Patent Application
20090266559
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.
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.
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
The conventional method shown in
Once the whipstock 26 of
The method of
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 ¾ 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 ¾ 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.
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.
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:
(a) providing a deflecting member at a lower end of the additional conduit;
(b) installing a path diverting means at or towards an upper end of an existing conduit;
(c) delivering the lower end of the additional conduit towards the upper end of the existing conduit; and
(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.
Preferably, the method further comprises step (e) of installing the additional conduit along the deflected path.
Step b) may be carried out simultaneously with step c). Alternatively, step b) may be carried out prior to step c).
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.
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° to 70°, and more preferably can be angled in the region of between 30° to 60°, and most preferably can be angled at 45° with respect to the longitudinal axis of the additional conduit although other angles, as conditions may warrant, will suffice.
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.
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.
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.
The deflecting member can be provided with one or more holes extending therethrough.
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.
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.
The inner diameter of the path diverting means can be less than the outer diameter of the additional conduit.
The coupling means can be adapted to prevent rotation between the additional conduit and the deflecting member.
According to a second aspect of the present invention, there is provided a method of installing an additional subterranean conduit, comprising the steps of:
(a) installing a path diverting means at or towards an upper end of an existing conduit using a deployment means;
(b) removing the deployment means following installation of the path diverting means;
(c) delivering a lower end of the additional conduit towards the upper end of the existing conduit;
(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
(e) installing the additional conduit along the deflected path.
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.
The method typically further relates to delivering an additional subterranean conduit along a deflected path from an existing conduit.
The method can include removing a portion of the existing conduit prior to commencing step (a).
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.
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.
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.
Following step (a), the method preferably further comprises decoupling the elongate member and the path diverting means and withdrawing the elongate member.
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.
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.
The method may further include providing the deflecting member with an angled end member.
The method may include angling at least a portion of the deflecting member in the region of between 20° to 70°, and more preferably in the region of between 30° to 60°, and most preferably at 45° 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).
According to another aspect of the present invention, there is provided a method of installing an additional subterranean conduit, comprising the steps of:
(a) providing the additional conduit with a deflecting member coupled to an end thereof;
(b) detachably coupling an end of a path diverting means to a portion of the additional conduit;
(c) installing the path diverting means and coupled additional conduit at or towards an end of an existing conduit;
(d) applying a longitudinal force to the additional conduit and thereby decoupling the additional conduit from the path diverting means;
(e) deflecting the additional conduit to thereby urge the additional conduit along a deflected path relative to the existing conduit; and
(f) installing the additional conduit along the deflected path.
The method typically further relates to delivering an additional subterranean conduit along a deflected path from an existing conduit.
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.
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.
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.
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.
Embodiments of the invention will now be described with reference to and as shown in the accompanying drawings, in which:
A whipstock is shown generally at 126 in
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.
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
As shown in
An alternative shoe 115 is shown in
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.
A first example of a method according to one embodiment of the present invention will now be described with reference to
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.
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.
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 30¼ 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
The above described method is also suitable where the closest conductor guide is above around 65 feet (19.8 metres) the seabed 134.
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.
A second method of installing a conductor pipe 124, whilst using the bullet shaped shoe 114, will now be described.
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.
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
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.
Another embodiment of the invention is shown in
The whipstock 226 is shown in
The shoe 214 of the second embodiment is shown in more detail in
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° 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.
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.
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.
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.
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.
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.
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.
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.
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
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.
| Number | Date | Country | Kind |
|---|---|---|---|
| 0524750.7 | Dec 2005 | GB | national |
| 0620101.6 | Oct 2006 | GB | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/GB2006/004497 | 12/1/2006 | WO | 00 | 8/27/2008 |
