U.S. patent application number 12/095334 was filed with the patent office on 2009-10-29 for method and apparatus for installing deflecting conductor pipe.
This patent application is currently assigned to FRANK'S INTERNATIONAL, INC.. Invention is credited to Louie Horvath, Charles Michael Webre.
Application Number | 20090266559 12/095334 |
Document ID | / |
Family ID | 37814598 |
Filed Date | 2009-10-29 |
United States Patent
Application |
20090266559 |
Kind Code |
A1 |
Horvath; Louie ; et
al. |
October 29, 2009 |
METHOD AND APPARATUS FOR INSTALLING DEFLECTING CONDUCTOR PIPE
Abstract
Delivering an additional subterranean conduit (124) along a
deflected path relative to an existing conduit (120) is used for
installing additional conductor pipes (124) from an existing
production platform (50). A deflecting member in the form of a shoe
(114, 115; 214) has a coupling means in the form of a screwthread
for coupling to a lowermost end of an additional conduit (124). The
shoe (114, 115; 214) is arranged to deliver the additional conduit
(124) along the deflected path when the shoe (114, 115; 214)
contacts whipstock (126; 226) which has been installed on top of an
existing conductor pipe (120). The method can include running in
the whipstock (126; 226) as a first step on an elongate member such
as a drill string (94) and then withdrawing the drill string (94)
and then running in the additional conduit (124). The outer
diameter of the additional conduit (124) is maximised as it passes
through conductor guides (52) attached to the production platform
(50).
Inventors: |
Horvath; Louie; ( Norfolk,
GB) ; Webre; Charles Michael; (Lafayette,
LA) |
Correspondence
Address: |
OSHA LIANG LLP - Frank's International
TWO HOUSTON CENTER, 909 FANNIN STREET, SUITE 3500
Houston
TX
77010
US
|
Assignee: |
FRANK'S INTERNATIONAL, INC.
Houston
TX
|
Family ID: |
37814598 |
Appl. No.: |
12/095334 |
Filed: |
December 1, 2006 |
PCT Filed: |
December 1, 2006 |
PCT NO: |
PCT/GB2006/004497 |
371 Date: |
August 27, 2008 |
Current U.S.
Class: |
166/382 ;
166/117.6 |
Current CPC
Class: |
E21B 7/061 20130101;
E21B 7/043 20130101 |
Class at
Publication: |
166/382 ;
166/117.6 |
International
Class: |
E21B 23/12 20060101
E21B023/12; E21B 23/00 20060101 E21B023/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 3, 2005 |
GB |
0524750.7 |
Oct 11, 2006 |
GB |
0620101.6 |
Claims
1-39. (canceled)
40. An apparatus to deliver a secondary conduit along a path
deflected relative to a pre-existing conduit, the apparatus
comprising: a whipstock delivered to a deflection point above an
upper end of the preexisting conduit; a coupling disposed at a
distal end of the whipstock, wherein the coupling is configured to
secure the whipstock to the pre-existing conduit at a selected
orientation; wherein the selected orientation aims a trough of the
whipstock in a desired trajectory; and a deflecting shoe connected
to a distal end of the secondary conduit, wherein the deflecting
shoe is configured to engage the trough of the whipstock and
deflect the secondary conduit at the desired trajectory.
41. The apparatus of claim 40, wherein the deflecting shoe
comprises a drillable material.
42. The apparatus of claim 40, wherein the deflecting shoe
comprises holes extending therethrough, wherein the holes permit
the passage of materials between an outer surface of the deflecting
shoe and a bore of the secondary conduit.
43. The apparatus of claim 40, wherein the deflecting shoe
comprises a substantially conical outer surface.
44. The apparatus of claim 40, wherein an inner diameter of the
whipstock is less than an outer diameter of the secondary
conduit.
45. The apparatus of claim 40, wherein the deflecting shoe
comprises a head portion and a collar portion, wherein the head
portion is larger in diameter than the collar portion.
46. The apparatus of claim 45, wherein a neck portion is provided
between the head portion and the collar portion, wherein the neck
portion comprises an outwardly projecting shoulder extending in a
radial direction with respect to a longitudinal axis of the
deflecting shoe.
47. The apparatus of claim 45, further comprising a first coupler
on the outer surface of the collar portion, the coupler configured
to couple to a corresponding second coupler of the distal end of
the secondary conduit.
48. The apparatus of claim 47, wherein the first and the second
couplers comprise corresponding screw threads.
49. A method to deliver a secondary conduit in a path deflected
from a pre-existing conduit, the method comprising: providing a
deflecting shoe to a lower end of the secondary conduit; providing
a whipstock to an upper end of the pre-existing conduit; delivering
the lower end of the additional conduit to the whipstock through at
least one guide member; securing the whipstock to the preexisting
conduit; urging the additional conduit in a desired trajectory with
a trough of the whipstock; and deflecting the additional conduit
away from the pre-existing conduit in the desired trajectory.
50. The method of claim 49, further comprising delivering the
whipstock to the upper end of the pre-existing conduit at the end
of a delivery conduit.
51. The method of claim 49, further comprising delivering the
whipstock to the upper end of the pre-existing conduit upon the
lower end of the secondary conduit.
52. The method of claim 51, further comprising delivering the
whipstock and urging the additional conduit in the desired
trajectory in a single trip.
53. The method of claim 51, further comprising shearing the
whipstock from the secondary conduit when secured to the
pre-existing conduit.
53. The method of claim 49, further comprising coupling the
whipstock about an outer diameter of the preexisting conduit.
54. The method of claim 49, further comprising coupling the
whipstock within an inner diameter of the pre-existing conduit.
55. The method of claim 49, further comprising deploying the
whipstock to the pre-existing conduit through the at least one
guide member.
56. The method of claim 55, further comprising expanding a diameter
of the trough of the whipstock with a larger diameter of the
secondary conduit.
57. The method of claim 49, further comprising longitudinally
loading the secondary conduit to deflect it away from the
pre-existing conduit in the desired trajectory.
Description
[0001] The present invention provides a method and apparatus for
delivering an additional subterranean conduit along a deflected
path relative to an existing conduit. In particular, the invention
relates to the installation of a subterranean conductor pipe along
a deflected path relative to an existing conductor pipe that led to
a hydrocarbon reservoir.
[0002] It is usual in the offshore hydrocarbon recovery and
production industry to drill a number of wellbores and to use a
respective number of conductor pipes leading downwards from a
production platform through supporting conductor guides, wherein
the conductor pipes transfer the produced hydrocarbons back to the
production platform. Such wells are very expensive to drill and
such production platforms are very expensive to maintain.
Inevitably, each drilled well has a finite life and it is
commercially and environmentally advantageous to be able to drill
more wells from the existing production platform in order to tap
previously undrilled reservoirs in the reachable vicinity of the
platform. Accordingly, there is a need to be able to install
additional conductor pipes from the existing production platform
and conventionally this is achieved by removing an upper portion of
an existing but dry conductor pipe and installing a new or
additional conductor pipe along a deflected path from that of the
existing but dry conductor. This is known as lost well slot.
[0003] There are two known methods for installing conductor pipe
along a deflected path from an offshore platform: below the mud
line (subsea well slot recovery) and at or above the seabed (seabed
well slot recovery). These methods are shown schematically in FIGS.
1-4.
[0004] FIGS. 1-3 show the below mud-line method. This method is
typically used when there is a conductor guide 22 close to the
seabed, typically 2 to 8 feet (0.61 to 2.44 m) above the
seabed.
[0005] The conventional method shown in FIG. 1 involves cutting an
existing pipe 20 leading from a platform (not shown in FIG. 1) to a
subterranean reservoir (not shown) that previously contained
hydrocarbons. Firstly, the uppermost section (which may be in the
region of 50-80 feet or so) of the existing conductor pipe is
reamed out in order to create a large diameter hole 32 in the mud
extending downwardly from the mouth of the borehole, and to leave
the rest of the conductor pipe 20 in situ. In order to prevent the
large diameter hole 32 from collapsing, a high viscosity mud can be
pumped therein. An additional conductor pipe 24, with a whipstock
26 shear bolted thereto, is then run through the conductor guide 22
and it is this stage that is shown in FIG. 1. The lower end of the
whipstock 26 is provided with a landing ring 28 having a diameter
greater than that of the existing pipe 20 such that when a spear 30
is landed in the bore of the existing pipe 20, the landing ring 28
abuts the upper end of the pipe 20 to ensure that the whipstock 26
is seated thereon. The landing ring 28 also bears the shock when
the additional conductor pipe 24 is sheared off the whipstock
26.
[0006] FIG. 2 shows an alternative method (known as overshot
whipstock) of coupling the whipstock 26 to the upper end of the
existing pipe 20, whereby the lower end of the whipstock 26 is
provided with a large diameter portion 36, known in the art as an
overshot. The inner diameter of the overshot 36 is greater than the
outer diameter of the existing pipe 20 such that the overshot 36
accommodates the end of the existing pipe 20 therein.
[0007] Once the whipstock 26 of FIGS. 1 and 2 is respectively
landed within or over the existing pipe 20, a force is applied to
the new conductor pipe 24, typically by dropping the weight of the
pipe 24, to shear the shear bolts coupling the new pipe 24 and the
whipstock 26. Thus the new pipe 24 is deflected by the whipstock 26
and can be hammer driven from the platform to the required
penetration depth along a deflected path 38, as shown in FIG.
3.
[0008] The method of FIGS. 1 to 3 is discussed in more detail in
U.S. Pat. No. 4,733,732 to Inventor Samuel C. Lynch (Assigned to
Atlantic Richfield Company--ARCO) and the paper titled "Submudline
Drivepipe Whipstock: A Cost Effective Method of Reclaiming Platform
Slots" by S. M. Provance of ARCO Oil & Gas Co. presented at the
1986 IADC/SPE Drilling Conference held in Dallas, Tex. from 10 to
12 Feb. 1986 (publication ref IADC/SPE 14731).
[0009] FIG. 4 shows a diagrammatic representation of the above
seabed method. This method is utilised if there is no conductor
guide 52 at least 60 feet (18.3 metres) above the seabed 34. The
existing pipe 20 is cut at around 5 to 10 feet (1.5 to 3 metres)
above the seabed 34. The new conductor pipe 24 is made up as
previously described and is shear bolted to the whipstock 26. The
new conductor 24 and coupled whipstock 26 is guided down through
one or more conductor guides 52 incorporated in a platform
structure 50. A force is then applied to the new conductor pipe 24
to shear the bolts coupling the conductor pipe 24 and the whipstock
26 and the whipstock 26 deflects the new conductor pipe 24 along a
deflected path. The new conductor pipe 24 is then hammer driven
from the platform 50 to a predetermined penetration depth.
[0010] The main drawback associated with both the below mud-line
and above seabed methods is that it is only possible to install new
conductor pipe 24 that is smaller in diameter than the inner
diameter of the conductor pipe guides 22, 52. For example, if the
inner diameter of the conductor guides 22, 52 is 32 inches (81.3
cm), a typical outer diameter for the new conductor pipe would be
30 inches (76.2 cm). This is due to the fact that the whipstock 26
has a wall thickness at the point that it is shear bolted to the
conductor pipe 24 (as an example, the wall thickness could be in
the region of 3/4 inch (1.9 cm)). Therefore, because the
combination of the outer diameter of the conductor pipe 24 and the
whipstock 26 must be smaller than the inner diameter of the
conductor guides, the outer diameter of the conductor pipe 24 must
be substantially smaller than the inner diameter of the conductor
guides. By way of example only, if the outer diameter of the
conductor pipe 24 is 30 inches (76.2 cm) and the wall thickness of
the whipstock is 3/4 inch (1.9 cm), the total diameter of the
assembly is 31.5 inches (80 cm), which is the maximum outer
diameter possible for the assembly, while just enabling the
assembly to run through the conductor guides 22, 52.
[0011] Furthermore, it is not generally possible to install a new
conductor pipe using conventional techniques where existing
conductor pipes have been cemented below the seabed, since the
cement bonds the existing conductor pipe to its surroundings and
therefore prevents the existing conductor pipe from being extracted
from the ground, since the existing conductor with cement bonded
thereto would not fit through the pipe guides.
[0012] According to a first aspect of the invention, there is
provided a method of delivering an additional subterranean conduit
along a deflected path from an existing conduit, comprising the
steps of:
[0013] (a) providing a deflecting member at a lower end of the
additional conduit;
[0014] (b) installing a path diverting means at or towards an upper
end of an existing conduit;
[0015] (c) delivering the lower end of the additional conduit
towards the upper end of the existing conduit; and
[0016] (d) deflecting the lower end of the additional conduit
utilizing the path diverting means to thereby urge the additional
conduit along a deflected path relative to the existing
conduit.
[0017] Preferably, the method further comprises step (e) of
installing the additional conduit along the deflected path.
[0018] Step b) may be carried out simultaneously with step c).
Alternatively, step b) may be carried out prior to step c).
[0019] According to the first aspect of the invention, there is
also provided apparatus for delivering an additional subterranean
conduit along a deflected path relative to an existing conduit, the
apparatus comprising a deflecting member having a coupling means
for coupling the deflecting member to a lowermost end of the
additional conduit in use, wherein, in use, the deflecting member
is arranged to deliver the additional conduit along the deflected
path when the deflecting member contacts a predetermined
structure.
[0020] The deflecting member can comprise a surface angled with
respect to the longitudinal axis of the existing conduit. The
angled surface can be planar. For example, the surface can be
angled in the region of between 20.degree. to 70.degree., and more
preferably can be angled in the region of between 30.degree. to
60.degree., and most preferably can be angled at 45.degree. with
respect to the longitudinal axis of the additional conduit although
other angles, as conditions may warrant, will suffice.
[0021] Alternatively, the deflecting member can have an outer
surface comprising an aerodynamically efficient shape and may be
somewhat or substantially conical. The outer surface of the
deflecting member is preferably in the form of a paraboloid or
bullet shaped.
[0022] A portion of the deflecting member adjacent the lower end of
the additional conduit can have a larger outer diameter than that
of the conduit. The outer diameter of the portion of the deflecting
member can be between 0.2 and 0.5 inches (0.51 and 1.27 cm) larger
than that of the conduit. This provides the advantage that there is
a minimised risk of the joint between the deflecting member and the
additional conduit getting stuck on the pre-determined structure
during downward movement of the deflecting member and additional
conduit.
[0023] The deflecting member can be formed from a drillable
material and may be provided in the form of an aluminium or hard
plastics or composite material shoe.
[0024] The deflecting member can be provided with one or more holes
extending therethrough.
[0025] Preferably the deflecting member comprises a head portion
and a collar portion wherein the collar portion is preferably
generally tubular in cross section and more preferably is smaller
in outer diameter than the head portion. Typically, a neck portion
is provided between the head portion and the collar portion wherein
the neck portion comprises an outwardly projecting shoulder, which
preferably extends in a perpendicular direction with respect to the
longitudinal axis of the deflecting member. Typically, a coupling
means is provided on the outer surface of the neck portion which is
adapted to couple to a coupling means provided on the internal
surface of the lower end of the additional conduit. Typically, the
said coupling means are corresponding screw threads.
[0026] The predetermined structure can comprise a path diverting
means arranged for insertion in the upper end of the existing
conduit. The path diverting means can comprise a whipstock.
[0027] The inner diameter of the path diverting means can be less
than the outer diameter of the additional conduit.
[0028] The coupling means can be adapted to prevent rotation
between the additional conduit and the deflecting member.
[0029] According to a second aspect of the present invention, there
is provided a method of installing an additional subterranean
conduit, comprising the steps of:
[0030] (a) installing a path diverting means at or towards an upper
end of an existing conduit using a deployment means;
[0031] (b) removing the deployment means following installation of
the path diverting means;
[0032] (c) delivering a lower end of the additional conduit towards
the upper end of the existing conduit;
[0033] (d) deflecting the lower end of the additional conduit using
the path diverting means to thereby urge the additional conduit
along a deflected path relative to the existing conduit; and
[0034] (e) installing the additional conduit along the deflected
path.
[0035] The method according to the second aspect has the advantage
that the outer diameter of the additional conduit is maximised
because it is run in separately from the path diverting means.
[0036] The method typically further relates to delivering an
additional subterranean conduit along a deflected path from an
existing conduit.
[0037] The method can include removing a portion of the existing
conduit prior to commencing step (a).
[0038] Prior to step (c), the method may further comprise providing
a deflecting member at the lower end of the additional conduit.
Preferably, the deflecting member is coupled to the lower end of
the additional conduit.
[0039] The deployment means may comprise an elongate member and,
prior to step (a), the method can further comprise coupling the
path diverting means to an elongate member via a connection means
which may preferably comprise a threaded connection means.
[0040] Step (a) of the method can further comprise applying a
longitudinal force to the elongate member thereby securing the path
diverting means in the upper end of the existing conduit.
[0041] Following step (a), the method preferably further comprises
decoupling the elongate member and the path diverting means and
withdrawing the elongate member.
[0042] The method can further comprise installing the path
diverting means through the throughbore of one or more guide
members. The method can include maximising the outer diameter of
the path diverting means while enabling it to fit through the
throughbore of the one or more guide members.
[0043] The method may further include providing the deflecting
member with deflecting surfaces and shaping the deflecting surfaces
and thereby urging the conduit on the deflected path.
[0044] The method may further include providing the deflecting
member with an angled end member.
[0045] The method may include angling at least a portion of the
deflecting member in the region of between 20.degree. to
70.degree., and more preferably in the region of between 30.degree.
to 60.degree., and most preferably at 45.degree. relative to a
longitudinal axis of conduit, although other angles, as conditions
may warrant, will suffice. Alternatively, the method can include
shaping the deflecting member in an aerodynamic manner such as in
the shape of a paraboloid and thereby splaying at least a portion
of the path diverting means during step (d).
[0046] According to another aspect of the present invention, there
is provided a method of installing an additional subterranean
conduit, comprising the steps of:
[0047] (a) providing the additional conduit with a deflecting
member coupled to an end thereof;
[0048] (b) detachably coupling an end of a path diverting means to
a portion of the additional conduit;
[0049] (c) installing the path diverting means and coupled
additional conduit at or towards an end of an existing conduit;
[0050] (d) applying a longitudinal force to the additional conduit
and thereby decoupling the additional conduit from the path
diverting means;
[0051] (e) deflecting the additional conduit to thereby urge the
additional conduit along a deflected path relative to the existing
conduit; and
[0052] (f) installing the additional conduit along the deflected
path.
[0053] The method typically further relates to delivering an
additional subterranean conduit along a deflected path from an
existing conduit.
[0054] The method preferably further includes orienting the path
diverting means during installation with respect to the existing
conduit such that the deflected path diverges away from the
existing conduit and structures associated therewith.
[0055] In one preferred embodiment, the method preferably further
includes deflecting the additional conduit around a structure which
may be a pipe guide brace coupled to the existing conduit and the
method can further include shaping the deflecting member such that
it comprises a planar surface angled with respect to the
longitudinal axis of the additional conduit.
[0056] However, in an alternative embodiment, the method can
include shaping the deflecting member such that it comprises a
somewhat or substantially conical outer surface such as in the
shape of a paraboloid.
[0057] Any feature of any aspect of any invention described herein
may be combined with any feature of any aspect of any other
invention described herein mutatis mutandis.
[0058] Embodiments of the invention will now be described with
reference to and as shown in the accompanying drawings, in
which:
[0059] FIGS. 5 and 6 are side and front views respectively of a
whipstock used in one embodiment according to the present
invention;
[0060] FIGS. 7 and 8 are side and front views of a conductor pipe
having a deflecting end member and part of the whipstock shown in
FIGS. 5 and 6 although the spear 130 is not shown in FIGS. 7 and
8,
[0061] FIG. 9 is a side view of a conductor pipe deflected along a
deflected path;
[0062] FIGS. 10 and 11 are side and front views of a whipstock and
an additional conductor pipe with an end member used in a second
embodiment in accordance with the present invention;
[0063] FIG. 12 shows the additional conductor pipe of FIGS. 10 and
11 along a deflected path;
[0064] FIGS. 13 and 14 are side and perspective views respectively
of the end member of FIGS. 10 and 11; and
[0065] FIGS. 15 and 16 are side and perspective views of the end
member of FIGS. 7 and 8.
[0066] A whipstock is shown generally at 126 in FIG. 5. The
whipstock 126 has a trough 102 defined by the outer edges
converging towards the lower end of the whipstock 126 and providing
a gently curved surface 104 therebetween. The surface 104 is
provided with an elongate hole 106 allowing an elongate member 94
such as a relatively slim drill string 94 to be accommodated
therethrough. Within the whipstock 126, a connector 108 is provided
with an open end 110 having an internal thread and is in the form
of a 41/2 inch drill pipe box connector 110. The box connector 110
engages with thread 96 provided on a pin connection located at the
lower end of the drill string 94.
[0067] Alternatively, the box connector 110 can be replaced by any
other form of suitable connection means if a different type of
connector is required, such as a "J"-latch, an annular groove with
associated locking ring arrangement, etc. etc.
[0068] The whipstock 126 has a landing ring 128 and a spear 130.
The outer diameter of the spear 130 is less than the inner diameter
of an existing conductor pipe 120 in which the whipstock 126 is
intended to be landed. The landing ring 128 is chosen to have a
slightly greater inner diameter than the outer diameter of the
existing conductor pipe 120 such that the landing ring 128 will
abut the upper end of the existing conductor pipe 120 in use.
However, depending upon the conditions, it may be preferable to
replace the spear 130 with an overshot (not shown but similar to
the overshot 36 of FIG. 2).
[0069] As shown in FIGS. 7 and 8, an additional conductor pipe 124
having a diameter of 30 inches (76.2 cm) in this example is
provided with a diverting end member in the form of a shoe 114. The
shoe 114 is shown in greater detail in FIG. 15 and is preferably
formed from a drillable material such as aluminium, hard plastics
such as polyurethane, a composite material or indeed any other
suitable drillable material and is generally provided in two main
portions, a head member 114 and a generally tubular collar 116
where there is a neck portion provided between the head member 114
and the collar 116, the neck portion providing a perpendicularly
extending shoulder which can be torqued against the lower end of
the replacement conductor 124, as will be subsequently described.
The head member of the shoe 114 has a paraboloid or bullet shaped
leading end having a curved substantially conical surface leading
to a gently rounded point in which a central hole 118 is provided.
The shoe 114 is coupled to the additional conductor pipe 124 via
the collar 116 that is arranged for insertion into the end of the
conductor pipe 124. A thread (not shown) is machined on an external
surface of the collar 116 and the lower end of the conductor pipe
124 has an internal thread provided therein. The collar 116 of the
shoe 114 is screwed into the conductor pipe 124 and can be secured
with aluminium dowels to ensure that there is no rotation between
the shoe 114 and the conductor pipe 124. The wide end of the head
member of the bullet shaped shoe 114 has an outer diameter which is
slightly larger (such as by 1/4 inch) than the outer diameter of
the conductor pipe 124. This prevents the joint between the shoe
114 and the conductor pipe 124 becoming stuck or separated as the
shoe 114 contacts the surface 104 of the whipstock 126.
[0070] An alternative shoe 115 is shown in FIG. 16. The end of the
shoe 115 is also bullet shaped with a connector 116 at the other
end. However, the head member of the shoe 115 has a plurality of
holes 118 provided therein. The purpose of the holes 118 in the
shoes 114, 115 is to allow fluid and muds therethrough to prevent a
significant pressure building up behind the shoes 114, 115 as the
shoes 114, 115 are drilled out (as will be subsequently described)
and thus impeding the progress of the conductor pipe 124 as it is
driven into the ground. Additionally, fluids can be pumped through
the holes 118 via a drillstring (not shown) coupled to the shoe
115. The fluids can wash away obtrusive cuttings from the leading
end of the shoe 115 if it becomes necessary.
[0071] It should be noted that any dimensions stated hereinafter
are given as an example only to aid understanding of the
embodiments and that actual dimensions will vary depending upon the
specific conditions such as the conductor pipe 120 being replaced,
the outer diameter of the replacement conductor 124, the inner and
outer diameters of the whipstock 126 and the inner and outer
diameters of the platform conductor guides 122.
FIRST EMBODIMENT CASE EXAMPLE 1
[0072] A first example of a method according to one embodiment of
the present invention will now be described with reference to FIGS.
5-9 of the drawings. The existing conductor pipe 120 in this
example has a diameter of 30 inches (76.2 cm) and is cut at least
60 feet (18.3 metres) below the seabed. Depending upon soil
conditions, a hole 132 of approximately 48 inches (1.22 metres) in
this example or larger is reamed in the mud above the cut conductor
pipe 120; if the soil is relatively hard, it will likely be
beneficial to drill a hole 132 larger than 48 inches (1.22 metres)
in diameter. In order to prevent the hole from collapsing during
whipstock 126 installation, heavy viscous mud can be pumped into
the hole 132 before withdrawing the drilling assembly (not shown)
used to ream the hole 132. The hole 132 can be drilled using a hole
opener or under reamer.
[0073] The drill string 94 is coupled to the box connection 110 of
the connector 108 within the whipstock 126. The drill string 94
passes through the hole 106 in the surface 104 of the whipstock
126. The whipstock 126 is then lowered through one or more
conductor guides 122 and the spear 130 is landed within the end of
the existing conductor pipe 120 with the whipstock trough 102
oriented in a predetermined location/direction. The drill string 94
is then rotated to decouple the threads 96 from the threads in the
box connection 110 of the connector 108. Once the drill string 94
is decoupled from the whipstock 126, it can be withdrawn back to
the platform floor.
[0074] Alternatively, different situations may mean that a
different connection method (i.e. non-screwthread or non-high
torque enabled connection) is preferred; in such cases, any other
suitable connection means may be used such as a "J" slot and latch
arrangement, an annular groove with locking ring arrangement etc.
etc.
[0075] The additional conductor pipe 124 with the attached shoe 114
is deployed through the one or more guide members 122 towards the
trough 102 of the whipstock 126. The inner diameter of the trough
102 in this example is 28.5 inches (72.4 cm). At its widest point,
the outer diameter of the shoe 114 in this example is 301/4 inches
(76.8 cm). However, since the shoe 114 is provided with a gently
rounded point, this locates the shoe 114 and attached conductor
pipe 124 correctly in the whipstock trough 102 and further downward
movement of the shoe 114, which has a larger maximum outer diameter
than the whipstock trough 102, forces the edges of the trough 102
to splay outwardly thereby accommodating the shoe 114 and the
conductor pipe 124 within the trough 102. The contact between the
shoe 114 and the surface 104 of the whipstock 126 causes the
conductor pipe 124 to deflect relative to the longitudinal axis of
the existing conductor pipe 120 as shown in FIG. 9. The conductor
pipe 124 can then be hammer driven to the required penetration
depth such that the additional conductor pipe 124 can thereafter
provide another well bore, in addition to the existing well bore
provided by the existing conductor pipe 120, to provide another
path for production fluids to flow from a reservoir to the
surface.
[0076] The above described method is also suitable where the
closest conductor guide is above around 65 feet (19.8 metres) the
seabed 134.
[0077] Running in the whipstock 126 separately from the additional
conductor pipe 124 enables the maximum possible outer diameter of
the conductor pipe 124 to be used with respect to the conductor
guides 122. The diameter of the whipstock trough 102 can also be
maximised with respect to the conductor guides 122. However,
despite the inner diameter of the trough 102 being equal to or less
than the outer diameter of the conductor pipe 124 it is still
possible to deflect and install the conductor pipe 124 due to the
shoe 114, which causes the whipstock 126 to splay thereby
increasing the diameter of the whipstock trough 102 such that it
can accommodate the end of the conductor pipe 124. Accordingly,
embodiments of the present invention do not require that the
additional conductor pipe 124 be 2 inches (5.1 cm) less in this
example than the inner diameter of the conductor guides 122. This
is a great advantage since it is always desirable to be able to use
the maximum conductor pipe 124 possible in the circumstances in
order to maximise potential hydrocarbon production rates or to
enable twin well drilling from one conductor pipe.
FIRST EMBODIMENT CASE EXAMPLE 2
[0078] A second method of installing a conductor pipe 124, whilst
using the bullet shaped shoe 114, will now be described.
[0079] The existing conductor pipe 120 is cut at least 60 feet
(18.3 metres) below the sea bed as per example 1. The hole 132 is
again reamed in the same manner as case example 1.
[0080] However, in case example 2, the whipstock 126 is shear
pinned to the lower end of the additional conductor pipe 124 with
the attached shoe 114. Accordingly, in this example 2, the initial
conductor pipe 124 and shoe 114 are run into the hole along with
the whipstock 126 until the whipstock spear 130 is landed into the
upper end of the existing conductor pipe 120. Further downward
movement of the additional conductor pipe 124 shears the shear pins
(not shown) causing the shoe 114 to enter in to the whipstock
trough 102 and thus deflection of the shoe 114 and lower end of
additional conductor pipe 124 occurs (as again shown in FIG. 9).
The conductor pipe 124 can then be hammer driven to the required
penetration depth (either with the shoe 114 still attached or with
the shoe 114 having been drilled out).
[0081] Running in the whipstock 126 simultaneously with the
additional conductor pipe 124 has the advantage that only one trip
is required to install the additional conductor pipe 124 as opposed
to the two separate trips of the case example 1. However, case
example 2 does not have the advantage of being able to maximise the
outer diameter of the additional conductor pipe 124 with respect to
the conductor guides 122.
SECOND EMBODIMENT CASE EXAMPLE 1
[0082] Another embodiment of the invention is shown in FIGS. 10-12.
The second described embodiment allows an additional conductor pipe
224 to be installed along a deflected path relative to an existing
conductor pipe 220 in circumstances where there is a conductor
guide relatively close to the seabed (say within 2 feet to 8 feet)
with the existing conductor pipe 220 cemented into the seabed and
providing the distance to the next conductor guide above that close
to the seabed is at least 50 feet (15.2 metres) or so.
[0083] The whipstock 226 is shown in FIGS. 10-12 and is generally
of the same construction as that described for the previous
embodiment. The whipstock 226 has a spear 230, a landing ring 228
and a trough 202 approximately 30 inches in length and defined by a
surface 204. The conductor pipe 224 has a shoe 214 attached to its
lower in use end. Furthermore, the lower in use end of the
conductor pipe 224 is shear bolted to an upper end of the whipstock
226 via shear bolts 248 passing through holes 249 in the whipstock
226 and the conductor pipe 224. The shear bolts 248 shear capacity
is determined from the tonnage of the conductor pipe 224 string
weight.
[0084] The shoe 214 of the second embodiment is shown in more
detail in FIGS. 13 and 14. The shoe 214 has an upper connector 216
for connecting the shoe 214 to the additional conductor pipe 224 in
the same manner as previously described. The shoe 214 has a face
212 angled at 45.degree. relative to the longitudinal axis of the
conductor pipe 224, since this angle is likely to be the most used
and therefore most preferred angle but other angles could be used
depending upon the conditions but the angle is likely to be in the
region between 20.degree. to 70.degree. with respect to the
longitudinal axis of the additional conduit and more likely will be
in the region between 30.degree. to 60.degree.. The shoe 214 is
provided with a central hole 218 in the face 212. The hole 218 in
the shoe 214 is also useful for guiding and centralising the
tapered drill bit after the installation process when the shoe 214
is to be drilled off the leading end of the conductor pipe 224.
[0085] FIG. 12 shows an upper and lower pipe guide 222U, 222L
respectively. The lower pipe guide 222L is maintained in position
by conductor guide bracings. A major guide brace 243 of the
platform is shown in the left hand side of the conductor guide 222L
in FIG. 12 and a minor guide brace 242 having a smaller diameter
than the major guide brace 242 is shown on the right hand side of
the conductor guide 222L. In many embodiments, the cemented
conductor pipe 220 is surrounded by four minor guide braces 242
spaced from one another by 90.degree. and therefore there is no
restriction on the orientation of the shoe 214.
[0086] The existing conductor pipe 220 is cut approximately 3 feet
(91.4 cm) above the lower conductor guide 222L. The additional
conductor pipe 224 coupled to the whipstock 226 is then lowered
through the upper conductor guide 222U. The whipstock 226 should be
positioned within the existing conductor pipe 220 such that the
trough 202 is angled towards the minor conductor guide brace 242,
and markings applied to the conductor pipe 224 as it is lowered at
the platform assists the operator to align the trough in the
desired rotational position. The spear 230 is landed in the
pre-existing conductor pipe 220 so that the landing ring 228 abuts
the upper edge of the existing conductor pipe 220. A force is then
applied to the conductor pipe 224 to shear the shear bolts 248.
Shearing the shear bolts 248 allows the conductor pipe 224 to
deflect by virtue of the whipstock trough 202. The shoe 214 (angled
at 45.degree. in this specific example) allows the end of the pipe
224 to avoid minor conductor guide brace 242 which does not impede
installation of the new conductor pipe 224 along its deflected
path, in that if the angled face of the shoe 214 contacts the minor
conductor guide brace 242, the angled face of the shoe 214 will
ride over and around the minor conductor guide brace 242. The
conductor pipe 224 is then hammer driven to the required depth
along its deflected path.
[0087] Accordingly, case example 1 of the second embodiment has the
advantage that only one trip is required to install the additional
conductor pipe 224 because it is lowered along with the whipstock
226. However, case example 1 does have the disadvantage that the
diameter of the new conductor pipe 224 is not maximised because of
the shear pin attachment points 248.
SECOND EMBODIMENT CASE EXAMPLE 2
[0088] The second embodiment case example 2 is largely similar to
the second embodiment case example 1 with the exception that the
whipstock 226 is run separately and is therefore not shear pinned
to the new conductor pipe 224. In the second embodiment case
example 2, the whipstock 226 is attached to a drill string 94 and
is lowered through the upper conductor guide 222U until it is
positioned within the existing conductor pipe 220. The trough 202
is angled in the same manner as second embodiment case example 1.
The drill pipe is then decoupled from the whipstock 226 and is
withdrawn back through the upper conductor guide 222U.
[0089] The new conductor pipe 224 with the attached shoe 214 is
then lowered through the upper conductor guide 222U until the
angled shoe 214 is located just above the whipstock 226. The new
conductor pipe 224 and angled shoe 214 are rotated until the angled
shoe 214 is in the desired rotational configuration with respect to
the whipstock 226. The new conductor pipe 224 is then further
lowered such that the conductor pipe 224 is deflected by virtue of
the whipstock trough 202. The angled face of the shoe 214 again
rides over and around the minor conductor guide brace 242 and the
new conductor pipe 224 can then be hammer driven to the required
depth along its deflected path.
[0090] The second embodiment case example 2 has the advantage that
the diameter of the new conductor pipe 224 can be maximised because
the new conductor pipe 224 is run separately from the whipstock 226
and therefore the outer diameter of the new conductor pipe 224 can
be chosen to be as large as possible as long as it still fits
through the upper conductor guide 222U.
[0091] The second embodiment has the great advantage that it can be
used to install an additional conductor in circumstances where the
existing conductor pipe has been cemented below the seabed, and
where there is a conductor guide located just above the seabed;
hitherto, it has not been possible to install an additional
conductor in such a scenario.
[0092] In both embodiments it is possible, and likely desirable, to
drill out the shoe 114, 214 just after the shoe 114, 214 has been
stabbed into the subsea surface and immediately prior to hammer
driving the conductor pipe 124, 224 into the desired position. In
this scenario, the conductor pipe 124, 224 is temporarily secured
to the rig and a smaller diameter drill pipe and drill bit (not
shown) are run down into the conductor pipe 124, 224 and the shoe
114, 214 is drilled out. The smaller diameter drill pipe and drill
bit are pulled out of the hole and hammer driving of the conductor
pipe 124, 224 can commence until final depth of penetration is
achieved. Alternatively, depending upon the formation, it may be
more desirable to hammer drive the conductor pipe 124, 224 to the
final depth of penetration and then drill out the shoe 114,
214.
[0093] The embodiments described herein have cost and time
advantages over the prior art systems for installation of
additional conductor pipes (124; 224) from an existing production
platform (50); furthermore the outer diameter of the additional
conductor pipe (124; 224) can be maximised.
[0094] Modifications and improvements can be made without departing
from the scope of the invention. For instance, the shoe 114, 214
could be formed of a different drillable material such as a hard
plastic which may be polyurethane. Also, the lower face of the
landing ring 128 may be provided with teeth 129 shown in FIG. 4
which are adapted to bite into the upper end of the existing
conductor 120, 220. The teeth 129 may point directly downwards or
may point at an angle in one or both rotational directions in order
to further prevent unwanted rotation occurring between the
whipstock 126, 226. Furthermore, the various diameters and lengths
of the components described herein can be varied in order to suit
the particular platform involved.
[0095] Any feature of any aspect of any embodiment described herein
may be combined with any feature of any aspect of any other
embodiment described herein mutatis mutandis.
* * * * *