U.S. patent application number 15/787913 was filed with the patent office on 2018-04-26 for radial drilling in horizontal wells by coiled-tubing and radial drilling by e-line and slick-line.
The applicant listed for this patent is Robert L. Morse, James Mark Savage. Invention is credited to Robert L. Morse, James Mark Savage.
Application Number | 20180112468 15/787913 |
Document ID | / |
Family ID | 61971301 |
Filed Date | 2018-04-26 |
United States Patent
Application |
20180112468 |
Kind Code |
A1 |
Savage; James Mark ; et
al. |
April 26, 2018 |
Radial Drilling in Horizontal Wells by Coiled-Tubing and Radial
Drilling by E-Line and Slick-Line
Abstract
Methods and apparatus are disclosed to overcome problem that are
encountered when using coiled-tubing to deploy radial drilling
tools in certain wells. In addition, this disclosure provides means
and tools by which radial drilling tools can be conveyed and
powered by slickline or e-line. To advance the radial drilling
tools and/or to apply and control weight on bit (WOB), a chamber is
created and is then pressurized to generate a piston-affect.
Furthermore, tools and methods are provided to monitor the radial
drilling tools' operations and to convey this information to
surface personnel. In addition, because the e-line, slickline and
certain coiled-tubing strings lack adequate torsional stiffness,
torque arresting mechanisms are disclosed. This disclosure further
provides for a "zero-discharge drilling" system, a "drill-by-wire"
system, and enables radial drilling solutions in horizontal wells
using coiled-tubing, e-line or slickline.
Inventors: |
Savage; James Mark; (Ragley,
LA) ; Morse; Robert L.; (Lake Charles, LA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Savage; James Mark
Morse; Robert L. |
Ragley
Lake Charles |
LA
LA |
US
US |
|
|
Family ID: |
61971301 |
Appl. No.: |
15/787913 |
Filed: |
October 19, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62496481 |
Oct 20, 2016 |
|
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62603377 |
May 30, 2017 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
E21B 4/00 20130101; E21B
7/061 20130101; E21B 29/06 20130101; E21B 4/02 20130101; E21B 10/42
20130101; E21B 33/126 20130101; E21B 21/103 20130101; E21B 21/12
20130101; E21B 21/08 20130101; E21B 7/18 20130101; E21B 4/04
20130101; E21B 17/20 20130101 |
International
Class: |
E21B 7/06 20060101
E21B007/06; E21B 33/126 20060101 E21B033/126; E21B 4/04 20060101
E21B004/04; E21B 4/02 20060101 E21B004/02; E21B 21/08 20060101
E21B021/08 |
Claims
1. A coiled-tubing deployed system for radial drilling from a
horizontal well comprising: a surface based pump capable of
supplying fluid through coiled-tubing; a whipstock placed in a
wellbore on upset tubing; the coiled-tubing serving as a
control-line for a radial drilling tool-string positioned in the
upset tubing; the radial drilling tool-string comprising: a
flexible tool-string and head wherein fluid can traverse the
flexible tool-string and exit the head; the head configured to
penetrate casing and/or earthen formation; a chamber formed by: the
wellhead; the annulus in the upset tubing; and, a sealing apparatus
between the upset tubing and the radial drilling tools-string; said
chamber able to be pressurized so as to create a piston-affect
capable of driving the radial drilling tool-string and
coiled-tubing down the horizontal well and/or of applying weight on
bit.
2. The sealing apparatus of claim 1 either attached to the
control-line, the radial drilling tool-string or to the upset
tubing; and, selected as one from the following list: a labyrinth
seal; a ring or o-ring style seal; a cup-seal; or, a virtual seal
created by the close proximity of the radial drilling tool-string
to the inside of the upset tubing.
3. The sealing apparatus of claim 1 defining a cup-seal assembly
attached to the radial drilling tool-string or the control-line and
having one or more of the following characteristics: a cup which
faces toward the top of the well; a recess into which a portion of
the cup can fold or collapse as it is moved in the upset tubing;
or, a cup-lip having a radius or chamber.
4. The radial drilling tool-string of claim 1 further comprising a
torque arresting apparatus used to resist the reverse torque
generated by a positive displacement motor powered by the
coiled-tubing and used to rotate the flexible tool-string and
head.
5. The system of claim 1 further comprising a sensor apparatus that
can indicate at least one of the following radial drilling
tool-string operating parameters: the torque load on a downhole
motor; the pressure generated by a downhole pump; the weight on
bit; the pressure above the sealing apparatus; the pressure below
the sealing apparatus; or the differential pressure across the
sealing apparatus.
6. The system of claim 1 further comprising apparatus to
communicate one or more radial drilling tool-string operating
parameters to the surface via one of the following methods: an
electrical conductor line running through the coiled-tubing; a
fiber-optic line running through the coiled-tubing; or, via changes
in the back-pressure of the fluid in the coiled-tubing.
7. The radial drilling tool-string of claim 1 further comprising a
port-off apparatus, which directs a portion of the flow down the
coiled-tubing into the chamber allowing for the creation of the
piston-affect used to advance the radial drilling tool-string
and/or apply weight on bit.
8. The head on the end of the flexible tool-string in claim 1 that
is used to form the hole in the casing and/or in the earthen
formation, selected from the following list: a rotating mechanical
drilling bit; a non-rotating jetting nozzle; a cavitation or
pulsating nozzle; a rotating jetting nozzle; or, a jet-assisted
mechanical drilling head.
9. A system for radial drilling in vertical, slant or horizontal
wells deployed by e-line or slickline comprising: a whipstock
placed in a wellbore on upset tubing; the e-line or slickline
serving as a control-line for a radial drilling tool-string
positioned in the upset tubing; the radial drilling tool-string
comprising: a flexible tool-string and attached head configured to
allow fluid to traverse the flexible tool-string and exit the head;
the head configured to penetrate casing and/or earthen formation;
an inlet port for fluid to enter from the upset tubing annulus into
the radial drilling tool-string; a pump capable of providing
pressurized fluid to the radial drilling tool-string; a chamber
formed by: the wellhead; the annulus in the upset tubing; and, a
sealing apparatus between the upset tubing and the radial drilling
tools-string; said chamber able to be pressurized so as to create a
piston-affect capable of driving the radial drilling tool-string
and coiled-tubing down the horizontal well and/or of applying
weight on bit.
10. The systems of claim 9 further comprising a downhole filter
that is part of the radial drilling tool-string and which filters
fluid that moves from the upset tubing into the radial drilling
tool-string.
11. The system of claim 9 further comprising one of the following:
a surface-based pump system that moves fluid down the upset tubing,
where it enters the radial drilling tool-string through the inlet
port; a downhole pump that is powered by the e-line and is part of
the radial drilling tool-string; or, a dual-purpose downhole
assembly that is powered by the e-line and which both pumps fluid
through the flexible tool-string and comprises a motor used to
rotate the flexible tool-string.
12. The system of claim 9 further comprising a torque arresting
apparatus used in conjunction with one of the following: an
electric motor powered by the e-line and used to rotate the
flexible tool-string and/or head; or, a positive displacement motor
powered by fluid pumped down the upset tubing from the surface and
which enters the radial drilling tool-string via the inlet port,
and is used to rotate the flexible tool-string and/or head.
13. The sealing apparatus of claim 9 either attached to the upset
tubing; the control-line or the radial drilling tool-string; and,
selected as one from the following list: a labyrinth seal; a ring
or o-ring style seal; a cup-seal; or, a virtual seal created by the
close proximity of the radial drilling tool-string to the inside of
the upset tubing.
14. The sealing apparatus of claim 9 defining a cup-seal assembly
attached to the radial drilling tool-string or to the control-line
and having one or more of the following characteristics: a cup that
is oriented so as to expand outward when fluid is pumped into the
chamber; a recess into which a portion of the cup can fold or
collapse as the cup-seal assembly is moved along the upset tubing;
and/or, a cup-lip having a radius or chamber.
15. The upset tubing of claim 9 having an intake port allowing
fluid to pass from the annulus of the wellbore into the annulus of
the upset tubing.
16. The apparatus of claim 9 further comprising a one-way valve
that allows fluid to enter the upset tubing from the wellbore
annulus, but prevents fluid from moving from the upset tubing to
the wellbore annulus via this valve.
17. The system of claim 9 further comprising one or more sensor
apparatus that indicate at least one of the following radial
drilling tool-string operating parameters: the torque load on a
downhole motor; the pressure generated by a downhole pump; the
weight on bit; the pressure above the sealing apparatus; the
pressure below the sealing apparatus; or the differential pressure
across the sealing apparatus.
18. The system of claim 9 further comprising apparatus to
communicate one or more radial drilling tool-string operating
parameters to the surface via one of the following methods: an
electrical conductor line running through the e-line; or, via
changes in the pressure of the fluid in the annulus of upset
tubing.
19. The head on the apparatus of claim 9 that is used to form the
hole in the casing and/or in the earthen formation, selected as one
from the following list: a rotating mechanical drilling bit; a
non-rotating jetting nozzle; a cavitation or pulsating nozzle; a
rotating jetting nozzle; or, a jet-assisted mechanical drilling
head.
20. A method to performing radial drilling from a horizontal well
by means of coiled-tubing comprising the steps of: positioning a
whipstock in a horizontal well on upset tubing; connecting the
coiled-tubing to a radial drilling-tool-string comprised of: a
flexible tool-string having a conduit for conveying fluid to a
head; wherein, the head is attached: to the flexible tool-string;
allows for the ejection of fluid; and, is configured to form a hole
in casing and/or earthen formation; lowering the radial drilling
tool-string through the upset tubing; forming a chamber atop the
upset tubing by means of a sealing apparatus situated between: the
upset tubing and the radial drilling tool-string; or, the upset
tubing and the coiled-tubing; activating a surface-based pump in
fluid communication with and capable of powering the radial
drilling tool-string; generating a piston-affect used to advance
the radial drilling string and/or apply weight on bit by virtue of
pressurizing the chamber; and then, advancing the radial drilling
tool-string so as to form a hole in the wellbore casing and/or
earthen formation by virtue of the head.
21. The method of claim 20 further comprising the steps of
pressurizing the chamber to generate the piston-affect by:
porting-off a portion of the fluid pumped down the coiled-tubing;
or, pumping fluid directly into the chamber from the surface.
22. The method of claim 20 further comprising the steps of
supplying pressurized fluid to the radial drilling tool-string,
thereby allowing the formation of the hole in the casing and/or
earthen formation by virtue of one of the following types of head:
a non-rotating nozzle; a head defining a rotating nozzle; a
self-rotating mechanical drilling head; or, a mechanical
cutting-head that is rotated by a motor that rotates the flexible
tool-string.
23. The method of claim 20 further comprising the steps of using a
torque arresting apparatus to resist the reverse torque generated
by a rotating head used to drill the casing and/or earthen
formation.
24. The method of claim 20 further comprising an electrical cable
or fiber optic cable; or changes in the fluid pressure within the
coiled-tubing to report at least one of the following radial
drilling tool-string operating parameters: the torque on a downhole
motor; the weight on bit; the pressure above the sealing apparatus;
the pressure below the sealing apparatus; and/or the differential
pressure across the sealing apparatus.
25. A method for radial drilling into earthen formation with an
e-line unit comprising: placing a whipstock in a wellbore on upset
tubing; connecting the e-line to a radial drilling tool-string
comprising: an inlet port for fluid to enter from the upset tubing
annulus into the radial drilling tool-string; a flexible
tool-string and attached cutting-head wherein fluid can traverse
the flexible tool-string and exit the cutting-head; an electric
motor powered by the e-line and capable of rotating the flexible
tool-string and cutting-head; and, a torque-resisting apparatus to
counter-act the reverse torque generated by the action of the
cutting-head; activating the electric motor to rotate the radial
drilling tool-string; activating a pumping system capable of
supplying fluid through the flexible tool-string and out the
cutting-head; using the flexible tool-string and attached
cutting-head to drill a hole in the wellbore casing and/or earthen
formation; while engaging the torque-resisting apparatus to prevent
any reverse torque generated by the cutting-head from twisting the
e-line.
26. A method for deploying radial drilling tools from vertical,
deviated or horizontal wells by means of a slickline or e-line unit
comprising: positioning a whipstock in a wellbore on upset tubing;
connecting the slick-line or e-line to a radial drilling
tool-string comprising: a flexible tool-string capable of
delivering fluid to a head, which is configured to form a hole in
the casing and/or earthen formation; an inlet port for fluid to
enter from the wellbore into the radial drilling tool-string,
wherein the fluid can traverse through the flexible tool-string and
exit the head; positioning a sealing apparatus between the radial
drilling tool-string and the upset tubing so as to create a chamber
atop the sealing apparatus; activating a surface-based pumping
system that pumps fluid down the upset tubing whereby it encounters
the sealing apparatus and generates a piston-affect that is used to
advance the radial drilling string and/or apply weight on bit; and,
wherein at least some of the fluid enters the radial drilling
tool-string and powers the head; and, then, forming a hole in the
casing and/or earthen formation by virtue of the flexible
tool-string and head.
27. The method of claim 26 further comprising the steps of using
the fluid to power a motor that is part of the radial drilling
tool-string and which rotates the flexible tool-string and the head
so as to mechanically drill the casing and/or earthen formation
while engaging a torque-resisting apparatus that counter-act any
reverse torque generated by the head.
28. The method of claim 26 further comprising the formation of the
hole in the earthen formation by conveying pressurized fluid down
the flexible drill-string and ejecting the pressurized fluid out a
nozzle
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This filing claims priority to provisional patent
application 62/496,481 filed on Oct. 20, 2016. Certain further
improvements, disclosed in provisional patent application
62/603,377 filed on May 30, 2017, are also referenced and claim
corresponding priority.
FIELD
[0002] The present disclosure generally relates to the arts of
radial drilling into subterranean hydrocarbon and geothermal
reservoirs. In the art of radial drilling, small boreholes are
formed into a target zone from a main wellbore. Presently, this art
is practiced in vertical wells with tools deployed by means of
coiled-tubing. This disclosure expands the apparatus and method of
radial drilling to enable radial drilling by coiled-tubing in
horizontal wells. Furthermore, it discloses apparatus and method
for performing radial drilling in vertical, deviated and horizontal
wells using either e-line or slickline.
BACKGROUND
[0003] Natural resources such as oil and gas can be recovered by
drilling a well into subterranean formations. Typically, after the
well is drilled the tool-string is removed and casing is placed
downhole along with a cement slurry. Sometimes however wells are
completed without the casing running thru payzone, known as an
"open-hole completion".
[0004] In radial drilling procedures, specialized tools are swept
around an extremely tight radius, often completing the full change
of direction entirely inside the well casing. These tools are then
used to form one or more laterals or radials extending in a
generally radially-orientation outward from the wellbore. Radial
drilling is distinct from more-common coiled-tubing side-track
procedures and conventional horizontal drilling in several critical
ways. For example, in conventional coil-tubing and horizontal
drilling procedures, the drilling tools are swept around a radius
or "heel" that is typically hundreds or even thousands of feet in
size. By contrast, in radial drilling procedures the change of
direction normally occurs entirely within the whipstock, which is
situated inside the well casing. As production casing commonly
ranges from about 4-1/2 to 9''--this means the radius or "heel" of
the lateral is often completed in the matter of about 2 to 5
inches! Some radial drilling procedures produce boreholes that form
a true 90.degree. with the main wellbore, while others form a
lesser angle. Because of this small radius, any long tools (e.g. a
typical 6-9 ft long mud-motor used in radial drilling), never moves
into the radial that is being formed--it is impossible for them to
do so! Some procedures entail forming boreholes, but the tools
complete a portion of their sweep beyond the wellbore proper. For
example, they tools may take a few feet to complete their arc. This
size of the heal effectively limits the art of radial drilling;
and, stands in contrast to scales found in conventional side-track
and horizontal drilling. Radial drilling is characterized by the
fact that it generally operates at scale that is 2 to 4 orders of
magnitude smaller than conventional horizontal or side-track
drilling.
[0005] The current paradigm is for radial drilling tools to be
deployed by means of a coiled-tubing and in vertical wells. The
coiled-tubing not only serves as the control-line for the up/down
motion control, but also powers the downhole tools--e.g. a
mud-motor or jetting nozzle. While radial drilling tool-strings can
comprise various sub-components like filters, weight bars, swivels,
etc. a common feature is some form of flexible tool-string. Whether
rotating or non-rotating, the flexible tool-string is that portion
of the tool-string which transitions around the radius of the
whipstock and has a head used to form the hole in the casing and/or
the lateral in the formation. Often, but not always, radial
drilling is performed in a two-step process: with one tool-strings
used to form the hole in the well casing; and, a second used to
form the lateral borehole.
[0006] Radial drilling procedures can be performed on open-hole
completed or cased hole wells. If no opening is present in a cased
well, access to the formation to the formation must be gained by
milling out a section of the well casing or forming a hole in the
casing. Once access to the formation has been gained, tools are
then directed at the target formation by the whipstock. Sometimes,
radial drilling tools are deployed by means of jointed-tubing, but
such methods are not germane to this disclosure.
[0007] Perforations typically reach about 1 to 2 feet into the
reservoir, essentially bounding what might be called the "near
wellbore area". Conventional sidetrack drilling techniques reach
many 100 s or feet and often over 1000 s of feet, essentially to
what might be called the "extended drainage well boundary". By
contrast, radial drilling entails forming boreholes that extend to
what is perhaps best described as the "well vicinity"--e.g. from
about 10 to somewhat over 100 feet from the wellbore. Indeed, given
the large differences in size of the heel, it should not be a
surprise that the tools used in radial drilling have great
difficulty reaching beyond the distance of the well vicinity.
[0008] Described more fully in the paragraphs below, there are
several shortcomings with current radial drilling apparatus and
methods. For example, the continuous nature of coiled-tubing makes
it an ideal deployment method for radial drilling tools in vertical
wells--where lowering the tools is done with the benefit of
gravity. By itself, coiled-tubing, however, is not a good
conveyance means in horizontal wells due to its propensity to
encounter stick-slips, helically-buckle and, ultimately, encounter
helical lock-up. The genesis of these problems stems from the fact
that coiled-tubing lacks sufficient axial rigidity or "stiffness"
to be pushed into long horizontal wells. In fact, these problems
become even more pronounced as one uses progressively smaller
diameter and hence less-stiff coiled-tubing. Thus, with known
apparatus and methods it is not possible to reliably perform radial
drilling in horizontal wells via coiled-tubing.
[0009] It is desirable to deploy radial drilling tools by means of
e-line and slick-line, but suitable apparatus and methods are not
known. Specifically, deploying radial drilling tools in deviated,
slant or horizontal wells is not possible without a means to
address the e-line or slickline's lack of rigidity. In fact, the
problem is even more acute when compared to coiled-tubing, as
e-line and slicklines are typically far more flexible than
coiled-tubing. Other problems also confront e-line and slickline
radial drilling deployment. For example, a slickline unit in and of
itself has no means to power a downhole tool; and, neither a
slickline nor an e-line provide fluid to wash the cuttings from the
head. In addition, known radial drilling practices are unable to
offer a closed-loop drilling system, which relies solely upon fluid
already present in the formation. Instead, foreign fluids must be
introduced, presenting resource and logistics issues, as well as
the risk of formation incompatibility.
SUMMARY
[0010] This disclosure solves several short-coming related to known
radial drilling tools and methods. Most notably, it expands upon
the types of wellbores and deployment systems that can be used with
radial drilling tools. Specifically, this disclosure enables radial
drilling to be performed in horizontal wells by coiled-tubing. In
addition, it provides method and apparatus to enable radial
drilling by e-line or slickline systems, including in slant and
horizontal wells. Notably, this disclosure addresses the inadequate
longitudinal stiffness of these control lines, while also solving
the problem of the reverse torque created by mechanical, rotating
drilling tools. Other notable features of this disclosure include:
a zero-discharge drilling solution; the ability to utilize an
electric motor for radial drilling; the ability to power a
mud-motor in e-line and slickline deployments; and, reporting of
key radial drilling operating parameters like weight on bit (WOB),
torque and pressures via a fiber optic or conductor cable in the
coiled-tubing or via the e-line conductor cable.
[0011] In most methods of deployment, a sealing member or "seal"
between the upset tubing and the radial drilling tool-string (or
the control-line, itself) is used to form a chamber in the upset
tubing annulus above the seal. Several types of sealing mechanisms
are disclosed, including certain preferred cup-seals. The seal and
the chamber formed thereby (with the wellhead) are used in
conjunction with fluid or gas to generate a differential pressure
across the seal in order to create a piston-affect. The
piston-affect is then used to drive the radial drilling tool-string
further into the well. By providing slack in the control-line, the
tool-string can thus be propelled down slant or deviated wells or
along horizontal wells. Furthermore, this same approach can be
utilized to apply or increase WOB, such as is needed for mechanical
drilling procedures. With these apparatus and methods, one can
overcome the problem of stick-slips and helical buckling/lock-up in
horizontal wells.
[0012] In slickline and e-line deployments, the disclosure provides
for one or more inlets on the radial drilling tool-string, whereby
fluid from the wellbore can enter the tool-string. This fluid can
be used to power a downhole tool (e.g. a mud-motor or jetting
nozzle) and/or serve as the drilling fluid. This disclosure allows
mechanical radial drilling to be performed without the need for a
coiled-tubing powered mud-motor. Instead, the mud-motor can be
deployed on e-line or slick-line. Alternatively, a downhole
electric motor can be deployed via e-line. Furthermore, as e-lines
and slicklines, as well as some coiled-tubing deployments are not
capable of resisting torque, various torque arresting means are
also disclosed. These prevent twisting and damage to the
control-line, when using rotating tools.
[0013] In certain e-line deployments, one or more intake ports are
positioned between the wellbore annulus and the upset tubing. These
intake ports allow fluid from the casing annulus to enter the upset
tubing. This fluid can then enter the tool-string via an inlet
port(s), where it can to the head. After exiting the head, the
fluid returns to the wellbore and repeats the same circulation
path. Described more fully, below, this system enables a
highly-desirable zero-discharge radial drilling solution. Certain
e-line deployments utilize a one-way valve at the intake port. This
configuration allows fluid from the wellbore annulus to freely
enter the upset tubing, but prevents flow in the opposite
direction. With such a valve, if more WOB were needed or the
tool-string were having problems passing a sticking point in the
well, additional fluid could be pumped into the chamber to increase
the force of the piston-affect acting on the tool-string.
[0014] It is a further aspect of this invention to utilize an
electrical conduit, fiber optic cable, or changes in the
pressure/flow of the fluid pumped downhole to convey (to surface
personnel) key operating parameters of the radial drilling tools.
For example, one can monitor the loads via an e-line to determine
operating torque and RPM. Similarly, one can use transducers or
load/torque cells on the tools which report their values via an
electrical or fiber optic cable positioned inside a coiled-tubing
string. Additionally, one might monitor items such as flow rates or
differential pressures across the opposing sides of the seal to
better understand the forces created by the piston-affect.
[0015] Finally, it is a principal feature of this invention to
enable radial drilling in horizontal wells, something not presently
feasible with known art. That is, this disclosure provides
apparatus and methods to overcome the stick-slip and helical
buckling issues that preclude the use of e-line, slickline and
coiled-tubing units to perform radial drilling in horizontal wells.
Notably, this disclosure even allows small diameter coiled-tubing,
which is especially susceptible to such problems, to be deployed in
extended horizontal wells.
BRIEF DESCRIPTION OF DRAWINGS
[0016] The accompanying figures are incorporated into and form a
part of the specification, illustrating several aspects and
examples of the present disclosure. These figures together with
their descriptions explain the general principles of the
disclosure. The figures are only for the purpose of illustrating
preferred and alternative example and are not to be construed as
limiting the disclosure to only the illustrated and described
examples. The various advantages and features of the various
aspects of the present disclosure will be apparent from a
consideration of the figures along with this text.
[0017] FIG. 1 illustrates an e-line deployment of a radial drilling
tool-string that uses a downhole electric motor and pump to rotate
a flexible drill-string, which ejects fluid out the attached
cutting-head. As can be seen, additional fluid will need to be
placed in the well to "flood" the intake ports on the upset or
production tubing.
[0018] FIG. 2 illustrates an e-line system employing several
optional features including an anti-torque tool, cup-seals and a
one-way intake valve positioned on the upset tubing. Fluid enters
the upset tubing via the intake valve and then enters the radial
drilling tool via an inlet. The fluid is then pumped down the
flexible tool-sting and out the head--where it returns to the main
wellbore, rises again and repeats the circuit.
[0019] FIG. 3 illustrates a whipstock sitting atop an anchor with
upset tubing running only part way to the surface. This radial
drilling tool-string uses a rotating jetting nozzle to erode the
borehole. The jetting nozzle is powered by an electrical pump that
is powered by the e-line. As the drilling fluid does not need to be
brought back to the surface (to be pumped again), this is a
zero-discharge radial drilling system.
[0020] FIG. 4 illustrates a closed-loop mechanical radial drilling
system deployed by slickline. In this case, a surface-based pump
creates high pressure fluid that is pumped down the upset tubing.
The fluid enters the radial drilling tool-string and rotates a
mud-motor, which rotates the flexible drill-string. The fluid exits
the head, which is a mechanical cutting-head, to wash the cutting
away.
[0021] FIG. 5 illustrates a slickline deployed system that uses
pressurized fluid in the chamber atop a labyrinth style seal. This
system allows: the tool-string to be advanced into the well; WOB to
be applied during drilling; and, directs fluid into a mud-motor and
through the flexible drill-string to the head.
[0022] FIG. 6 illustrates a slickline deployed system wherein seals
have been positioned along the upset tubing to allow the
tool-string to be driven into the well. The fluid is then directed
into the radial drilling tool-string and out the head, which in
this case is a self-rotating jetting nozzle. The system is powered
by a pump located at the surface.
[0023] FIG. 7 illustrates a radial drilling system deployed by
coiled-tubing in a horizontal well. A ring style seal allows fluid
to be pumped down the upset tubing to create the piston-affect used
to apply WOB. Fluid pumped down the coiled-tubing is used to power
the downhole tools, which form the radial. In this case, the tools
comprise a downhole motor that rotates a flexible drill-string and
attached head defining a drill bit.
[0024] FIG. 8 illustrates a radial drilling tool-string deployed by
a coiled-tubing unit in a horizontal well. This configuration is
similar to that shown in FIG. 7, expect this time, cup-seals are
used to enable the piston-affect used to overcome stick-slips and
helical buckling of the coiled-tubing. In this case, the flexible
tool-string used to form the lateral tunnel comprises a form of
conduit (hose) and jetting nozzle.
DESCRIPTION OF EMBODIMENTS
[0025] This disclosure enables radial drilling by an expanded array
of deployment systems and in a broader array of well types. As with
existing radial drilling practices, this disclosure entails a
whipstock positioned on upset tubing. The radials of this
disclosure can be formed be formed by any number of methods. For
example, the radials may be formed by: a jetting nozzle used to
erode the rock; acid ejected from a nozzle to dissolve the rock;
lasers that vaporize the rock; heat that spalls the rock; or, a
motor that rotates a flexible tool-string to mechanically drill the
casing and/or formation. It warrants mention that this disclosure
expands the range of suitable deployment apparatus and methods, as
wells as the types of tools that can be used to form the hole in
the casing and/or formation. Finally, it is worth noting that most
current radial drilling procedures involve two tool-strings: a
first to form the hole in the casing; and, a second to form the
lateral.
[0026] The benefits of this disclosure are particularly suited to
mechanical radial drilling tools, which utilize rotation and
compressive forces to generate WOB required for drilling. Current
systems comprise a sort of flexible tool-string and attached
cutting-head, rotated by a mud-motor and controlled by
coiled-tubing. This disclosure enables such tools to also be
deployed by a motor run on a slickline or conveyed by e-line.
Moreover, by virtue of the sealing apparatus and piston-affect
disclosed herein, these e-line and slickline systems can be
deployed in slant, deviated and horizontal wells!
[0027] To expand the types of wellbores and control-lines suitable
for deploying radial drilling tools, pressurized fluid is created
above a seal (or seals) position between the upset tubing and the
radial drilling tool-string. These seals are used to create a
pressurize-able chamber bounded by the wellhead at top, the upset
tubing on the sides and the seal(s) at bottom. By then pressurizing
this chamber, a piston-affect is created which can be used to
advance the radial drilling tool-string down the wellbore and/or
apply greater WOB. To insure the desired piston-affect is created,
the pressure below the seal(s) must be less than that above the
seal(s). This can be done by assuring the fluid below the seal
freely drains (from the upset tubing) to the annulus of the
wellbore and that the fluid in the wellbore annulus is vented (e.g.
returns to an open-tank at the surface). Notably, this same sealing
apparatus can also be used for the further purpose of directing
fluid from the upset tubing into the tool-string (via the inlet)
used in certain e-line and slickline systems.
[0028] Again, by pumping--or, more specifically by
pressurizing--the fluid in the chamber, one can create a
piston-affect that drives the tool-string further into the well.
Moreover, because one can know beforehand the net surface area over
which the pressurized fluid acts and can determine the differential
pressure (acting across the seal), one can determine the net force
acting on the tool-string. As described more fully below, one can
determine the differential pressure by monitoring downhole pressure
transducers (on the opposite sides of the seal); or, one can infer
the differential pressures by monitoring the pressure in the casing
annulus and upset tubing annulus at the surface. For example, if
the effective piston area were 1.5 square inches and the
differential pressure was 1,000 psi, then the force of the
piston-affect acting on the tool-string would be 1,500 lbs. The
operator would then slacken (or advance) the control-line, allowing
this piston-affect to pull the tool-string further into the well.
Furthermore, by now monitoring (and changing) the tension in the
control line, the operator could now control the amount of WOB
applied. For example, if the control-line had a net tension of
1,000 lbs (after factoring in its weight and any buoyancy offset)
than the applied WOB would be 500 lbs (i.e. 1,500 lbs-1,000 lbs).
Similarly, in instances where fluid returns to the surface via the
annular area in the wellbore, the operator can increase or decrease
the back-pressure (e.g. choke on the return flow line), thereby
increasing or decreasing the differential pressure across the seal
and hence the net force of the piston-affect. A pump (or, in the
case of gas, a compressor) at the surface can be used to generate
the pressure in the chamber for this piston-affect.
[0029] With the apparatus and method described above, one can now
advance and apply WOB by control-lines and in wells not previously
feasible to radial drilling. We now turn to a discussion of
features of this disclosure, beginning with methods and apparatus
to power the tools.
[0030] Certain e-line and slickline embodiments have one or more
inlet ports that allow fluid from the upset tubing to enter the
tool-string. Optionally, this inlet defines a filter that prevents
contaminants from entering the tool-string. Certain e-line and
slickline deployments entail fluid pumped (from the surface) down
the upset tubing, where it enters the tool-string via the inlet
port(s). The fluid entering these ports can be used for several
purposes. For example, it can be used to rotate a mud-motor or to
power a jetting nozzle; or, it can be used as drilling fluid to
wash the cuttings from the lateral. In instances, this fluid may be
over pre-pressurized (compared to the ambient downhole pressure) by
virtue of surface pumping equipment or by a downhole pump powered
by the e-line. In some embodiments, the fluid entering the
tool-string via the inlet port(s) first enters the upset tubing
from the annulus of the wellbore via the intake port(s), described
below.
[0031] In certain preferred e-line deployments, an intake port is
positioned along the upset tubing. This intake port allows fluid to
move from the wellbore annulus into the upset tubing. In operation,
the intake port is situated above the inlet port of the radial
drilling tool-string, thereby assuring the inlet port remains
submerged in fluid. Optionally, the intake port may incorporate a
filter to prevent contaminants from entering the upset tubing.
Optionally, the intake port may comprise a one-way valve, the
purpose of which is to prevent the reverse flow of fluid into the
casing annulus--i.e. the one-way valve prevents the fluid that is
pumped into the upset tubing annulus from immediately equalizing
with the fluid in the wellbore annulus (and thereby negating the
piston-affect).
[0032] In certain by e-line deployments, the disclosure defines a
zero-discharge drilling system. In these embodiments, the e-line
powers an electric pump used to pressurize the fluid that exits the
flexible tools-string. In zero-discharge embodiments, the
circulation path of the fluid: travels from the wellbore into the
upset tubing via an intake port; enters the tool-string via an
inlet port; and is then pumped down the flexible tool-string and
out the head (e.g. jetting nozzle). This same fluid then returns to
the wellbore (washing out the cuttings); rises in the casing
annulus until it re-enters the upset tubing via the intake port.
The cuttings (which are relatively small in volume), exiting the
lateral, can simply fall to the bottom of the wellbore. This cycle
can be repeated, forming a "zero-discharge drilling" drilling
system where neither the cuttings nor the drilling fluid are
returned to the surface. Moreover, this system can utilize fluid
already in the wellbore, potentially eliminating any water
procurement and treatment issues.
[0033] Having explained the creation and control of the
piston-affect in e-line applications, we now turn to a discussion
of slickline deployments. As described above, slickline deployments
also utilize the seal(s) in the upset tubing. Unlike e-line
deployments, however, slickline deployments lack an immediate means
to power a downhole tool. With slickline only the longitudinal
position of the tool-string can be controlled--and this only by
virtue of gravity pulling the tool-string downward. To power the
downhole radial drilling tools in slickline deployments, fluid is
again directed into the tool-string via an inlet port(s). However,
instead of an electric motor, a positive displacement motor (e.g.
mud-motor or vane motor) is used. Fluid is thus pumped from the
surface down the upset tubing, where it enters the tool-string via
an inlet. The fluid then runs through the motor (producing the
necessary rotation) and travels down the flexible drill-string
where it exits the drilling-head. The fluid then returns to the
surface, where it is again pumped down the upset tubing. In yet
other slickline deployed embodiments, the flexible drill-string
comprises a jetting hose and jetting nozzle. In these embodiments,
the pressurized fluid pumped from the surface--and directed into
the tool-string by the seals and inlet--is then used by the jetting
nozzle to erode the formation. In this fashion, whether using
mechanical or jetting tools, one is using a "drill by wire" form of
radial drilling.
[0034] A principal feature of this disclosure is to allow radial
drilling deployed by coiled-tubing in horizontal wells. In these
embodiments, the coil itself serves as the pressurized fluid supply
line used to power the downhole tools. As with certain e-line and
slickline deployments, optional sealing members or seals are placed
between the tool-string and the upset tubing. The requisite
piston-affect is again created by pressurizing the chamber atop the
seal(s); and is again used to propel the tool-string (and
coiled-tubing) along the horizontal well and/or to increases the
WOB at the tool-string head.
[0035] In most embodiments, to generate the required piston affect,
surface pumping equipment can be used to pressurize the chamber.
However, in certain embodiments, the pressure is created by
porting-off a portion of the fluid pumped down the coiled-tubing.
In these embodiments, the ported-off fluid enters and pressurizes
the chamber to create the desired piston affect. To control the
pressurization of the chamber and hence the magnitude of the piston
affect, a spring-loaded check valve or other pressure drop device
could be utilized. For example, with the annulus of the well vented
and with both the annulus of the wellbore and the annulus of the
upset tubing full of fluid, hydrostatic equilibrium would be
attained. By now pumping (i.e. pressurizing) fluid into the
chamber, one would create an over-pressurization situation and
hence the desired piston-affect. Moreover, one could limit the
force of this piston affect by limiting the over-pressurization in
the chamber. For example, if the pressure inside the coiled-tubing
were 1000 psi over the hydrostatic equilibrium, but a 500 psi check
valve were installed in the port-off apparatus, than a maximum of
500 psi of differential could be applied to the chamber. Knowing
the area over which this pressure acts, one could know the drive
force of the piston affect. As before, by now slackening the
coiled-tubing one can advance the tool-string and/or apply WOB.
[0036] In various embodiments, the seals may be affixed to or made
part of the radial drilling tool-string. In addition, the seals may
be affixed to the control-line rather than the radial drilling
tool-string, proper. In these embodiments, the seals move with the
radial drilling tool-string. In other embodiments, the seals may be
affixed to the upset tubing. The seals in these embodiments are
thus essentially fixed . . . with the tool-string being moving
through them. In certain embodiments, multiple seals are spaced
longitudinally along the tool-string or along the upset tubing. By
emplacing multiple members, a robust seal can be assured regardless
of downhole conditions and whether a particular seal fails (e.g.
becomes ripped or fails to seal such as when passes-over a tubing
collar). Whether "moving" or "fixed" and whether single or many,
the seals help create the chamber that allows for the desired
piston-affect.
[0037] Having discussed the reason and placement of the seals, we
now turn to a discussion on the types of seals. This disclosure
envisions two general seal types: positive engagement seals, where
no or virtually no leakage occurs; and, virtual or proximity seals
where some leakage is allowed. Within the first category, examples
include ring seals, o-ring seals and style cup-seals. Within the
second category are labyrinth seals and "virtual seals" formed by
the close proximity of the radial drilling tool-string and the
upset tubing.
[0038] The seals or sealing members are defined by a variety of
types, shapes and materials. In certain embodiments not requiring
high drive forces from the piston-affect, one can use a "leaky"
labyrinth seal or similar "close-fit" between the outside diameter
of the tool-string and the inside of the upset tubing. Moreover,
even in these applications, one can increase the piston affect by
increasing the pump rates into the chamber. Certain preferred
embodiments entail an o-ring or ring-style seal. Other preferred
embodiments, use a cup-seal that easily flexes to pass
obstructions, yet provides robust sealing on account of the
expanding cups. As with the labyrinth and close-fit style seals, in
the event of leakage, additional fluid could be pumped into the
chamber to maintain or increase the piston affect.
[0039] Certain preferred embodiments of this disclosure enable
critical downhole operating parameters to be reported to surface
personnel. The means of conveying this information to the surface
may vary depending upon whether the control-line being used is
e-line, slickline or coiled-tubing. Before discussing how this
information is communicated, let us first talk about what
information is gathered from downhole and why?
[0040] In certain embodiments, pressure sensors are placed downhole
in the tool-string. For example, pressure sensors can be positioned
above and below the seals, so as to measure the pressure acting
across the seal--and hence the magnitude of the piston-affect. In
certain embodiments, a torque cell is positioned in the radial
drilling tool-string to measure the torque loads of a rotating
tool-string. This information can be useful to surface personnel,
who can adjust the electrical power supply or pump rates to better
control the downhole tool (e.g. motor). In embodiments, a load cell
or pressure sensor is used to measure and report the WOB, allowing
surface personnel to modify drilling parameters for a more
favorable rate of penetration (ROP). Indeed, by directly measuring
the WOB from this downhole sensor, operating personnel can
eliminate inaccuracies when deriving this value from calculations
on the piston-affect and counter-acting line tension.
[0041] Having discussed various downhole sensors, we now turn to a
discussion of how this information is conveyed to the surface. In
e-line unit deployments, the conductor cable itself is used to
convey the information to surface personnel. In slickline
deployments, one or more ports on the tool-string can be
alternately opened or closed thereby introducing identifiable
pressure changes in the fluid column in the upset tubing annulus
above the radial drilling tool-string. These pressure changes can
be read by personnel using surface-based pressure transducers. In
the instance of coiled-tubing, the conveyance mechanism need not be
the fluid in the annulus of the upset tubing, but instead can be
the fluid in the coiled-tubing itself. Indeed, this is a preferred
pathway as personnel typically already monitor this pressure. In
yet other embodiments, the coiled-tubing contains a concentric
conductor cable or a fiber optic cable to convey this information.
Indeed, electrical and fiber optic conductor are desirable to the
extent that the readings can be more accurate and multiple sensors
can be time coded or otherwise multiplexed into a single cable.
[0042] By virtue of the systems described above and perhaps more
evident from the illustrations below, with this disclosure one can
deploy and power radial drilling tool-strings via e-line, slickline
or coiled-tubing unit; and, in an expanded range of well
types--including even horizontal wells.
DETAILED DESCRIPTION OF DRAWINGS
[0043] FIG. 1 illustrates an e-line unit (2) near a wellbore (22)
wherein a whipstock (60) has been positioned on the end of upset
tubing (40) and is facing a target zone (21). An upper portion of
the upset tubing (40) has intake ports (46), allowing fluid to
enter from the casing annulus (26). At present, the fluid level
(28) in the wellbore (22) is too low to allow fluid to enter the
upset tubing (40) via the intake ports (46). A fluid tank (12) and
surface pump (10) will fill the wellbore (22) with fluid for the
formation drilling procedure. The whipstock (60) is used to direct
the radial drilling tool-string (70) toward the casing (24). This
radial drilling tool-string (70) has an electric motor (87) and
flexible drill-string (80) with attached cutting-head (82) used to
drill through the casing (24). The radial drilling tool-string (70)
has been equipped with torque arresting ears (102) that engage
mating slots (45) along the upset tubing (40). This has been done
to prevent torque from being conveyed up the e-line cable (3).
There is no inlet port on the radial drilling tool-string (70) as
the casing milling procedure does not require fluid to exit the
cutting-head (82).
[0044] FIG. 2 illustrates another e-line (2) deployment. A return
line (14) connects the casing annulus (26) to a fluid tank (12).
The fluid level (28) is near the top of the wellbore (22), allowing
fluid to enter the upset tubing annulus (42) via intake ports (46).
In this case, the intake ports (46) have been equipped with a
one-way valve (48) that prevent any fluid pumped down the upset
tubing annulus (42) from directly passing into the casing annulus
(26). A series of cup-seals (110), positioned on the radial
drilling tool-string (70), prevent fluid from draining down the
upset tubing annulus (42), past the radial drilling tool-string
(70). The radial drilling tool-string (70) comprises an inlet port
(108), filter (106), torque arresting ears (102) that engage mating
slots (45) along the upset tubing (40), and electric motor (87)
that rotate the flexible tool-string (80) and attached cutting-head
(82). A downhole pump (88) pumps fluid down the flexible
tool-string (80) and cutting-head (82). A relief port (47) allows
fluid below the cup seals (110) to equalize with the fluid in the
casing annulus (26). In this configuration, the surface pump (10)
can be used to fill and/or pressurize the upset tubing annulus
(42), if the fluid level (28) in the wellbore (22) drops below the
intake port (46) or in the event that additional WOB needs to be
applied.
[0045] To create additional WOB, the surface pump (10) is engaged
so as pressurize the fluid in the upset tubing annulus (42) above
the cup-seals (110), creating a differential pressure across the
cup-seals (110). This differential pressure creates a piston-affect
that tends to push the radial drilling tool-string (70) downward.
By allowing slack in the e-line cable (3), the radial drilling
tool-string (70) moves downward and/or WOB can be applied. The
cutting-head (82) is forming a lateral borehole (76) in the target
zone (21)--i.e. the earthen formation. As shown by the set of
curved arrows, this is a zero-discharge radial drilling system
whereby the fluid pumped out the cutting-head (82) returns to the
casing annulus (26), rises to the intake ports (46), enters the
upset tubing annulus (42), enters the inlet port (108) of the
radial drilling tool-string (70) and then re-pressurized by the
downhole pump (88), where it flow through the flexible tool-string
(80) and out the cutting-head (82).
[0046] FIG. 3 illustrates a whipstock (60) resting atop an anchor
(68) with upset tubing (40) running only part way up the wellbore
(22). The fluid level (28) in the wellbore (22) allows the fluid to
enter the top of the upset tubing (44). Weight bars (78) have been
installed above the radial drilling tool-string (70) to assure
adequate WOB at the cutting-head (82) as it drills into the target
zone (21). In this case, the flexible tool-string (80) has been
equipped with a cutting-head (82) that works by jet drilling (high
pressure fluid). As such, no torque arresting apparatus is
required. This radial drilling tool-string (70) has a downhole pump
(88) powered by the e-line unit (2). The downhole pump (88)
pressurizes the fluid, which then travels through the flexible
tool-string (80) and out the cutting-head (82), which in this case
is a jetting nozzle. The fluid exiting the cutting-head (82)
returns to the casing annulus (26), where it then enters the top of
the upset tubing (44) and re-enters the radial drilling-tool-string
(70) via the inlet port (108). The fluid flow path is shown by the
set of curved arrows.
[0047] FIG. 4 illustrates a slick-line unit (4) being operated in
conjunction with a surface pump (10) and a radial drilling
tool-string (70) comprising a mud-motor (86). The activation of the
surface pump (10) pressurizes the fluid (29) in the chamber (43)
atop the radial drilling tool-string (70) by virtue of labyrinth
seals (111), which restrict (but do not completely eliminate) the
flow past the labyrinth seals (111). This allows for a
piston-affect with the radial drilling tool-string (70), whereby
WOB can be applied to the cutting-head (82) via the flexible
tool-string (80). Inlet ports (108) direct the pressurized fluid
(29) into the radial drilling tool-string (70) and through a filter
(106). The fluid then powers a mud-motor (86) used to rotate
flexible drill-string (80) and attached cutting-head (82) which are
will now be used to drill a hole in the casing (24) and proceed to
form the borehole in the target zone (21). Torque arresting ears
(102) on the radial drilling tool-string (70) engage mating slots
(45) on the upset tubing (40) to resist the torque induced by the
cutting-head (82). Unlike the flow constriction created by the
labyrinth seals (111), the torque arresting ears (102) do not
meaningfully prevent flow down the upset tubing annulus (42). The
space (63) between the flexible toolstring (80) and J-path (62) of
the whipstock (60) allows leakage of fluid to the casing annulus
(26) as shown by arrow. The fluid exiting the cutting-head (82), as
shown by the arrow, returns to the fluid tank (12) via the casing
annulus (26) and is again pressurized by pump (10) and pumped down
the upset tubing annulus (42). The fluid flow-paths are manifestly
evident by the curved arrows.
[0048] FIG. 5 illustrates a slickline unit (4) used with a surface
pump (10), fluid tank (12) and return line (14) used to deploy and
power a radial drilling tool-string (70). In this case, the outside
diameter of a mud-motor (86) creates a virtual seal (113) with the
inside diameter of the upset tubing (40). This virtual seal (113)
induces most of the pressurized fluid (29) atop the mud-motor (86)
to enter the inlet port (108) of the radial drilling tool-string
(70). The fluid then passes through a filter (106) before rotating
a mud-motor (86). The mud-motor (86) rotates the flexible
tool-string (80) and attached cutting-head (82) to form a borehole
(76). Fluid (as shown by arrow) exiting the cutting-head (82)
returns to the fluid tank (12) via the casing annulus (26)). The
pump (10) again pumps the fluid (shown by curved arrow) down the
upset tubing (40) and into the inlet port (108), whereby the
circuit is repeated.
[0049] FIG. 6 illustrates a slick-line unit (4) performing a radial
drilling procedure. In this case, fixed position seals (112) have
been set along the upset tubing (40). Fluid from a surface pump
(10) travels down the upset tubing (40) where it enters an inlet
port (108) and passes through a filter (106) before traversing thru
the flexible tool-string (80) and exiting the cutting-head (82),
which in this case, is a rotating jetting nozzle. Fluid from the
surface pump (10) moves down the upset tubing annulus (42) and
encounters the fixed-position seals (112) bounding the chamber
(43). This causes the pressure in the chamber (43) to build to 250
psi. As the pressure below the seals (112) is only 100 psi, a
piston-affect is created, which allows the radial drilling
tool-string (70) to be advanced down the upset tubing (40) and out
the borehole (76) as slack is allowed in the slickline (4). The
fluid exiting the cutting-head (82) returns to the fluid tank (12)
via the casing annulus (26) and is re-pressurized by the surface
pump (10) to again repeat the described circulation path.
[0050] FIG. 7 illustrates a coiled-tubing unit (6) deployed system
with an injector head (16) positioned above a wellbore (22) having
a horizontal section (25). A whipstock (60) is positioned on a
scrapper (69) and upset tubing (40) running to the surface. A fluid
tank (12) and pump (11) supply fluid to the coiled-tubing (8). A
port-off apparatus (75) diverts a portion of this flow into the
chamber (43) created by a ring seal (109) that has been affixed to
a radial drilling tool-string (70) and the sealed wellhead (27),
This configuration allows for the creation of the piston-affect,
which propels the coiled-tubing (8) into the horizontal section
(25) and applies WOB at the cutting-head (82) via the flexible
tool-string (80). A mud-motor (86) powered by the coiled-tubing (8)
rotates the flexible drill-string (80), which has transition
through the whipstock (60). In this case, the cutting-head (82)
mechanically drills the borehole (76) into the target zone (21).
The fluid (as shown by arrow) exiting the cutting-head (82) returns
to the fluid tank (12), via the casing annulus (26). As this
particular coiled-tubing (8) is of a small diameter and cannot
resist the torque generated by the action of the cutting-head (82),
torque arresting ears (102) engage mating slots (45) on the upset
tubing (40) to prevent twisting of the coiled-tubing (8).
[0051] FIG. 8 illustrates a similar embodiment to that of FIG. 7
except that the whipstock (60) is set on an anchor (68). In
addition, cup-seals (110) are used so that the fluid (shown by
curved arrows) pumped down the upset tubing annulus (42) drive the
radial drilling tool-string (70) down the horizontal section (25)
of the wellbore (22) as slack is allowed in the coiled-tubing line
(8). In this instance, the flexible drill-string (80) does not
rotate as the cutting-head (82) is a jetting nozzle. As shown by
arrows, the fluid exiting the cutting-head (82) returns to the
fluid tank (12) via the casing annulus (26).
[0052] Having reviewed the figures, we now continue our discussion
of various preferred embodiments and the methods for deploying the
radial drilling tools. In certain preferred embodiments, the
invention comprises a radial drilling tool-string deployed by means
of a e-line unit. These embodiments entail a whipstock positioned
in the wellbore on upset tubing, with the e-line serving as the
control-line. The tool-string comprises a flexible tool-string and
head, which are configured to penetrate casing and/or formation.
The flexible tool-string and head are run through the upset tubing
and whipstock. Optionally, the radial drilling tool-string may
comprise a form of drilling tool that penetrates the casing, but
does not require fluid to traverse the flexible tool-string. In
other embodiments, the flexible tool-string and head may be
configured to allow for the passage of fluid out the head. In
e-line embodiments where fluid is utilized one or more inlets are
positioned along the tool-string allowing for the entry of fluid.
Optionally, the tool-string comprises a downhole motor that rotates
the flexible tool-string and which defines a cutting bit that
mechanically drills the casing and/or formation. This motor may
define an electric motor (powered by the e-line) or it may comprise
a positive displacement motor (powered by fluid). In instances
where the flexible tool-string is rotated by a positive
displacement motor, the fluid that powers the motor comes from the
annulus of the upset tubing via the inlet(s) on the tool-string. In
e-line embodiments where fluid is used a pump pressurizes the
fluid. This pump may be a surface-based pump used to pump the fluid
down the annulus of the production tubing; or, it may be a downhole
pump powered by the e-line. In e-line embodiments, where the tools
used to form the hole in the casing and/or formation are rotating
tools, a torque arresting mechanism may be used. This apparatus
prevents the reverse torque from being induced into the e-line. One
such version of this torque resisting mechanism is defined by ears
on the tool-string and extended mating slots on the upset tubing.
Another embodiment defines a camming mechanism in the tool-string,
which engages the upset tubing and prevents the further rotation of
the radial drilling tool-string (and attached e-line). Either of
these embodiments can allow for the arresting of torque during the
extended drilling of the lateral borehole. It should be noted,
however, that not all e-line deployed systems require the arresting
of torque. For example, certain embodiments employ a jetting nozzle
to erode the formation, and generate no appreciable torque needing
to be resisted.
[0053] In certain preferred embodiments, the invention comprises a
radial drilling tool-string deployed by means of a slick-line. Such
systems entail a whipstock positioned in a wellbore on upset
tubing, with the slickline serving as the control-line for the
tool-string. The tool-string comprises a flexible tool-string and
head, which are configured to penetrate casing and/or formation.
The flexible tool-string and head are run through the upset tubing
and whipstock. The flexible tool-string and head may be configured
to allow for the passage of fluid, such as by a hose positioned in
the flexible tool-string and one or more passageways in the head,
itself. Slickline embodiments utilize one or more inlets,
positioned along the tool-string, thereby allowing fluid to enter
and power the tool-string. Optionally, the tool-string comprises a
downhole motor that is used to rotate the flexible tool-string and
which defines a cutting bit that mechanically drills the casing
and/or formation. In these embodiments, a positive displacement
motor (e.g. vane motor or mud-motor) is used. The motor is powered
by the fluid pumped down the upset tubing annulus and which enters
the radial drilling tool-string via the inlet(s) on the
tool-string. The pump that supplies this fluid is surface-based. In
slickline embodiments, where the tools used to form the hole in the
casing and/or formation are rotating tools, a reverse torque may be
induced into the torsionally-weak slickline. To prevent this
reverse torque from twisting-up and damaging the slickline, a
torque-resisting mechanism is used. One such version of this torque
resisting mechanism is defined by ears on the radial drilling
tool-string and extended mating slots on upset tubing. Another
embodiment defines a mechanism that locks the tool-string to the
upset-tubing (which is able to resist the torque) by virtue of a
camming device. It should be noted, however, that not all slickline
deployed systems require the arresting of torque. For example, if
one deploys a jetting nozzle to erode the formation, no problematic
torque is created by the nozzle and hence the torque arresting
feature is not required.
[0054] In certain preferred embodiments, the invention comprises a
radial drilling system deployed by means of coiled-tubing in a
horizontal well. The coiled-tubing may be of a large diameter (e.g.
2''+), which generally has high axial and torsional stiffness; or,
it may be small diameter tubing (e.g. 5/8'') which has limited
axial stiffness and low resistance to torque (i.e. twisting). These
systems entail a whipstock positioned in a wellbore on upset
tubing, with the coiled-tubing serving both as the retrieval line
for the radial drilling tool-string, but also the power supply line
for the tool-string. The radial drilling tool-string comprises a
flexible tool-string and head, which are configured to penetrate
casing and/or formation. The flexible tool-string and head are run
through the upset tubing and whipstock. In some embodiments, the
flexible tool-string and head are configured to allow for the
passage of fluid, such as by a hose positioned in the flexible
tool-string and one or more passageways in the head, itself. In
other embodiments, the flexible tool-string does not pass fluid to
the head, e.g. such as if only cutting the wellbore casing.
Optionally, the tool-string comprises a downhole motor that rotates
the flexible tool-string and attached cutting-head. The motor is a
positive displacement motor (e.g. vane motor or mud-motor) and is
powered by the fluid pumped down the coiled-tubing from a
surface-based pump. In coiled-tubing applications, where the tools
used to form the hole in the casing and/or formation are rotating
tools, a torque arresting mechanism, like that described elsewhere
herein, may be used to resist the reverse torque. Such a device may
not be required in all instances, however. For example, when
deploying such tool by large diameter coiled-tubing (e.g. 1.5''
diameter), the low torque values generated by the rotating tools
(typically below about 150 ft-lbs) can be resisted by the tubing
itself. On smaller diameter coiled-tubing (e.g. 3/4''), however,
such torque values could twist and damage the coiled-tubing--and
hence, the torque resisting apparatus would be used. It should be
noted that not all `small diameter` coiled-tubing applications
require the torque arresting apparatus. For example, if one were
deploying a jetting nozzle in a horizontal well on the end of a
small diameter coiled-tubing unit, no appreciable torque would be
created and the torque arresting feature would not be required.
[0055] Having discussed the general deployment control-lines and
how these tools are deployed, we now continue our discussion of
optional embodiments and methodologies.
[0056] In certain e-line and slickline embodiments, the system
comprises a downhole motor in the tool-string. This motor is used
to rotate the flexible tool-string and attached head. In e-line
embodiments, the downhole motor may be either an electric motor,
powered by the e-line; or, it may be a fluid-powered motor, such as
a mud-motor. When the motor is fluid-powered, the fluid is pumped
down the upset tubing from the surface and enters the tool-string
via the inlet(s). The pressurized fluid then runs through the
motor, generating rotation, which is transferred to the attached
flexible tool-string and head. In slickline embodiments where the
means to cut the casing and/or formations is via a rotating tool,
then the downhole motor is a fluid motor is powered by a surface
pump. Similar to certain e-line embodiments, in these slickline
embodiments, the fluid is sourced from a surface-based pump,
travels down the upset tubing and enters the tool-string via an
inlet(s).
[0057] In e-line embodiments employing a downhole motor, the motor
may comprise a dual-purpose assembly that also serves as pump. In
these embodiments, the dual-purpose assembly would serve to both
pump fluid to the head and act as a motor that rotates the flexible
tool-string. Such a system enables mechanical radial drilling of
boreholes by e-line.
[0058] Optionally, e-line embodiments, may have one or more entry
points or intake ports along the upset tubing. The purpose of the
intake port(s) is to allow fluid to pass from the annulus of the
wellbore into the upset tubing, where it can then enter the
tool-string via the inlet(s). The purpose of these intake ports is
to allow for a closed loop drilling system whereby fluid exiting
the head returns to the wellbore, rises in the wellbore, enters
upset tubing form the intake port and then enters the tool-string,
where the fluid can then be pumped down the flexible tool-string
and out the head.
[0059] Optionally, the e-line, slickline or coiled-tubing
embodiments may further comprise a seal between the upset tubing
and the radial drilling tool-string or between the upset tubing and
the respective control line. The purpose of this sealing apparatus
is to allow for the creation of a piston-affect by virtue of
differential pressure across the seal. By this method of applying
higher pressure above the seal (than below), the piston-affect can
be created to advance the tool-string further into the well or to
apply WOB. In some embodiments, the sealing apparatus is formed by
a positive seal, which negates flow from above the seal to below
the seal; while in other embodiments the seal is a virtual seal
created by the close-proximity of the tool-string and the upset
tubing. Suitable seal for this purpose may be selected from the
following list: a labyrinth seal; a ring or o-ring style seal; a
cup seal; or, a virtual seal, created by the close proximity of the
tool-string to the upset tubing.
[0060] In certain embodiments, the seals used to generate the
piston-affect are cup-seals, i.e. seals that produce a mild
interference fit with the inside diameter of the upset tubing and
readily flare outward to produce an even more robust seal with
increasing differential pressure. In embodiments, the cup-seal are
integrated into the tool-string and comprise an assembly with two
parts: a main body and the cup-seals themselves. In certain
embodiments, the main body has a recess that is narrower about its
center than its ends. This recess serves as a space into which part
of the sealing element can move or collapse. For example, the
recess can also serve as a space into which the cup-seal may
collapses, when the tool-string is retrieved from the well. The
concave side of the cup-seal(s) face toward the top of the well to
"catch" the fluid pumped down the upset tubing. In certain
preferred embodiments, the thickness of the cup is about 1/4'' to
1.2'' and the overall length of the cup is about 1-1/2'' to 3''
long. In embodiments, the forward and back edges of the cup-seal
are rounded or chamfered so as to prevent damage to the seal edges
when being run into or retracted from the well. This rounding or
chamfering of the cup-lip, helps assure they cup seal does not
become folded over when being retracted from the well. In certain
embodiments, the main body has an inner passageway through which
drilling fluid can pass toward the flexible tool-string. In some
preferred embodiments, the two ends of the main body make a "close
fit" (e.g. less than about 3/8''), to the inside diameter of the
upset tubing, so as to assure that the cup seal remains centralized
along the upset tubing axis.
[0061] Optionally, the slickline and e-line embodiments described
herein which entail fluid entering the radial drilling tool-string,
may incorporate a filter. This filter would be part of the
tool-string and would serve to prevent contaminants from entering:
the radial drilling tool-string; the downhole pump and/or the
flexible tool-string.
[0062] Optionally, in e-line embodiments using a downhole pump or
motor, the upset tubing may entail a one-way valve. By virtue of
this one-way valve fluid can enter the upset tubing from the
wellbore annulus but is prevented from moving from the upset tubing
to the wellbore annulus. The purpose of this one-way valve is to
allow for the creation of the piston affect by virtue of the
differential pressure across the seals. It is a further purpose of
the one-way valve to allow a closed-loop drilling system, by virtue
of the fact that the circulation path does not necessitate that
fluid be brought to the surface.
[0063] The various embodiments described herein are intended to
allow for the deployment of a variety of heads used to form the
hole in the casing and/or formation. For example, the head may
define a form of mechanical drill bit that is rotated by a motor.
Alternatively, the head may define a jetting nozzle that ejects
pressurized fluid to erode the formation. Likewise, the head may
define an apparatus that works by means of jet-assisted mechanical
drilling or is defined by a form of jet-assisted mechanical
drilling.
[0064] In the various embodiments utilizing a seal(s) for the
creation of the chamber and piston-affect, one can use fluid or gas
to generate the requisite differential pressure. Moreover, the
piston-affect can be aided by the slackening or loosening of the
control line. It should also be noted that the control lines have a
natural stretch to them, so it is not always mandatory to
deliberately slacken the control line. For example, if a
cutting-head is already drilling the wellbore casing on a
horizontal well, the operator can apply more WOB by merely
increasing the pressure on proximal (or top) side of the seal. In
this case, the increased force of the piston-affect can slightly
stretch the coiled-tubing, e-line or slickline, thereby allowing
for an increased in WOB. Of course, for continuous drilling of an
extended borehole, it will be necessary to advance the control line
with maintaining the piston-affect.
[0065] We now turn to a discussion of the placement of the seal(s).
In various embodiments, the seal(s) of this disclosure can be
placed in either a fixed position along the upset tubing; or, they
may be placed along on the downhole tool-string. In the cased where
the seals are placed in a fixed position, the radial drilling
tool-string essentially moves through the seal as it traverses the
upset tubing. Typically, in these fixed location embodiments,
multiple seals are positioned along the upset tubing forming a
series of successive series, whereby the piston-affect can remain
uninterrupted as the tool-string moves down the well. Notably,
these fixed position seals may only be necessary in slant or
horizontal section of a wells, as force of gravity alone is likely
sufficient in the vertical portion; and, if not, the weight bars
can be added to generate higher downward forces. In other
embodiments, the seal(s) would be attached to the tool-string
itself; and, would thereby move along the upset tubing as the
tool-string is moved in and out of the wellbore.
[0066] In e-line embodiments, the e-line conductor may serve as a
pathway for communicating the parameters or values of certain
downhole tool. In embodiments, the value reported to the surface
will be the torque value, such as by may be determined by a
downhole position sensor, transducer or load cell. In certain
embodiments, the e-line may be used to convey the WOB value, such
as might be attained from a pressure transducer or position sensor.
And, in embodiments, the value reported through the e-line may be
the annular pressure in the upset tubing above, below and/or across
the seal(s). In embodiments, reported value may be the pressure
reading may be of the fluid being pumped down the flexible
tool-string. Obviously, multiple values may be reported by the
e-line conductor.
[0067] Optionally, in coiled-tubing embodiments the means to create
the pressure in the chamber above the seal is a port-off apparatus.
In such embodiments, the port-off apparatus is part of the radial
drilling tool-string and would discharge a portion of the flow from
inside the coiled-tubing to the chamber. In this fashion the
chamber could be pressurized to generate the piston-affect, without
the need for pumping fluid from the surface down the upset tubing.
Moreover, in some embodiments, this port-off apparatus would define
a spring-loaded check valve or similar pressure drop device that
would limit the maximum pressure that could be built in the
chamber. For example, if the line pressure in the coiled-tubing
exceed the hydrostatic pressure by 750 lbs and the spring-loaded
check valve did not open until 375 lbs were applied, then the
pressure in the chamber could be regulated to only exceed
hydrostatic pressure by 375 psi. In this fashion, one can limit the
magnitude of the piston-affect.
[0068] In coiled-tubing embodiments the radial drilling system may
entail a conductor or fiber optical cable positioned in the
coiled-tubing. Alternatively, one may incorporate fluid pulses into
the fluid stream in the coiled-tubing. This can be done be changing
opening or closing a port and thereby changing the back-pressure on
the fluid--a value which can be measured at the surface. In
embodiments, the value reported from the downhole tool to the
surface will be the torque value such as by a may be reported by a
downhole position sensor, transducer or load cell. In embodiments,
this conductor cable or fiber-optic line may convey the WOB value,
such as might be attained from a pressure transducer or position
sensor. And, in embodiments, the value reported through the
conductor or fiber optic cable may be the pressure reading above
the seal, below the seal or across the seals.
[0069] In the narrative above, we have discussed various apparatus
and methods to deploy radial drilling tool-string using the
piston-affect to advance the tool-string into a well and/or apply
WOB. However, a similar piston-affect can also be used to help
retrieve the tool-string from a well in the event that it becomes
stuck or in order to reduce the amount of line-pull (tension)
required in the control-line. This can be done by bleeding-off the
pressure in the chamber above the seals (e.g. returning this fluid
to an open tank), while pumping fluid into the annulus of the
wellbore. By this method, once essentially creates the same
piston-affect, but in the opposite direction.
[0070] As evident from the figures, descriptions, and narrative,
the various embodiments of the present disclosure can be joined in
combination with other embodiments without deviating from the
spirit of this disclosure. Moreover, the figures and narrative are
not meant to limit the disclosure. That is, all combinations of
various embodiments of the disclosure are enabled, even if not
given in a particular example.
[0071] While illustrative embodiments have been depicted and
described, modifications thereof can be made by one skilled in the
art without departing from the scope of the disclosure. Moreover,
the indefinite articles "a" or "an", as used in the claims, are
defined herein to mean one or more than one of the element that it
introduces. For purposes of brevity and grammatic style, in certain
instances, the longer term "radial drilling tool-string" is
simplified by usage of the simpler term "tool-string". Similarly,
the term "head" may be used herein to denote a form of mechanical
cutting-head, jetting nozzle or other apparatus by which a hole in
the casing and/or earthen formation are formed. Furthermore, while
this disclosure typically utilizes the term "fluid", it is to be
understood the fluid may be fluid or gas. For example, one can
power the mud-motor with a gas such as nitrogen. If there is a
conflict in the usages of a word or term in this specification and
one or more patent or other documents, the definitions that are
consistent with this specification should be adopted. While
compositions and methods are described in terms of "comprising,"
"containing," or "including" various components or steps, the
compositions and methods can also "consist essentially of" or
"consist of" the various components and steps. The terms in the
claims have their plain, ordinary meaning unless otherwise
explicitly defined by the patentee.
[0072] Depending on the context, all references herein to the
"disclosure" may in some cases refer to certain specific
embodiments only. In other cases, it may refer to subject matter
recited in one or more, but not necessarily all, of the claims.
While the foregoing is directed to embodiments, versions and
examples of the present disclosure, which are included to enable a
person of ordinary skill in the art to make and use the disclosures
when the information in this patent is combined with available
information and technology, the disclosures are not limited to only
these particular embodiments, versions and examples.
[0073] Numerous other modifications, equivalents, and alternatives,
will become apparent to those skilled in the art once the above
disclosure is fully appreciated. While embodiments of the
disclosure have been shown and described, modifications thereof can
be made by one skilled in the art without departing from the
teachings of this disclosure. The embodiments described herein are
exemplary only, and are not intended to be limiting. Many
variations and modifications of the disclosure disclosed herein are
possible and are within the scope of the disclosure.
[0074] Use of the term "optionally" with respect to any element of
a claim is intended to mean that the subject element is required,
or alternatively, is not required. Both alternatives are intended
to be within the scope of the claim. It is intended that the
following claims be interpreted to embrace all such modifications,
equivalents, and alternatives where applicable. Other and further
embodiments, versions and examples of the disclosure may be devised
without departing from the basic scope thereof and the scope
thereof is determined by the claims that follow.
* * * * *