U.S. patent application number 13/669915 was filed with the patent office on 2013-05-09 for apparatus and process for drilling a borehole in a subterranean formation.
This patent application is currently assigned to Chevron U.S.A. Inc.. The applicant listed for this patent is George Taylor Armistead, Henry Anthony Bergeron. Invention is credited to George Taylor Armistead, Henry Anthony Bergeron.
Application Number | 20130112482 13/669915 |
Document ID | / |
Family ID | 48222949 |
Filed Date | 2013-05-09 |
United States Patent
Application |
20130112482 |
Kind Code |
A1 |
Armistead; George Taylor ;
et al. |
May 9, 2013 |
Apparatus and Process For Drilling A Borehole In A Subterranean
Formation
Abstract
An apparatus and process is disclosed for drilling a borehole
into a subterranean formation with reverse circulation of drilling
fluid. A tubular drill pipe extends into a subterranean formation.
A bottom hole assembly connected to the drill pipe includes a drill
bit for excavating the subterranean formation. A downhole motor is
adapted for receiving electrical power from a cable extending into
the subterranean formation. A downhole pump is powered by the motor
and is configured for reverse circulating drilling fluid from the
annular space surrounding the drill pipe to the interior space of
the drill pipe. The drilling fluid is pumped upwards in the drill
pipe by the downhole pump to carry excavated cuttings upwards
through the interior space of the drill pipe.
Inventors: |
Armistead; George Taylor;
(Katy, TX) ; Bergeron; Henry Anthony; (Houston,
TX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Armistead; George Taylor
Bergeron; Henry Anthony |
Katy
Houston |
TX
TX |
US
US |
|
|
Assignee: |
Chevron U.S.A. Inc.
San Ramon
CA
|
Family ID: |
48222949 |
Appl. No.: |
13/669915 |
Filed: |
November 6, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61556986 |
Nov 8, 2011 |
|
|
|
Current U.S.
Class: |
175/57 ;
175/104 |
Current CPC
Class: |
E21B 4/04 20130101; E21B
21/085 20200501; E21B 21/08 20130101; E21B 7/15 20130101 |
Class at
Publication: |
175/57 ;
175/104 |
International
Class: |
E21B 4/04 20060101
E21B004/04; E21B 21/00 20060101 E21B021/00; E21B 7/24 20060101
E21B007/24 |
Claims
1. An apparatus for drilling a borehole into a subterranean
formation with reverse circulation of drilling fluid, the apparatus
comprising: (a) a tubular drill pipe extending into the
subterranean formation, the drill pipe having an interior space and
an annular space on the exterior of the drill pipe; (b) a bottom
hole assembly connected to the drill pipe, the bottom hole assembly
comprising a bit to excavate the subterranean formation to form
cuttings; (c) a downhole motor, the downhole motor being adapted
for receiving electrical power from a cable extending into the
subterranean formation; and (d) a downhole pump powered by the
motor, the downhole pump being configured for reverse circulating
drilling fluid and cuttings upwards through the interior space of
the drill pipe.
2. The apparatus of claim 1 further comprising a mechanism for
removing the excavated cuttings from the drilling fluid and
recirculating the drilling fluid downwards through the annular
space on the exterior of the drill pipe.
3. The apparatus of claim 1 wherein the bit comprises a rotary rock
bit.
4. The apparatus of claim 1 wherein the bit comprises one or more
electrodes configured for applying a pulsed voltage to excavate the
formation with applied pulsed power.
5. The apparatus of claim 1 wherein the downhole pump is a positive
displacement pump.
6. The apparatus of claim 1 wherein the bit does not rotate.
7. The apparatus of claim 1 wherein the cross sectional area of the
interior space of the drill pipe is less than the cross sectional
area of the annular space, thereby minimizing the drilling fluid
flow rate that is required to carry excavated cuttings upwards
through the interior space of the drill pipe.
8. The apparatus of claim 1 further comprising a downhole generator
for applying pulsed power to the bit.
9. The apparatus of claim 1 wherein the drilling fluid comprises an
electrically insulating formulation having a low level of
electrical conductivity.
10. The apparatus of claim 9 wherein the drilling fluid comprises a
carbon-based material.
11. A process for drilling a borehole into a subterranean formation
with reverse circulation of drilling fluid, the process comprising
the steps of: (a) extending a tubular drill pipe into the
subterranean formation, the drill pipe having an interior space and
an annular space on the exterior of the drill pipe, the drill pipe
having a proximal end near the top of the wellbore and a distal end
with an attached bottom hole assembly, the bottom hole assembly
comprising a bit; (b) excavating the formation with the bit to form
cuttings; (c) providing a pump and a motor in the borehole, the
pump being powered by the motor, the pump being in fluid
communication with the interior of the drill pipe; (d) circulating
drilling fluid from the annular space to the interior space of the
drill pipe; and (e) pumping drilling fluid with cuttings upwards
through the interior space of the drill pipe.
12. The process of claim 11 further comprising the step of: (f)
removing excavated cuttings from the drilling fluid near the top of
the wellbore; and (g) recirculating the drilling fluid downward
through the annular space.
13. The process of claim 11 wherein the bit comprises one or more
electrodes, further wherein the excavating step (b) comprises
applying a pulsed voltage to one or more electrodes to excavate the
subterranean formation.
14. The process of claim 11 wherein the pump is a positive
displacement pump.
15. The process of claim 11 wherein the bit is a rotary rock bit,
the process comprising the additional step of rotating the rotary
rock bit to excavate the formation.
16. The process of claim 11 wherein the cross sectional area of the
interior space of the drill pipe is less than the cross sectional
area of the annular space, thereby minimizing the drilling fluid
flow rate required to carry excavated cuttings upwards through the
interior space of the drill pipe.
17. The process of claim 13 further comprising a downhole generator
for applying pulsed voltage to the bit.
18. The process of claim 13 wherein the drilling fluid comprises an
electrically insulating formulation having a low level of
electrical conductivity.
19. The process of claim 18 wherein the drilling fluid comprises a
carbon-based material.
20. The process of claim 13 wherein a control system is employed to
regulate the pulse repetition rate of the electrodes.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to and relates to an
earlier filed U.S. provisional application Ser. No. 61/556,986
which was filed in the United States Patent and Trademark Office on
Nov. 8, 2011.
FIELD OF THE INVENTION
[0002] The field of the invention is directed to apparatus and
processes for drilling a well by employing reverse circulation of
drilling fluid.
BACKGROUND OF THE INVENTION
[0003] When conducting drilling to construct deep wells, the
pressure of drilling fluid or drilling mud that is pumped down from
the surface and into the open hole of the formation may be quite
high. It is usually advisable to maintain a fluid/mud weight above
the formation pressure to prevent gas "kicks" or influxes from the
wellbore. Furthermore, the friction pressure of pumping into a
drill string may be quite substantial. Thus, pressure is required
to be applied to cause the drilling fluid and cuttings to flow
through the drill string, out into the open hole, and up the
annulus at an adequate rate.
[0004] Too much pressure applied in this process can cause other
problems. That is, such fluid pressure applied at the surface also
is applied to the open hole of the subterranean formation. High
pressures applied to an open hole of a formation may cause the
formation to fracture, with a subsequent sudden loss of drilling
fluid into the formation. Such a sudden loss of drilling fluid into
the formation may have severe consequences. In some instances,
there is a very narrow "window" of pressure that may properly be
applied in the drilling of a well without exerting too much or too
little pressure. That is, excess applied pressure can fracture the
formation. On the other hand, inadequate pressure may not properly
carry the drilled cuttings up the annulus to the surface. Thus, a
pressure "window" exists that engineers must observe in planning
the pressure to exert while drilling a well.
[0005] Sometimes, lost circulation materials or pills are applied
into drilling fluid, and such materials travel out of the bit and
adhere to the formation to prevent such fluid loss into the
formation. But, such materials may damage the formation and reduce
the ability of the formation subsequently to produce oil and gas
into the wellbore during production operations. Such damage to the
formation is undesirable, and therefore the use of such materials
is not always advisable.
[0006] Operating within the mud weight "window" allows engineers to
improve drilling efficiency and set casing at the best possible
depth. If casing is set too shallow, well construction cost
increases and well depth is limited. Sometimes, this may cause the
production rate to be compromised. In other instances, the target
formation may not be accessible. Techniques that widen or open the
window to be employed are desirable.
[0007] Conventional drilling employs rotary rock bits to compress
the rock, causing the rock to fracture into cuttings. Pulsed power
drilling, however, is a method of constructing a wellbore by
applying voltage into the rock of a formation, which causes the
rock to fail in tension rather than compression. High voltage
pulses employed in pulsed power drilling may cause an electrical
arc in the rock that causes the rock to break in an
electro-crushing process. One illustration of such a drilling
technique is described in U.S. Patent Publication No. US
2009/0050371 A1 to Moeny et al. (See "Moeny"). In such
applications, drilling fluid flows down the drill string and out
through passages in the bit near the electrodes and then up the
outside of the drilling apparatus within the annulus to bring rock
cuttings to the surface. (US 2009/0050371 A1, paragraph 0109).
[0008] A technique or apparatus that is capable of reducing the
risk of formation damage and allowing the use of a reduced bottom
hole pressure in the drilling of deep wells would be very
desirable. A drilling technique that is capable of allow cuttings
to be brought to the surface using a reduced flow rate of flow of
drilling fluid is highly desirable.
[0009] The invention is directed to improved drilling apparatus and
processes.
SUMMARY OF THE INVENTION
[0010] An apparatus and process for drilling a borehole into a
subterranean formation with reverse circulation of drilling fluid
is provided. The apparatus employs a means to transfer a supply of
electrical power downhole either from a cable running down the
bottom hole assembly components or the use of "wired drill pipe"
with the capability to conduct electrical energy downhole with
electrical conductors incorporated into the drill pipe body. The
apparatus comprises a tubular drill pipe extending into the
subterranean formation, the drill pipe having an interior space and
an annular space on the exterior of the drill pipe. A bottom hole
assembly is connected to the drill pipe, the bottom hole assembly
comprising a bit to excavate the subterranean formation to form
cuttings. A downhole motor is provided, the downhole motor being
adapted for receiving electrical power from either the cable
extending into the subterranean formation or the use of wired drill
pipe supplying the electrical power. A downhole pump is powered by
the motor, the downhole pump being configured for reverse
circulating drilling fluid and cuttings upwards through the
interior space of the drill pipe.
[0011] In one embodiment of the invention, the apparatus comprises
a mechanism for removing excavated cuttings from the drilling fluid
and then recirculating the drilling fluid downwards through the
annular space on the exterior of the drill pipe. The bit may
comprise a rotary rock bit. In other applications, the apparatus
may have one or more electrodes configured for applying a pulsed
voltage to excavate the formation with applied pulsed power. The
downhole pump may be a positive displacement pump. In some
applications, such as certain pulsed power bit applications, the
bit may not rotate.
[0012] In some embodiments of the invention, the cross sectional
area of the interior space of the drill pipe is less than the cross
sectional area of the annular space, thereby minimizing the
drilling fluid flow rate that is required to carry excavated
cuttings upwards through the interior space of the drill pipe.
[0013] A downhole generator may be provided, in one embodiment of
the invention, for applying pulsed power to the bit. The drilling
fluid may comprise an electrically insulating formulation having a
low level of electrical conductivity. In some applications, the
drilling fluid comprises a carbon-based material.
[0014] A process is disclosed for drilling a borehole into a
subterranean formation with reverse circulation of drilling fluid.
The process comprises extending a tubular drill pipe into the
subterranean formation, the drill pipe having an interior space and
an annular space on the exterior of the drill pipe, the drill pipe
having a proximal end near the top of the wellbore and a distal end
with an attached bottom hole assembly. An electrical cable or wired
drill pipe extends into the well to supply power to downhole
apparatus. The bottom hole assembly may comprise a drilling bit. A
pump and a motor are provided within the borehole, the pump being
powered by the motor. The pump is in fluid communication with the
interior of the drill pipe. It may be possible to circulate
drilling fluid from the annular space to the interior space of the
drill pipe. Drilling fluid with cuttings may be pumped upwards
through the interior space of the drill pipe. In some embodiments
of invention, excavated cuttings may be removed from the drilling
fluid near the top of the wellbore and re-circulated downward
through the annular space. A control system may be employed to
regulate the pulse repetition rate of the electrodes.
BRIEF DESCRIPTION OF THE FIGURES
[0015] Figures are provided to illustrate specific embodiments of
the invention, but the invention is not limited to only the
embodiments illustrated in the Figures, but may extend to other
variations that would be appreciated by a person of skill in the
art of drilling.
[0016] FIG. 1 illustrates a schematic of one embodiment of the
invention that employs a pulsed power drilling bit;
[0017] FIG. 1A shows a perspective view of the pulsed power
drilling bit employed in the apparatus of FIG. 1;
[0018] FIG. 2 shows an alternate embodiment of the invention with a
drilling apparatus that employs a rotary rock drill bit; and
[0019] FIG. 2A shows a more detailed view of the rotary rock drill
bit.
DETAILED DESCRIPTION OF THE INVENTION
[0020] The present invention may employ pulsed power drilling
apparatus or rotary rock drilling apparatus with reverse
circulation drilling. Reverse circulation drilling refers to
drilling wherein the drilling fluid is passed down the annulus to
the outside of the drill string or drill pipe, and then circulated
upwards through the drill pipe towards the upper end of the
wellbore.
[0021] As used herein, "drilling" is defined as excavating or
otherwise breaking and driving through a subterranean formation
substrate. As used herein, "bit" and "drill bit" are defined as the
working portion or end of a tool for providing cutting, drilling,
boring, or breaking action on a substrate, such as rock. As used
herein, the term "pulsed power" is that which results when
electrical energy is stored (e.g., in a capacitor or inductor) and
then released so that a pulse of current at high peak power is
produced.
[0022] Referring to FIG. 1, a drilling apparatus 18 is disclosed
for entry into a wellbore 19 of a subterranean formation 20. A
tubular drill pipe 22 is provided with an interior space 24 inside
the pipe, and an annular space 26 outside the drill pipe 22. A
bottom hole assembly 28 is connected to the drill pipe 22 and is
located, during drilling, at the lower portion of the wellbore 19.
A bit 30 is configured to contact and break the rock of
subterranean formation 20. FIG. 1 shows a pulsed power bit 30, but
other bits may be employed as further described herein. Drilling
fluid is circulated in reverse flow direction, such that the fluid
with cuttings flows along direction arrow 40, and then along
direction arrow 32. Cuttings are dislodged by the bit 30 and
transferred by way of drilling fluid along arrow 32 to upwards in
the wellbore 19. A cable 36 is provided for providing a steady
source of electricity to downhole motor 34, which drives downhole
pump 38 to move the drilling fluid.
[0023] FIG. 1A shows a perspective view of the bit 30, which in the
embodiment of FIG. 1A is a pulsed power bit 30. For drilling larger
holes, a conical bit may be employed, especially if controlling the
direction of the hole is a primary concern. Such a bit 30 may
comprise one or more sets of electrodes for creating the
electro-crushing arcs and may optionally comprise mechanical teeth
to assist the electro-crushing process. One embodiment of the
conical electro-crushing bit has a single set of electrodes
arranged coaxially on the bit, as shown in FIG. 2A. In this
embodiment, conical bit 30 comprises a center electrode 48, the
surrounding electrode 44, the housing 42 and mechanical teeth 46
for drilling the rock. Either or both electrodes may be
compressible. The surrounding electrode may have mechanical cutting
teeth 50 incorporated into the surface to smooth over the rough
rock texture produced by the electro-crushing process. In this
particular embodiment of the invention, the inner portion of the
hole is drilled by the electro-crushing portion (i.e., electrodes
48 and 44) of the bit 30, and the outer portion of the hole is
drilled by mechanical teeth 46. This results in high drilling
rates, because the mechanical teeth have good drilling efficiency
at high velocity near the perimeter of the bit, but very low
efficiency at low velocity near the center of the bit. The
geometrical arrangement of the center electrode 48 to the ground
ring electrode 44 is conical. It should be recognized that many
types of pulsed power bit configurations could be employed in the
practice of the invention, and the invention is not limited to only
the configuration shown in FIG. 1A. U.S. Patent Publication No. US
2009/0050371 A1 to Moeny et al. (See "Moeny") describes various
embodiments and technical specifications that may be employed in
the application of pulsed power drilling, and is incorporated
herein by reference. Further, other pulsed power drilling apparatus
and techniques may be employed. Other embodiments of the invention
may employ rotary rock bits that do not employ pulsed power, as
further described herein in connection with FIGS. 2 and 2A.
[0024] FIG. 2 shows an alternate embodiment of the invention of
drilling apparatus 60 that employs a rotary rock bit to break the
rock to form a borehole by compression upon the rock within
subterranean formation 77. In this embodiment, a tubular drill pipe
52 comprises an interior space 72 and an annular space 70 on the
exterior of the drill pipe 52. A power cable 54 extends into the
wellbore 53 and supplied electrical power to downhole motor 56,
which drives downhole pump 58, which transports drilling fluid. A
bottom hole assembly 62 is positioned upon the end of drill pipe
52, and comprises a bit 64. In the embodiment of FIG. 2, the bit 64
is a rotary rock bit. A reverse circulation process is employed to
circulate the drilling fluid along direction arrow 66 and then into
the interior space 72 of the drill pipe 52. Drilling fluid picks up
rock cuttings generated by bit 64 and transports them along
direction arrow 68 and arrow 74 upwards in drill pipe 52 in a
reverse circulation flow direction.
[0025] FIG. 2A illustrates rotary rock bit 64, which in this
particular example is a tricone style bit 64. The bit 64 has teeth
76 for contact with rock of the subterranean formation 77.
[0026] As described previously, in the first illustrated embodiment
of the present invention, as shown in FIGS. 1 and 1A, a drill bit
is provided upon which is disposed one or more sets of electrodes.
In this particular embodiment, the electrodes are disposed so that
a gap is formed between them and the electrodes are disposed on the
drill bit so that they are oriented along a face of the drill bit.
Electrodes between which an electrical current passes through a
mineral substrate (e.g., rock) are not on opposite sides of the
rock. Also, in this embodiment, it is not necessary that all
electrodes touch the mineral substrate as the current is being
applied.
[0027] The electrodes of the embodiments shown in FIGS. 1-1A are
disposed on a bit and arranged such that electro-crushing arcs are
created in the rock. High voltage pulses are applied repetitively
to the bit to create repetitive electro-crushing excavation events.
Electro-crushing drilling can be accomplished, for example, with a
flat-end cylindrical bit with one or more electrode sets. These
electrodes can be arranged in a coaxial configuration, as one
example.
[0028] The electrocrushing drilling process does not require
rotation of the bit, but in some instances bit rotation may be
desirable. The electro-crushing drilling process is capable of
excavating the hole beyond the edges of the bit without the need of
mechanical teeth. In addition, by arranging many electrode sets at
the front of the bit and varying the pulse repetition rate or pulse
energy to different electrode sets.
[0029] The invention may be provided in other arrangements not
specifically shown or described in this specification but within
the general spirit and scope of the invention.
* * * * *