U.S. patent application number 10/785456 was filed with the patent office on 2005-03-03 for method of forming a bore.
Invention is credited to Burge, Philip Michael, Hewson, James Adam.
Application Number | 20050045340 10/785456 |
Document ID | / |
Family ID | 34203647 |
Filed Date | 2005-03-03 |
United States Patent
Application |
20050045340 |
Kind Code |
A1 |
Hewson, James Adam ; et
al. |
March 3, 2005 |
Method of forming a bore
Abstract
A method of forming a supported subterranean well bore in which,
in one disclosed embodiment, a first drill bit is mounted on a
first string of casing tubulars via a steerable tool, and the drill
bit is used to form a first bore. Upon reaching the required depth
the casing string is cemented in place to support the formed bore
and a second drill bit is mounted on a second casing string and is
inserted into the first casing string. The second drill bit is used
to drill through the wall of the first casing string and proceed to
form a second, deeper bore. Once the second drill bit has reached
the required depth, the second casing string is cemented in place
to support the second bore.
Inventors: |
Hewson, James Adam;
(Aberdeen, GB) ; Burge, Philip Michael;
(Aberdeenshire, GB) |
Correspondence
Address: |
GIFFORD, KRASS, GROH, SPRINKLE
ANDERSON & CITKOWSKI, PC
280 N OLD WOODARD AVE
SUITE 400
BIRMINGHAM
MI
48009
US
|
Family ID: |
34203647 |
Appl. No.: |
10/785456 |
Filed: |
February 24, 2004 |
Current U.S.
Class: |
166/380 ;
175/171 |
Current CPC
Class: |
E21B 33/14 20130101;
E21B 43/103 20130101; E21B 29/06 20130101; E21B 7/20 20130101 |
Class at
Publication: |
166/380 ;
175/171 |
International
Class: |
E21B 029/10 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 1, 2003 |
GB |
0320408.8 |
Claims
1. A method of forming a supported bore comprising the steps of:
mounting a first drill bit on a first tubular member; drilling a
first bore to a first depth; inserting a second drill bit mounted
on a second tubular member within the first tubular member; and
directing the second drill bit towards a wall portion of the first
tubular member and drilling through said wall portion and drilling
a second bore to a second depth.
2. A drilling assembly comprising a first drill bit mounted on a
first tubular member and a second drill bit mounted on a second
tubular member, wherein at least said first tubular member includes
a deflecting member mounted therein.
3. A method of forming a supported bore as claimed in claim 1,
wherein the first tubular member is fixed in place in the first
bore before the second bore is drilled.
4. A method of forming a supported bore as claimed in claim 1,
wherein the first tubular member is fixed in place in the first
bore after the second bore is drilled.
5. A method of forming a supported bore as claimed in claim 3,
wherein the first tubular member is cemented in place in the first
bore.
6. A method of forming a supported bore as claimed in claim 1,
wherein the second tubular member is fixed in place within the
second bore.
7. A method of forming a supported bore as claimed in claim 6,
wherein the second tubular member is cemented in place within the
second bore.
8. A method of forming a supported bore as claimed in claim 1,
wherein the second drill bit is directed towards the wall portion
of the first tubular member by use of a deflecting member mounted
within the first tubular member.
9. A method of forming a supported bore as claimed in claim 1,
wherein the first drill bit is located on a steerable tool before
being mounted on the first tubular member in order to provide the
first drill bit and tubular member with directional drilling
capability.
10. A method of forming a supported bore as claimed in claim 1,
wherein the method is adapted for use in producing a supported bore
which extends from surface level and intersects a subterranean
hydrocarbon bearing formation.
11. A method of forming a supported bore as claimed in claim 1,
wherein the supported bore is a deviated bore.
12. A method of forming a supported bore as claimed in claim 1,
wherein the supported bore is a multilateral bore.
13. A method of forming a supported bore as claimed in claim 1,
wherein the second drill bit is located on a steerable tool in
order to provide the second drill bit and tubular member with
directional drilling capability.
14. A method of forming a supported bore as claimed in claim 9,
wherein the steerable tool is a mechanical device that can be
adjusted to effect changes in bore direction.
15. A method of forming a supported bore as claimed in claim 8,
wherein the deflecting member is set at a chosen angle with respect
to the longitudinal axis of the first tubular member.
16. A method of forming a supported bore as claimed in claim 15,
wherein the deflecting member is set at an angle of between 0.5 and
5 degrees with respect to the longitudinal axis of the first
tubular member.
17. A method of forming a supported bore as claimed in claim 8,
wherein the deflecting member is fixed relative to the first
tubular member.
18. A method of forming a supported bore as claimed in claim 8,
wherein the deflecting member includes a hardened surface to
deflect the second drill bit towards the wall of the first tubular
member and to prevent the member from being destroyed by the second
drill bit.
19. A method of forming a supported bore as claimed in claim 8,
wherein the deflecting member defines at least one fluid
communicating aperture which allows the flow of fluids through and
past the deflecting member.
20. A method of forming a supported bore as claimed in claim 8,
wherein the deflecting member is a whipstock.
21. A method of forming a supported bore as claimed in claim 8,
wherein the deflecting member is a kick-off plate.
22. A method of forming a supported bore as claimed in claim 8,
wherein the portion of the wall of the first tubular member
opposing the deflecting member is of a reduced hardness relative to
the remaining portion of the first tubular member.
23. A method of forming a supported bore as claimed in claim 22,
wherein the portion of the wall of the first tubular member
opposing the deflecting member is composed of a relatively soft
metallic material.
24. A method of forming a supported bore as claimed in claim 22,
wherein the portion of the wall of the first tubular member
opposing the deflecting member is composed of a composite
material.
25. A method of forming a supported bore as claimed in claim 1,
wherein the first tubular member comprises at least one casing
tubular.
26. A method of forming a supported bore as claimed in claim 1,
wherein the first tubular member comprises a plurality of casing
tubulars.
27. A method of forming a supported bore as claimed in claim 1,
wherein the first tubular member comprises at least one liner
tubular.
28. A method of forming a supported bore as claimed in claim 1,
wherein the second tubular member comprises a plurality of casing
tubulars.
29. A method of forming a supported bore as claimed in claim 1,
wherein the second tubular member comprises a plurality of liner
tubulars.
30. A method of forming a supported bore as claimed in claim 1,
wherein the second tubular member comprises a plurality of drilling
tubulars.
31. A method of forming a supported bore as claimed in claim 1,
wherein the second tubular member comprises a plurality of drilling
collars.
32. A method of forming a supported bore as claimed in claim 1,
wherein rotation of the drill bit to effect drilling is provided by
corresponding rotation of the tubular member upon which it is
mounted.
33. A method of forming a supported bore as claimed in claim 1,
wherein rotation of the drill bit is achieved by use of a downhole
drive unit.
34. A method of forming a supported bore as claimed in claim 33,
wherein the downhole drive unit is a positive displacement mud
motor.
35. A method of forming a supported bore as claimed in claim 1,
wherein the first tubular member includes a valve assembly for
preventing fluids which are located in an annulus outwith the first
tubular member from flowing or being displaced into the tubular
member.
36. A method of forming a supported bore as claimed in claim 35,
wherein the valve assembly is a collar having a selectively
closable fluid communicating throughbore.
37. A method of forming a supported bore as claimed in claim 35,
wherein the valve assembly is a float collar.
38. A method of forming a supported bore as claimed in claim 35,
wherein the valve assembly is located above the deflecting
member.
39. A method of forming a supported bore as claimed in claim 1,
wherein the second tubular member includes a valve assembly for
preventing fluids which are located in an annulus outwith the
second tubular member from flowing or being displaced into the
tubular member.
40. A method of forming a supported bore as claimed in claim 39,
wherein the valve assembly is a collar having a selectively
closable fluid communicating throughbore.
41. A method of forming a supported bore as claimed in claim 35,
wherein the valve assembly is a float collar.
42. A method of forming a supported bore as claimed in claim 35,
wherein the valve assembly defines a throughbore allowing fluids
such as cement or drilling fluid which are pumped through the
tubular members to pass therethrough.
43. A method of forming a supported bore as claimed in claim 42,
wherein the throughbore of the valve assembly is selectively
closed.
44. A method of forming a supported bore as claimed in claim 43,
wherein the throughbore of the valve assembly is selectively closed
by a plug or dart provided from surface level.
45. A method of forming a supported bore as claimed in claim 43,
wherein the throughbore is closed by a flapper valve.
46. A method of forming a supported bore as claimed in claim 43,
wherein the throughbore is closed by a ball valve.
47. A method of forming a supported bore as claimed in claim 1,
wherein the first tubular member includes means for determining at
least one parameter of the bore.
48. A method of forming a supported bore as claimed in claim 1,
wherein the second tubular member includes a deflecting member and
means for determining at least one parameter of the bore.
49. A method of forming a supported bore as claimed in claim 47,
wherein the means for determining at least one parameter of the
bore include a data acquisition apparatus.
50. A method of forming a supported bore as claimed in claim 49,
wherein the data acquisition apparatus is a bore logging
apparatus.
51. A method of forming a supported bore as claimed in claim 49,
wherein the data acquisition apparatus performs data acquisition
while the bore is being drilled.
52. A method of forming a supported bore as claimed in claim 49,
wherein a landing joint is provided on a portion of the
corresponding tubular member in order to provide a means for
locating the data acquisition apparatus within the corresponding
tubular member, and also for allowing the acquisition apparatus to
be retrieved from within the tubular member.
53. A method of forming a supported bore as claimed in claim 52,
wherein the landing joint landing joint is located above the
deflecting member and: is located in a fixed position relative
thereto such that the orientation of the deflecting member, and
thus the deflection angle, may be ascertained by the data
acquisition apparatus.
54. A method of forming a supported bore as claimed in claim 49,
wherein any data acquisition apparatus located within a
corresponding tubular member is retrieved before the tubular member
is fixed in place within the bore.
55. A method of forming a supported bore as claimed in claim 1,
wherein the first tubular member further includes means for
determining the orientation of the first drill bit.
56. A method of forming a supported bore as claimed in claim 55,
wherein the orientation of the first drill bit may be determined by
use of the data acquisition apparatus.
57. A method of forming a supported bore as claimed in claim 55,
wherein the orientation of the first drill bit may be achieved by
use of a Measurement While Drilling (MWD) apparatus.
58. A method of forming a supported bore as claimed in claim 55,
wherein where the drill bit is located on the steerable tool, the
steerable tool includes include means for directly or indirectly
determining the orientation of the first drill bit.
59. A method of forming a supported bore as claimed in claim 1,
wherein the second tubular member includes means for determining
the orientation of the second drill bit.
60. A method of forming a supported bore as claimed in claim 59,
wherein the orientation of the second drill bit may be achieved by
use of a Measurement. While Drilling (MWD) apparatus.
61. A method of forming a supported bore as claimed in claim 59,
wherein where the second drill bit is located on a steerable tool,
the steerable tool includes include means for directly or
indirectly determining the orientation of the second drill bit.
62. A method of forming a supported bore as claimed in claim 59,
wherein the orientation of the second drill bit may be achieved by
use of a Logging While Drilling (LWD) apparatus.
63. A method of forming a supported bore comprising the steps of:
locating a first drill bit on a steerable tool and mounting the
steerable tool and first drill bit on a first tubular member, said
first tubular member including a deflecting member and means for
determining at least one parameter of the bore and the orientation
of the drill bit; drilling a first bore to a first depth; inserting
a second drill bit mounted on a second tubular member within the
first tubular member; and drilling through a wall portion of the
first tubular member at the location of the deflecting member and
drilling a second bore to a second depth.
64. A method of forming a supported bore, said method comprising
the steps of: locating a first drill bit on a first expandable
tubular member having an upper portion of a first diameter and a
lower portion of a second, larger diameter; drilling a bore with
the drill bit mounted on the first expandable tubular member;
pumping cement into an annulus formed between the expandable
tubular member and the wall of the bore; and expanding the upper
portion of the tubular member to a third diameter, greater than the
first diameter.
65. The method of claim 64, wherein the third diameter is
substantially equal to the second diameter.
66. A method of forming a supported bore as claimed in claim 64,
wherein the upper portion of the tubular member is expanded by use
of an expansion mandrel forced through the tubular member.
67. A method of forming a supported bore as claimed in claim 66,
wherein the mandrel is moved in an upwards direction to expand the
tubular member.
68. A method of forming a supported bore as claimed in claim 66,
wherein the mandrel is moved in a downwards direction to expand the
tubular member.
69. A method of forming a supported bore as claimed in claim 66,
wherein the mandrel is substantially conical.
70. A method of forming a supported bore as claimed in claim 64,
wherein the tubular member includes a valve member defining a
throughbore through which fluid may pass.
71. A method of forming a supported bore as claimed in claim 70,
wherein the valve member is a collar.
72. A method of forming a supported bore as claimed in claim 70,
wherein the valve member is a float collar.
73. A method of forming a supported bore as claimed in claim 66,
wherein the mandrel defines a fluid transmitting throughbore
providing a passage for fluid.
74. A method of forming a supported bore as claimed in claim 70,
wherein the mandrel is initially located within the lower portion
of the tubular member above the valve member.
75. A method of forming a supported bore as claimed in claim 70,
wherein the throughbore in the valve member is closable to form a
chamber between the valve member and the mandrel.
76. A method of forming a supported bore as claimed in claim 75,
wherein the throughbore in the valve member is closed by a plug or
dart provided from surface.
77. A method of forming a supported bore as claimed in claim 75,
wherein the throughbore in the valve member is closed by a flapper
valve.
78. A method of forming a supported bore as claimed in claim 75,
wherein the throughbore in the valve member is closed by a ball
valve.
79. A method of forming a supported bore as claimed in claim 75,
wherein the method further comprises the step of pressurising the
chamber formed between the mandrel and the valve member, such that
the mandrel is forced through the tubular member to effect
expansion of the tubular member.
80. A method of forming a supported bore as claimed in claim 79,
wherein by initially pressurising the chamber, the throughbore in
the mandrel is closed.
81. A method of forming a supported bore as claimed in claim 80,
wherein the throughbore in the mandrel is closed by use of a one
way pressure valve.
82. A method of forming a supported bore as claimed in claim 80,
wherein the throughbore in the mandrel is closed by use of a
flapper valve.
83. A method of forming a supported bore as claimed in claim 79,
wherein the chamber is pressurised with a fluid provided from
surface, which fluid is pumped through the mandrel and into the
chamber.
84. A method of forming a supported bore as claimed in claim 75,
wherein the mandrel comprises a pumping mechanism to pump fluid
into the chamber.
85. A method of forming a supported bore as claimed in claim 75,
wherein a separate pumping unit is utilised to pump fluid into the
chamber.
86. A method of forming a supported bore as claimed in claim 85,
wherein the separate pumping unit is located adjacent the
mandrel.
87. A method of forming a supported bore as claimed in claim 86,
wherein the separate pumping unit is located at surface level.
88. A method of forming a supported bore as claimed in claim 66,
comprising creating a pressure differential across the mandrel to
urge the mandrel through the tubular mandrel.
89. A method of forming a supported bore as claimed in claim 88,
wherein pressurised fluid is supplied from surface to create said
pressure differential.
90. A method of forming a supported bore as claimed in claim 88,
comprising running in a further tubular member to engage the
mandrel and supplying pressurised fluid via the further tubular
member.
91. A method of forming a supported bore as claimed in claim 90,
comprising running said further tubular member following drilling
of the bore.
92. A method of forming a supported bore as claimed in claim 66,
wherein the mandrel is forced through the tubular member by pulling
from the surface.
93. A method of forming a supported bore as claimed in claim 92,
wherein the mandrel is pulled through the tubular member by use of
a support member.
94. A method of forming a supported bore as claimed in claim 93,
wherein the support member is run in following drilling of the
bore.
95. A method of forming a supported bore as claimed in claim 93,
wherein the support member is a reelable support.
96. A method of forming a supported bore as claimed in claim 93,
wherein the support member is a drill pipe string.
97. A method of forming a supported bore as claimed in claim 66,
wherein the mandrel is removed from the tubular member once the
tubular member has been expanded.
98. A method of forming a supported bore as claimed in claim 64,
wherein the method further comprises the step of inserting a second
drill bit mounted on a second tubular member within the first
tubular member after said first tubular member has been expanded
and drilling through a wall portion of the first tubular member and
subsequently drilling a second bore.
99. A method of forming a supported bore as claimed in claim 98,
wherein once the second bore is drilled to the required depth,
cement is pumped into an annulus formed between the wall of the
second bore and the second tubular member.
100. A method of forming a supported bore as claimed in claim 98,
wherein the first expandable tubular member includes a deflecting
member, which deflecting member, in use, deflects or guides the
second drill bit towards a wall portion of the first tubular member
to be drilled.
101. A method of forming a supported bore as claimed in claim 100,
wherein the deflection member is located below the valve member and
the mandrel.
102. A method of forming a supported bore as claimed in claim 98,
wherein the second tubular member is expandable and a portion
thereof may be expanded to a larger diameter once the second bore
has been drilled to the required depth.
103. A method of forming a supported bore as claimed in claim 102,
wherein the second tubular member is expanded before cement is
pumped into the annulus between the second bore wall and the second
tubular member.
104. A method of forming a supported bore as claimed in claim 102,
wherein the second tubular member is expanded after cement is
pumped into the annulus.
105. A method of forming a supported bore as claimed in claim 64,
wherein the volume of cement pumped into the annulus is selected
such that the annulus is substantially filled with cement when the
upper portion of the expandable tubular member has been
expanded.
106. A method of forming a supported bore comprising the steps of:
locating a first drill bit on a steerable tool and mounting the
steerable tool and first drill bit on a first expandable tubular
member, said first expandable tubular member including a deflecting
member and means for determining at least one parameter of the bore
and the orientation of the drill bit; drilling a first bore to a
first depth; pumping cement into an annulus formed between the
first tubular member and the wall of the first bore; expanding a
portion of the first expandable tubular member to a larger
diameter; inserting a second drill bit mounted on a second tubular
member within the first tubular member; drilling through a wall
portion of the first tubular member at the location of the
deflecting member and drilling a second bore to a second depth; and
cementing the second tubular member in place within the second
bore.
107. A drilling assembly comprising a first drill bit mounted on a
first expandable tubular member, wherein said first expandable
tubular member includes an upper portion of a first diameter and a
lower portion of a second, larger diameter.
Description
[0001] The present invention relates to a method of forming a
supported bore, and in particular, but not exclusively, to a method
of forming a subterranean well bore. The present invention also
relates to an apparatus for forming a supported bore.
[0002] In the oil and gas exploration and extraction industry,
hydrocarbons contained within subterranean formations are accessed
and flowed to surface via well bores drilled from surface to
intersect the formations. Conventional methods of producing a well
bore involve a staged process. Initially, a bore section is drilled
using a drill bit mounted on a drill string comprising a
combination of drilling pipes and collars, which are used to impart
rotation and weight to the drill bit. After a certain depth,
however, the walls of the bore are likely to become unstable and
will eventually collapse if unsupported. Thus, to prevent collapse,
the next stage involves pulling the drill bit and the drill string
out of the hole to allow a supporting structure to be set in place.
Often a bore will be drilled to a depth of between 610 to 915 m
(2000 to 3000 ft) before support is provided. Thus, pulling the
drill string out of the hole is extremely time consuming,
considering that conventional drilling rigs and platforms can
accommodate dismantling and storage of the drill string in lengths,
known as "stands", of approximately 27.5 m (90 ft).
[0003] As noted above, once the drill bit and drill string have
been removed from the hole a supporting structure is set in place.
The supporting structure, generally referred to as the casing or
liner, comprises a number of casing tubulars or liner tubulars
which are normally coupled together by threaded connectors and
extend to the bottom of the hole. Once the casing or liner is run
into the bore, a cement slurry is pumped into the annulus formed
between the wall of the bore and the casing, which cement cures to
set and seal the casing in place.
[0004] Once the supporting structure is set in place, a slightly
smaller diameter drill bit may then be run in the newly cased hole
on the drill string, which has to be reassembled. Drilling may
re-commence once the previous depth is achieved by the drill
bit.
[0005] The above procedure is then repeated as necessary until the
total required depth of the bore is accomplished, and as will be
appreciated, the time taken to pull the drill bit and drill string
out of the hole, and to run new casing or liner into the hole will
increase after each drilling operation due to the increasing depth
of the bore.
[0006] Furthermore, as the bore is progressively drilled in the
manner described above, various readings must be taken in the bore
before the casing is cemented in place, such as depth, temperature,
pressure, formation characteristics and the like. Acquiring such
readings is generally termed "logging" or "open hole logging" and
is normally carried out with the drill bit removed from the
unsupported hole. Some logging operations, however, may be achieved
with the drill bit located in the hole, and even while drilling, by
utilising Logging While Drilling (LWD) tools or Measurement While
Drilling (MWD) tools, which can be elaborate and expensive.
[0007] It among aspects of embodiments of the present invention to
obviate, or at least mitigate one of the aforementioned
problems.
[0008] According to a first aspect of the present invention, there
is provided a method of forming a supported bore comprising the
steps of:
[0009] mounting a first drill bit on a first tubular member;
[0010] drilling a first bore to a first depth;
[0011] inserting a second drill bit mounted on a second tubular
member within the first tubular member; and
[0012] directing the second drill bit towards a wall portion of the
first tubular member and drilling through said wall portion and
drilling a second bore to a second depth.
[0013] According to a second aspect of the present invention, there
is provided a drilling assembly comprising a first drill bit
mounted on a first tubular member and a second drill bit mounted on
a second tubular member, wherein at least said first tubular member
includes a deflecting member mounted therein.
[0014] Preferably, the first tubular member is cemented or
otherwise fixed in the bore, before or after the second bore is
drilled.
[0015] Once the second bore is drilled to the required depth, the
second tubular member may then be cemented or otherwise fixed in
place within the second bore.
[0016] Preferably, the second drill bit is directed towards the
wall portion of the first tubular member by use of a deflecting
member mounted within the first tubular member.
[0017] Preferably also, the first drill bit is located on a
steerable tool before being mounted on the first tubular member in
order to provide the first drill bit and tubular member with
directional drilling capability.
[0018] Thus, a supported bore may be provided by initially drilling
a first bore using the first drill bit mounted on the first tubular
member, wherein the first bore may be deviated as required by use
of the steerable tool. Once the first bore has been drilled to the
required depth, which depth may be dictated by the requirement to
support the wall of the bore, a cement slurry or mixture is pumped
into the annulus formed between the first tubular member and the
bore wall to secure the first tubular member in the first bore. The
drill bit and steerable tool may also be cemented in place and
therefore become disposed in the bore.
[0019] To drill further, the second tubular member and drill bit
are run into the first tubular member until the second drill bit
reaches the level of the deflecting member, which forces or guides
the second drill bit towards the wall of the first tubular member,
through which an opening is drilled, allowing the second tubular
member and drill bit to exit the first tubular member and proceed
to drill a second bore. Thus, drilling through the wall of the
first tubular member avoids the requirement to drill through the
first drill bit, and steerable tool if present, to drill to the
second depth.
[0020] Once the second bore is drilled as required, the second
tubular member may then be cemented in place to support the bore
wall. The process may then be repeated until the required total
bore depth is achieved.
[0021] By cementing the drill bit supporting tubular members in
place to case or line the bores, the time normally associated with
providing a cased bore is greatly reduced as the requirement to
pull the drill string and drill bit out of the hole and then run in
a string of casing or a liner is eliminated.
[0022] Advantageously, the method according to the first aspect is
particularly adapted for use in producing a supported bore which
extends from surface level and intersects a subterranean
hydrocarbon bearing formation.
[0023] Conveniently, the supported bore may be a deviated bore or a
multilateral bore or the like.
[0024] The second drill bit may also be located on a steerable tool
in order to provide the second drill bit and tubular member with
directional drilling capability.
[0025] Preferably, the steerable tool is a mechanical device that
can be adjusted to effect changes in bore direction. The steerable
tool may take any appropriate form and may be, for example, a
directional drilling apparatus such as that described in
Applicant's UK Patent Application no. 0212553, the disclosure of
which is incorporated herein by reference.
[0026] As noted above, the deflecting member, in use, directs the
second drill bit towards the wall portion of the first tubular
member, through which a hole is drilled to allow a second bore to
be drilled. The deflecting member is preferably set at a chosen
angle with respect to the longitudinal axis of the first tubular
member. Preferably also, the deflecting member is fixed relative to
the first tubular member. The deflecting member may be set at an
angle of between 0.5 to 5 degrees with respect to the longitudinal
axis of the first tubular member, resulting, in use, in the second
drill bit being deflected from its initial path by a corresponding
angle.
[0027] Preferably, the deflecting member includes a hardened
surface to deflect the second drill bit towards the wall of the
first tubular member, and to prevent the member from being
destroyed by the drill bit.
[0028] Preferably also, the deflecting member defines at least one
fluid communicating aperture which allows the flow of fluids
through and past the deflecting member. Such fluids may be drilling
fluid or cement slurry or the like.
[0029] Conveniently, the deflecting member may be a whipstock or a
kick-off plate or the like.
[0030] Advantageously, the portion of the wall of the first tubular
member opposing the deflecting member is of a reduced hardness
relative to the remaining portion of the first tubular member. This
allows the second drill bit to more readily drill through the wall
of the first tubular member. The portion of the wall to be drilled
may, for example, be composed of a relatively soft metallic
material or a composite material or the like.
[0031] Preferably, the first tubular member is a tubing string or a
drill string comprising at least one, and preferably a plurality of
casing tubulars. Alternatively, the tubing or drill string may
comprise at least one liner tubular.
[0032] Conveniently, the second tubular member is a tubing string
or a drill string and preferably comprises a plurality of casing
tubulars and/or liner tubulars or the like. Alternatively, the
second tubular member may comprise a plurality of drilling tubulars
or drilling collars, or a combination thereof.
[0033] Advantageously, rotation of the drill bit to effect drilling
is provided by corresponding rotation of the tubular member upon
which it is mounted. Alternatively, rotation of the drill bit may
be achieved by use of a downhole drive unit, such as a positive
displacement mud motor, for example.
[0034] Advantageously, at least the first tubular member includes a
valve assembly for preventing fluids such as cement which are
located in the annulus from flowing or being displaced into the
tubular member. The valve assembly may be a collar having a
selectively closable fluid communicating throughbore. Preferably,
the valve assembly is a float collar and is located above the
deflecting member.
[0035] Preferably, the second tubular member also includes a valve
assembly, such as a float collar or the like.
[0036] Conveniently, the valve assembly defines a throughbore
allowing fluids such as cement or drilling fluid which are pumped
through the tubular members to pass therethrough. Preferably, the
through bore of the valve assembly may be selectively closed, by,
for example, a plug or dart provided from surface level.
Alternatively, the throughbore may be closed by a flapper valve or
a ball valve or the like.
[0037] Preferably, the first tubular member includes means for
determining at least one parameter of the bore.
[0038] Preferably also, the second tubular member includes a
deflecting member and means for determining at least one parameter
of the bore.
[0039] Conveniently, the means for determining at least one
parameter of the bore may include a data acquisition apparatus such
as a bore logging apparatus. Advantageously, the data acquisition
apparatus may perform data acquisition while the bore is being
drilled. Conveniently, a landing joint may be provided on a portion
of the corresponding tubular member in order to provide a means for
locating the data acquisition apparatus within the corresponding
tubular member, and also for allowing the acquisition apparatus to
be retrieved from within the tubular member.
[0040] In a preferred embodiment of the present invention, the
logging tool landing joint is located above the deflecting member
and is located in a fixed position relative thereto such that the
orientation of the deflecting member, and thus the deflection
angle, may be ascertained by, for example, the data acquisition
apparatus. Thus, the direction in which the second bore will
initially be drilled by the second drill bit can readily be
determined by knowing the orientation of the deflecting member.
[0041] Preferably, any data acquisition apparatus located within a
corresponding tubular member is retrieved before the tubular member
is cemented in place within the bore.
[0042] Thus, by providing a data acquisition apparatus of the type
described above which may acquire data while the bore is being
drilled, the requirement to pull the drill bit and corresponding
tubular member out of the hole to perform such data acquisition in
a separate operation is eliminated.
[0043] Conveniently, the first tubular member further includes
means for determining the orientation of the first drill bit. This
may be achieved by use of the data acquisition apparatus, for
example. Alternatively, the orientation of the first drill bit may
be achieved by use of a Measurement While Drilling (MWD) apparatus.
Alternatively further, the steerable tool upon which the first
drill bit is located may include means for directly or indirectly
determining the orientation of the first drill bit.
[0044] Preferably, means are provided for determining the
orientation of the second drill bit, which means may be included in
the second tubular member and may comprise MWD apparatus or Logging
While Drilling (LWD) apparatus or the like. Alternatively, where
the second drill bit is located on a steerable tool, the
orientation of the second drill bit may be directly or indirectly
determined by said steerable tool.
[0045] According to a third aspect of the present invention, there
is provided a method of forming a supported bore comprising the
steps of:
[0046] locating a first drill bit on a steerable tool and mounting
the steerable tool and first drill bit on a first tubular member,
said first tubular member including a deflecting member and means
for determining at least one parameter of the bore and the
orientation of the drill bit;
[0047] drilling a first bore to a first depth;
[0048] inserting a second drill bit mounted on a second tubular
member within the first tubular member; and
[0049] drilling through a wall portion of the first tubular member
at the location of the deflecting member and drilling a second bore
to a second depth.
[0050] According to a fourth aspect of the present invention, there
is provided a method of forming a supported bore, said method
comprising the steps of:
[0051] locating a first drill bit on a first expandable tubular
member having an upper portion of a first diameter and a lower
portion of a second, larger diameter;
[0052] drilling a bore with the drill bit mounted on the first
expandable tubular member;
[0053] pumping cement into an annulus formed between the expandable
tubular member and the wall of the bore; and
[0054] expanding the upper portion of the tubular member to a third
diameter, greater than the first diameter.
[0055] Preferably, the third diameter is substantially equal to the
second diameter.
[0056] According to a fifth aspect of the present invention, there
is provided a drilling assembly comprising a first drill bit
mounted on a first expandable tubular member, wherein said first
expandable tubular member includes an upper portion of a first
diameter and a lower portion of a second, larger diameter.
[0057] Advantageously, the volume of cement pumped into the annulus
between the tubular member and the bore wall is selected such that
the annulus is substantially filled with cement when the upper
portion of the expandable tubular member has been expanded.
[0058] Preferably, the upper portion of the tubular member is
expanded by use of an expansion mandrel forced through the tubular
member. Preferably, the mandrel is moved in an upwards direction to
expand the tubular member. Alternatively, the mandrel is moved in a
downwards direction through the tubular member.
[0059] Conveniently, the mandrel is substantially conical or
frusto-conical. It should be noted, however, that any other shape
of mandrel as would readily be selected by a person of skill in the
art may be used.
[0060] Preferably, the tubular member includes a valve member
defining a throughbore through which fluid may pass. Additionally,
the mandrel may define a fluid transmitting throughbore providing a
passage for fluid. Thus, fluid such as drilling fluid or cement may
be pumped into the tubular member, pass through the throughbores in
the mandrel and the valve member respectively, and proceed to flow
into the annulus between the bore wall and the tubular member.
[0061] Conveniently, the valve member is a collar such as a float
collar and assists in preventing fluid contained within the annulus
from flowing or being displaced into the tubular member.
[0062] Preferably, the mandrel is initially located within the
lower portion of the tubular member above the valve member.
[0063] Once the required volume of cement is located within the
annulus, the throughbore in the valve member may be closed by a
plug or dart provided from surface, or alternatively by a flapper
valve or a ball valve or the like. Thus a chamber may be formed
between the collar and the mandrel.
[0064] Preferably, the method further comprises the step of
pressurising the chamber formed between the mandrel and the valve
member, or otherwise creating a pressure differential across the
mandrel, such that the mandrel is forced upwards or downwards as
required through the tubular member to effect expansion due to a
pressure differential between the fluid above and below the
mandrel.
[0065] Preferably, by initially pressurising the chamber, the
throughbore in the mandrel is closed to maximise the above noted
pressure differential. The mandrel throughbore may be closed by use
of a one way pressure valve, for example, such as a flapper valve
or the like.
[0066] The chamber may be pressurised with a fluid provided from
surface, which fluid may be pumped through the mandrel and into the
chamber. Preferably, the mandrel comprises a pumping mechanism to
pump fluid into the chamber. Alternatively, a separate pumping unit
may be utilised to pump fluid into the chamber, which separate
pumping unit may be located adjacent the mandrel or alternatively
at surface level.
[0067] Alternatively, or additionally, the mandrel may be forced
through the tubular member by pulling from the surface. For
example, once the appropriate drill bit has reached the required
depth, a support member, such as a string of drill pipe or a
reelable support, may be fed down hole and coupled to the mandrel,
which support may be used to pull the mandrel upwards, to effect,
or assist in expanding the tubular member in which it is located.
Alternatively, or in addition, the support may be utilised to
supply pressurised fluid to create a pressure differential across
the mandrel, or in other embodiments may be utilised to push the
mandrel downwards to expand the tubular mandrel.
[0068] Advantageously, once the tubular member has been expanded as
required, the mandrel may be removed therefrom.
[0069] Preferably, the method further comprises the step of
inserting a second drill bit mounted on a second tubular member
within the first tubular member after said first tubular member has
been expanded and drilling through a wall portion of the first
tubular member and subsequently drilling a second bore.
[0070] Once the second bore is drilled to the required depth,
cement may be pumped into an annulus formed between the wall of the
second bore and the second tubular member.
[0071] Advantageously, the first expandable tubular member includes
a deflecting member, which deflecting member, in use, deflects or
guides the second drill bit towards a wall portion of the first
tubular member to be drilled. Preferably, the deflection member is
located below the valve member and the mandrel.
[0072] Preferably, the deflecting member is set at a chosen angle
with respect to the longitudinal axis of the first tubular member.
Preferably also, the deflecting member is fixed relative to the
first tubular member. The drilling member may be set at an angle of
between 0.5 to 5 degrees with respect to the longitudinal axis of
the first tubular member, resulting in the second drill bit being
deflected by a corresponding angle.
[0073] Advantageously, the portion of the wall of the first tubular
member opposing the deflecting member is of a reduced hardness
relative to the remaining portion of the first tubular member. This
allows the second drill bit to more readily drill through the wall
of the first tubular member. The portion of the wall to be drilled
may, for example, be composed of a relatively soft metal material
or a composite material or the like.
[0074] Preferably, the deflecting member includes a hardened
surface to deflect the second drill bit towards the wall of the
first tubular member, and to prevent the member from being
destroyed by the drill bit.
[0075] Preferably also, the deflecting member defines at least one
fluid communicating aperture which allows the flow of fluids
through and past the deflecting member. Such fluids may be drilling
fluid or a cement slurry or the like.
[0076] Conveniently, the deflecting member may be a whipstock or a
kick-off plate or the like.
[0077] In one embodiment of the present invention, the second
tubular member may be expandable and a portion thereof may be
expanded to a larger diameter once the second bore has been drilled
to the required depth. The second tubular member may be expanded
before cement is pumped into the annulus between the second bore
wall and the second tubular member, or may preferably be expanded
after cement is pumped into the annulus.
[0078] Preferably, the first tubular member is a tubing string or a
drill string comprising at least one, and preferably a plurality of
casing tubulars. Alternatively, the tubing or drill string may
comprise at least one liner tubular.
[0079] Conveniently, the second tubular member is a tubing string
or a drill string and preferably comprises a plurality of casing
tubulars and/or liner tubulars or the like. Alternatively, the
second tubular member may comprise a plurality of drilling tubulars
or drilling collars, or a combination thereof.
[0080] Preferably, the first drill bit is located on a steerable
tool such that the first drill bit and the first tubular member are
provided with directional drilling capability.
[0081] Similarly, the second drill bit may be located on a
steerable tool.
[0082] In a preferred embodiment, the first tubular member includes
means for determining at least one parameter of the bore.
Conveniently, the means for determining at least one parameter of
the bore may include a data acquisition apparatus such as bore
logging apparatus. Advantageously, the data acquisition apparatus
may perform data acquisition while the bore is being drilled.
Conveniently, a landing joint may be provided on a portion of the
corresponding tubular member in order to provide a means for
locating the data acquisition apparatus within the corresponding
tubular member, and also for allowing the acquisition apparatus to
be retrieved from within the tubular member.
[0083] In a preferred embodiment of the present invention, the
logging tool landing joint is located above the deflecting member
and is located in a fixed position relative thereto such that the
orientation of the deflecting member, and thus the deflection
angle, may be ascertained by, for example, the data acquisition
apparatus. Thus, the direction in which the second bore will be
drilled by the second drill bit can readily be determined.
[0084] Preferably, any data acquisition apparatus located within a
corresponding tubular member is retrieved before the tubular member
is cemented in place within the bore.
[0085] Conveniently, the first tubular member further includes
means for determining the orientation of the first drill bit. This
may be achieved by use of the data acquisition apparatus, for
example. Alternatively, the orientation of the first drill bit may
be achieved by use of a Measurement While Drilling (MWD) apparatus.
Alternatively further, the steerable tool upon which the first
drill bit is located may include means for directly or indirectly
determining the orientation of the first drill bit.
[0086] Preferably, means are provided for determining the
orientation of the second drill bit, which means may be included in
the second tubular member and may comprise MWD apparatus or Logging
While Drilling (LWD) apparatus or the like. Alternatively, where
the second drill bit is located on a steerable tool, the
orientation of the second drill bit may be directly or indirectly
determined by said steerable tool.
[0087] Advantageously, rotation of the drill bit to effect drilling
is provided by corresponding rotation of the tubular member upon
which it is mounted. Alternatively, rotation of the drill bit may
be achieved by use of a downhole drive unit, such as a positive
displacement mud motor, for example.
[0088] According to a sixth aspect of the present invention, there
is provided a method of forming a supported bore comprising the
steps of:
[0089] locating a first drill bit on a steerable tool and mounting
the steerable tool and first drill bit on a first expandable
tubular member, said first expandable tubular member including a
deflecting member and means for determining at least one parameter
of the bore and the orientation of the drill bit;
[0090] drilling a first bore to a first depth;
[0091] pumping cement into an annulus formed between the first
tubular member and the wall of the first bore;
[0092] expanding a portion of the first expandable tubular member
to a larger diameter;
[0093] inserting a second drill bit mounted on a second tubular
member within the first tubular member;
[0094] drilling through a wall portion of the first tubular member
at the location of the deflecting member and drilling a second bore
to a second depth; and
[0095] cementing the second tubular member in place within the
second bore.
[0096] These and other aspects of the present invention will now be
described, by way of example only, with reference to the
accompanying drawings, in which:
[0097] FIGS. 1 to 3 are diagrammatic cross-sectional views of a
drilling assembly for use in forming a supported bore in accordance
with an embodiment of an aspect of the present invention; and
[0098] FIGS. 4 to 7 are diagrammatic cross-sectional views of a
drilling assembly for use is forming a supported bore in accordance
with an embodiment of an alternative aspect of the present
invention.
[0099] Reference is first made to FIG. 1 in which there is shown a
cross-sectional view of a drilling assembly 10 for use in forming a
well bore 12 in accordance with one embodiment of an aspect of the
present invention. The drilling assembly 10 includes a drill bit 14
mounted on a tubular member 16 via a steerable tool 18. In the
embodiment shown the tubular member 16 is a string of casing
tubulars commonly used in subterranean well bores, which casing
string extends from surface and provides rotation and weight to the
drill bit 14. The steerable tool 18 is a mechanical device that can
be adjusted to effect changes in bore direction; that is, the
steerable tool 18 provides the drilling apparatus 10 with
directional drilling capability.
[0100] The drilling apparatus further includes a deflecting member
20 which defines a fluid communicating aperture 22 which allows the
flow of fluids therethrough. Additionally, a float collar 24 is
also provided, located above the deflecting member 20, which float
collar also defines a fluid communicating aperture 26. The
apertures 22 and 26 allow the passage of fluids such as a drilling
mud or a cement slurry or the like. Furthermore, the drilling
assembly 10 further includes a logging tool landing joint 28
located above the float collar 24 and the deflecting member 20. The
function of the deflecting member 20, float collar 24 and landing
joint 28 will become apparent from the subsequent description.
[0101] In use, the drilling assembly 10 drills a first bore 12 to a
first depth, wherein the steerable tool 18 is used to control the
direction of the bore 12. While drilling, a data acquisition
apparatus (not shown) or logging apparatus is positioned in the
tubular member in the region of the logging tool landing joint 28,
which landing joint 28 provides a means for locating the data
acquisition apparatus within the tubular member 16, and also for
allowing the acquisition apparatus to be retrieved from within the
tubular member 16. The data acquisition apparatus may be used to
record data such as bore depth, temperature, pressure and formation
characteristics and the like.
[0102] Once the first depth is achieved, the data acquisition
apparatus is retrieved from the tubular member 16, and cement 34 is
pumped through the tubular member, through apertures 22, 26, and
into the annulus 30 formed between the bore wall 32 and the tubular
member 16, as shown in FIG. 2. Once the required volume of cement
34 has been pumped into the annulus 30, a dart 36 is provided from
surface level which closes the aperture 26. Thus, the float collar
24 prevents cement from being displaced back into the tubular
member 16. As shown in FIG. 2, the drill bit 14 and steerable tool
18 also become cemented in place and therefore remain disposed in
the bore 12. By cementing the tubular member 16 in place a
supported bore may be provided without the requirement of pulling
the drill bit and associated drilling string out of the hole and
then running in and cementing in place a separate casing or liner
string to support and seal the bore.
[0103] To drill further, a second, slightly smaller diameter drill
bit 38 mounted on a second tubular member 40 is run into the
tubular member 16, as shown in FIG. 3 of the drawings. The second
drill bit 38 is rotated by the second tubular member 40 from
surface. The second drill bit 38 initially drills through the float
collar 34 and underlying cement until reaching the level of the
deflecting member 20 which directs the second drill bit towards a
wall portion 42 of tubular member 16, through which wall portion 42
a hole is drilled to allow the second drill bit 38 and tubular
member 40 to proceed to drill a second bore to a second depth.
[0104] The deflecting member 20 is set at a chosen angle with
respect to the longitudinal axis of tubular member 16. It should be
noted that the angle of inclination of the deflecting member 20 is
exaggerated in the drawings for illustrative purposes and that the
member 20 is likely to be set at an angle of between 0.5 and 5
degrees. The deflecting member 20 includes a hardened surface to
deflect the second drill bit 38 towards wall portion 42 and to
prevent the member 20 from being destroyed by the drill bit 38.
[0105] The deflecting member 20 is located in a fixed position
relative to the logging tool landing joint 28 (FIG. 1) such that
the orientation of the deflecting member 20, and thus the
deflection angle, may be ascertained by the data acquisition
apparatus when in place. Thus, the direction in which the second
bore will initially be drilled can readily be determined by knowing
the orientation of the deflecting member 20.
[0106] In the embodiment shown, the wall portion 42 to be drilled
by the drill bit 38 is of a reduced hardness relative to the
remaining portion of tubular member 16 to allow the drill bit 38 to
more readily drill through the wall of the tubular member 16. The
wall portion 42 may be composed of a relatively soft metallic
material or a composite material or the like.
[0107] Once the second bore has been drilled to a second depth, the
second drill bit 38 and tubular member 40 are cemented in place in
a similar fashion to that described with reference to FIG. 2 in
order to support and seal the second bore. Additionally, the second
tubular member 40 may also include a deflecting member such that a
further bore may be drilled from within the second tubular member
40.
[0108] As shown in FIG. 3, the second drill bit 38 is mounted on
the second tubular member 40 via a steerable tool 44 to provide the
second drill bit 38 with directional drilling capability.
[0109] Reference is now made to FIG. 4 in which there is shown a
diagrammatic cross-sectional view of a drilling assembly 100 for
use in forming a well bore 102 in accordance with an embodiment of
another aspect of the present invention. The drilling assembly 100
comprises a drill bit 104 mounted on an expandable tubular member
106 via a steerable tool 108. The steerable tool 108 is a
mechanical device that can be adjusted to effect changes in bore
direction; that is, the steerable tool 108 provides the drilling
apparatus 100 with directional drilling capability.
[0110] The tubular member 106 is a string of casing tubulars and
includes an upper portion 110 of a first diameter and a lower
portion 112 of a second larger diameter.
[0111] The drilling apparatus 100 further includes a deflecting
member 114 located within the lower portion 112, which deflecting
member 114 defines a fluid communicating aperture 116 which allows
the flow of fluids therethrough. Additionally, a float collar 118
is also provided within the lower portion, above the deflecting
member 114, which float collar also defines a fluid communicating
aperture 120. Furthermore, the drilling assembly 100 includes a
logging tool landing joint 122 located in the upper portion 110 of
the tubular member 106 above the float collar 118 and the
deflecting member 114. The function of the deflecting member 114,
float collar 118 and landing joint 122 are similar to those
described with reference to the embodiment shown in FIGS. 1 to 3,
as will become apparent from the subsequent description.
[0112] The drilling assembly 100 also includes an expansion mandrel
124 located in a transition region between the upper and lower
portions 110, 112. As shown in FIG. 4, the expansion mandrel 124
defines a fluid communicating throughbore 126 allowing for the
passage of fluids such as drilling mud or cement or the like.
[0113] In use, the drilling assembly 100 is utilised to drill a
bore 102 to the required depth and at the required orientation by
employment of the steerable tool 108. While drilling, a data
acquisition apparatus (not shown) is located in the upper portion
110 of the tubular member 106 at the location of the logging tool
landing joint 122 to record well bore data such as temperature and
pressure and the like. Additionally, the data acquisition apparatus
may assist in determining the orientation of the drill bit 104.
[0114] Once the required depth of the bore is achieved, the data
acquisition apparatus is retrieved from the tubular member 106 and
a cement slurry 130 is pumped into the tubular member 106, through
apertures 116, 120 and throughbore 126, and into an annulus 132
formed between the bore wall 134 and the tubular member 106, as
shown in FIG. 5. Once the required volume of cement 130 has been
pumped into the annulus 132, a dart 136 is provided from surface
level which passes through the throughbore 126 in the expansion
mandrel 124 and closes the aperture 120 in the float collar 118,
shown in FIG. 6. Thus, the float collar 118 prevents cement 130
from being displaced back into the tubular member 106. As described
above with reference to FIG. 2, the drill bit 104 and steerable
tool 108 also become cemented in place and therefore remain
disposed in the bore 102.
[0115] By closing aperture 120 in the float collar 118, a chamber
138 is formed between the collar 118 and the mandrel 124. Once the
dart 136 is in place, a fluid is pumped into the chamber 138
through the mandrel 124 to pressurise the chamber 138 in order to
force the mandrel 124 upwards through the tubular member 106 to
expand the upper portion 110, as shown in FIG. 7, before the cement
130 has cured. By initially pressurising the chamber 138 a flapper
valve 140 closes the throughbore 126 in the mandrel to maximise the
pressure differential between the fluid above and below the mandrel
124.
[0116] The chamber 138 is pressurised by fluid provided through a
tubular member 141 which is run in from surface to engage a
suitable profile on the mandrel 124, which fluid is pumped through
a further throughbore 142 in the mandrel 124. The tubular member
141 may take any appropriate form, and may be a string of drill
pipe, a reelable support, such as coil tubing, or a control line.
When a heavier tubular member 141 is utilised, such as a drill pipe
string, the member 141 may be utilised to pull the mandrel 124
upwardly through the tubular member 106 to assist in expansion of
the upper portion 110.
[0117] Once the upper portion 110 is fully expanded, the mandrel
124 is removed from the tubular member 106 and a structure similar
to that shown in FIG. 2 is produced. Further drilling may then be
achieved in a similar manner to that described with reference to
FIG. 3, wherein the deflecting member 114 deflects a further drill
bit towards the wall of the tubular member 106 to drill through
said wall and proceed to drill a further bore.
[0118] It should be obvious to a person of skill in the art that
the above described embodiments are merely exemplary of aspects of
the invention and that various modifications may be made thereto
without departing from the scope of the present invention. For
example, the drill bit may be directly mounted to the corresponding
tubular member and the drill bit may be rotated by downhole drive
means such as a positive displacement mud motor or the like.
Additionally, the second tubular member 40 shown in FIG. 3 may be a
recoverable drill string.
[0119] The embodiment shown in FIGS. 1 to 3 may be used in
combination with that shown in FIGS. 4 to 7, wherein a first
supported bore is provided using the drilling assembly 10 (FIG. 1),
and the drilling assembly 100 (FIG. 4) is run into the first
supported bore to form a second supported bore, wherein the
diameter of the second supported bore is maximised by expansion of
tubular member 106.
[0120] The tubular member 106 (FIG. 4) may be expanded before
cement is pumped into the annulus.
[0121] In another embodiment, the tubular member 141 may be adapted
to cooperate with the aperture 126 and be utilised to deliver the
cement 130 and the dart 136 from surface. In this case the flapper
valve 140 and the additional throughbore 142 may be omitted.
* * * * *