electric line 10 runs
within bottomhole assembly (BHA) 32, indicated generally by dashed lines.
Electric
linc 10 runs from BHA 32 up to a source of elcctric power at a surface
facility.
"Surface facility" should be understood generically as generally out of the
wellbore. it
includes whatever location is convenient to situate equipment to service the
drilling.
The surface facility arguably could be subsea.
Hydraulic pump 22 has a hydraulic line 30 and a suction line 28. Nydraulic
pump 20 has a hydraulic line 24 and a suction line 26. Prefcrably both
hydraulic
pumps 20 and 22 would be provided with a clutch, as is known in the art.
Preferably
DC motors 12, 14 and 16 are reversible. When the motors run in a first
direction, a
clutch associated with one pump is slipped so that the motors operate only the
other
pump. The reverse is true when the motor is reversed. It will be appreciated
that the
arrangement of Figure 1 permits the pair of hydraulic pumps to operate a
double-acting
piston. In preferred embodiments the hydraulic pumps can be in fluid
communication
with a variety of tools, valves, and actuators
Figure 2A illustrates one embodiment of a coiled iubing directional drilling
BHA broken down into modules. The BHA is designed to run on coiled tubing. The
top module comprises a grapple connect 34 attached to a cable anchor 36 and
the top
half of a universal connect/disconnect joint 38. The second module comprises
the
bottom half 40 of a universal eonnect/disconnect joint, check valves 42,
release tool
44, steering tool including instrument modules and non-magnetic housing 46,
and the
top half 48 of a universal connect/disconnect joint. The third module
comprises the
bottom half 50 of a universal connect/disconnect joint, power pack 52 having
DC
motors and hydraulic pumps, more particularly illustrated in Figure 1,
circulating valve
54, orienting tool 56 and check valves 58. Appropriate subs will be used below
check
valves 58 to mate with the lower module of the bottomhole assembly comprising
motor
CA 02578726 2007-03-09
60, bent housing 62 and bit 64. Frequently directional drilling bottomhole
assemblies
are designed to mate with a variety of manufacturers' motors, bent housings
and bits.
Figure 2B illustrates a slightly different embodiment of a BHA for use with a
downhole drilling motor. Coiled tubing 66 is illustrated carrying electric
line cable 10.
Figure 2B illustrates coiled tubing connector 34 and cable bulkhead 68. A
quick
connect device follows having upper element 38 and lower element 40. Element
70
includes a multiplexer and digital to analog converter, useful as is known in
the art to
package and communicate data to the surface. Figure 2B also illustrates
pressure
sensors 72 followed by quick conneci units 74 and 76 to finish a first module
of a
bottomhole assembly. The second module of a bottomhole assembly includes
safety
release 78 , bursting disc 79 and steering too146 contained within a non-
magnetic tube as is known in the
art. The steering tool module is compieted with- quick connect devices 80 and
82 to
Snisb the second module of the BHA. The third module of the BHA includes power
pack 52 containing electric motors and hydraulic pumps as well as hydraulie
control
valves 53 and circulating valve 54. The power pack is followed in the assembly
with
orienting tool 56 attached to quick connector units 84 and 86.
Figure 3 illustrates the feature of an embodimeni of the present invention in
which an orienting tool contains a shaft that is designed to connect through
the
bottomhole assembly and through the power pack and to an element of the
steering
too1. The lowet end of the orienting tool is designed to connect to the motor
and offset
joint, such as bent housing or bent sub, and drilling element such as a bit.
In such a
manner the offset joint can be connected fixedly in the axial direction with
portions of
the steering tool. In such manner, the axial orientation of the offset joint
can be
monitored by the steering unit. Figure 3 illustrates orienter shaft 84
structured to
extend uphole in the bottomhole assembly. The downhole end 88 of the orienter
shaft 84
is adapted to attach, as by screwing, into a motor/bent housing, bent sub/bit
unit.
A downhole drilling motor and bit are frequently rented from third-party
providers. The unit may include an offset joint such as a bent housing for the
motor or
bent sub. Piston 90 is illustrated as translating in piston chamber 94. Piston
90 is
intended to represent a double-acting piston. Thrust bearings 92 help secure
shaft 84
in orienter housing 86.
Figure 4A illustrates a pressure balanced system for an orienting tool. In
Figure
4A shaft 84 is illustrated as rotating and rotatable within housing 86.
Hydraulic lines
96 and 98 provide for pressuring both sides of piston 90 in chamber 94.
Appropriate
seals are provided to define the pressure chambers. Piston 90 is restricted to
translational movement by the position of lug 104 in vertical slot 106. Piston
lug 100
moves in helical slot 102 of shaft 84. In preferred embodiments lug 100 and
helical
16
CA 02578726 2007-03-09
slot 102 would be helical gears, as is known in the art. As pressure flows in
hydraulic
line 96 to the left section of chamber 94, piston 90 is forced down or to the
right. In
the upper or left hand portion of chamber 94 hydraulic force 108 presses
against a
shoulder 103 of shaft 84. An equal force presses downward against piston 90
driving
lug 100 downward against helical slot 102. Ignoring friction, the downward
force
exerted by lug 100 against helical slot 102 on rotating shaft 84 essentially
cancels the
upward force 108 exerted by the pressure in the upper or left hand portion of
chamber
94 by the hydraulic fluid entering through line 96 on shoulder 103. Piston 90
moves
downward, or to the right, rotating shaft 84 by virtue of the rnovemcnt of lug
or gear
100 in slot or gear 102. Hydraulic fluid in the lower portion of chamber 94
can be
circulated out via hydraulic fluid return line 98.
Figure 4B, for contrast, shows a pressurc imbalanced system for an orienting
tool. In Figure 4B hydraulic fluid pressuring the upper or left hand side of
chamber 94
exerts downward force on piston 90 and an upward force on shoulder 110 of
nonrotating housing elemeni 86. Again, the forec of the hydraulics from line
96 forces
piston 90 down whereby lug 100 moves in helical slot 102 rotating shaft 84.
However,
in the embodiment of Figure 4B. because hydraulic chamber 90 and helical slot
102
opposite end 110 are not created in the same housing clement, there is not a
counterbalancing force against rotating shaft 84 to the left, or upward, to
counterbalance the downward force of lug 100 against the side walls of helical
slot
102. Thus, significant force will be placed upon ihrust bearings to be locatcd
at the
end of rotating shaft 84, as is known in the art. As illustrated in Figure 3,
thrust
bearings 92 could be placed in compression.
Figure 5A illustrates an embodiment of a circulating valve-open position of
the
present invention. Figure 5A illustrates drill fluid 112 passing through the
center of
the circulating valve. Within the circulating= valve piston 114 translates
within
chambcr 126. As illustrated, piston 114 is a double-acting piston receiving
hydraulic
pressure on the one hand from line 128 to the left or upper side of chamber
126 and
receiving hydraulic pressure from line 130 to the right or lower side of
chamber 126.
As illustrated in Figure SA hydraulic pressure through line 128 and into the
left side of
chamber 126 has forced piston 114 and shaft 122 down or to the right. In such
a
configuration port 116 lines up with port 1 l8 and apperture 124. Drilling
fluid 112
will follow the path of least resistance and egress from the center of the
circulating
valve, in its open position out ports 116, 118 and apperture 124 to a portion
of the
wellbore outside of the circulating valve.
In Figure 5B hydraulic fluid from line 130 has pressured piston 114 and shaft
122 to the upward or left-most position by applying pressure on piston 114 in
the right
17
CA 02578726 2007-03-09
or lower portion of chamber 126. In this close.d position port 116 does not
line up with
port 118 and apperture 124. Thus, drill fluid proceeding through the center of
the
circulating valve may not egress out apperture 124 to the wellbore outside of
the
circulating valve.
Figure 5C illustrates an embodiment of a hydraulic circuit for operating a
circulating valve. As
shown therein, hydraulic line 130 may have a supply valve 210. When open,
hydraulic pressure is received
at the left or upper side of chamber 126. Similarly, hydraulic line 128 may
have a supply valve 211. When
open, hydraulic pressure is received at the right or lower side of chamber
126. When the hydraulic
pressure received by the left or upper side of chamber 126 is too great,
hydraulic fluid exits line 130
through relief valve 212. When the hydraulic pressure received by the right or
lower side of chamber 126
is too great, hydraulic fluid exits line 128 through relief valve 213.
Further, hydraulic fluid may exit line
130 through the pilot relief valve 214 before reaching the supply valve 210.
Similarly, hydraulic fluid may
exit line 128 through the pilot relief valve 215 before reaching the supply
valve 211.
Figure 6A illustrates a hydraulically adjustqble offset joint, or offset
centralizer.
Double-acting piston 132 in chambei 134 moves offset centralizer or offset
joint 140
up and to the left, creating an offset joint. In its lower or rightmost
position, as
illustrated in figure 6A, offset centralizer 140 creates no offset joint.
Hydraulic fluid
through hydraulic lines 142 and 144 movc piston 132 in chamber 134.
Figure 6B illustrates another embodiment of an adjustable bent sub or
adjustable
offset joint. In Figure 6B housing element 154 is attached by pivot 150 to
housing
element 152. Flexible or loose-fitting sleeve 168 surrounds the pivoted joint.
Drill
fluid ) l2 tlows through the center of both element 152 and element 154.
Piston 156
moves in chamber 158. Again, a double-acting piston 156'is created by virtue
of
hydraulic line 162 and hydraulic line 160 powering piston 156 both ways within
chamber 158. Piston 156 connects to shaft 164 which has a pivoted connection
166
with element 154. As piston 156 moves downward, or to the right. element 154
will
rotate outward or toward the top of Figure 6B, creating an offset joint. The
rotation is
by virtue of pivoted connection 150.
Figure 6C illustrates a further embodiment of an adjustable offset joint. In
the
embodiment of Figure 6C element 172 is connected by pivot 176 to lower element
170.
Again, a ilexible or loose-fitting sleeve 174 fits around the pivot joint.
Drill fluid 112
flows through the center of both elements. Piston 178 moves in chamber 180.
Again,
piston 178 is a double-acting piston being powered by hydraulic fluid in lines
182 and
184. As piston 178 translates in chamber 189,4angled slot 176 moves over lug
188 of
element 170. As piston 178 moves down or to the right anglcd slot 186 forces
lug 188
to the outside of the tool. This force tends to rotate tool element 170 around
pivot 176
upward in the drawing to create an offset joint.
18
CA 02578726 2007-03-09
Figure 7 illustrates an adjustable diameter centralizer/anchor embodiment for
use with a BHA. Piston 196 moves in chamber 202 of centralizer element 204.
Drill
fluid 112 passes through the center of the centralizer. Element 204 is free in
turn to
translate in annular chamber 206 of element 208. Fluid from hydraulic line 198
moves
double-acting piston 196 downward or to the right in chamber 202. As piston
196 hits
against the downward or lower sboulder of element 202 it moves element 202
downward or to the right in annular chamber 206. Such movement to the right
moves
18a
CA 02578726 2007-03-09
out pivoted centralizer link arms 194 and 192. Preferably there would be a
plurality of
such two link mechanisms.
Figure 8 illustrates various aspects of preferred embodiments of the present
invention. First, Figure 8 illustrates two drilling locations, DL, and DLi.
Steering
information from bottomhole assemblies BHA is transmitted to the surface. Such
steering data is preferably transmitted by wireline inside of coiled tubing
used for
directional drilling. However, othcr mcans of communication of data are known.
The
data is preferably transmitted substantially contemporaneously witb its
collection.
That is, the data is preferably transmitted either continuously or batched for
transmission every few seconds. Figure 8 illustrates that at the surface data
is
transmitted from antennas A at the drilling locations via satellite S to a
remote surface
facility RSF. There directional driller 200 can make orienting decisions
relating to
either or both drilling locations. The data is preferably processed in a data
proeessor
DP located at the remote surface facility.
During important times at a drilling location, data is preferably transmitted
essentially rcal time to a remote surface facility RSF. Since drilling can
take place
over days and weeks, howevcr, there will be slow times even in directional
drilling.
During these times the data may be batched and sent only periodically to the
remote
surface facility, such as every thirty minutes or so, to minimize costs.
In preferred embodiments of the invention orienting decisions and corrections
will be made to optimize the drilling. It is envisioned that preferred
orienting
strategies include aiming and reaiming for a target spacial location,
illustrated as
location SL in drilling location DLõ location SL being indicated as having an
X,Y and
Z coordinate. Alternately, at drilling location DLõ the orienting decisions
might be
premised upon a desire to listen to formation data and seek out and follow a
reservoir.
The availability of reliable communications from remote locations makes
possible the managing of at least a part of the directional drilling decisions
by
directional drillor located at a central surface facility.
Figure 9 illustrates a further aspect of the methodology of the present
invention.
Figure 9 illustrates directional drilling using coiled tubing. Bit B is
illustrated as
rotating at the bottom of the hole. Bottomhole assembly BHA is illustrated as
having
bent sub BS. While bent sub is rotated by bottomhole assembly BHA in direction
201
while drilling, the lower portion of coiled tubing CT will be torqued or
rotated in an
opposite direction 202. When bottomhole assembly BHA ceases applying torque to
bent sub BS to rotate in direction 201 while drilling, then coiled tubing CT
should
unwind in a direction 203 opposite to direction 202 thereby further orienting
bent sub BS ia
direction 201. Because of the helixing of a drill string of coiled tubing CT
in wellbore
19
CA 02578726 2007-03-09
WB, any temporary torque applied to a lower section of coiled tubing CT is noi
anticipated to cause any rotation at the upper levels of coiled tubing CT in
wellbore
WB.
Rotating bit B is accepted by those in the art to have already placed a
certain
amount of rotation on coiled tubing CT in wellbore WB. The torque or rotation
placed
on the tubing due to drilling alone should be opposite to the direction of the
rotation of
the bit. Orienting or rotating while drilling must allow for and account for
the torque
on the coiled tubing due to the drilling of the bit as well as the temporary
additional
torque on the tubing due to rotating the rotating tool and offset joint while
drilling.
Resistance of the wellbore against rotation of thc bent sub is similar to
resistance of the
bottomhole of the well to rotation of the bit. Both can place a torque on a
drill string,
in particular on a coiled tubing drill string.
While therc are shown and described present preferred embodiments of the
invention, it is to be distinetly understood that the invention is not limited
thereto, but
may be otherwise variously embodied and practiced within the scope of the
following
claims. ACCORDINGLY,
