Downhole method and apparatus

Abstract

A method of injecting fluid into a formation, comprises exerting a mechanical force on a wall of a bore extending through a formation to modify the permeability of the formation; and injecting fluid into the modified formation. The mechanical force is exerted through inflation of at least one pressure deformable member mounted on a base member with a retaining ring.

Claims

1. A downhole apparatus comprising a base pipe, a plurality of axially extending pressure deformable members mounted around the base pipe and at least one circumferential retaining ring axially spaced from ends of the deformable members and located externally of the members radially spaced from the base pipe and the at least one circumferential retaining ring always maintained disconnected from the base pipe by the deformable members and the each one of the plurality of deformable members is always non-concentric with the base pipe.

2. The apparatus of claim 1, wherein the deformable members are initially located on the base pipe in a deflated configuration and the retaining ring located over the deflated members.

3. The apparatus of claim 1, wherein a plurality of rings are provided.

4. The apparatus of claim 3, wherein the at least one circumferential retaining ring includes respective rings provided at each end of a pipe joint.

5. A downhole method comprising: locating a plurality deformable members on a base pipe in a deflated configuration, wherein the each one of the plurality of deformable members is always non-concentric with the base pipe; locating at least one retaining ring over the deflated deformable members such that the at least one retaining ring is radially spaced from the base pipe by the deformable members and axially spaced from axial ends of the deformable members to thereby retain the deformable members radially; and inflating the deformable members to extend radially beyond the at least one retaining ring to thereby retain the at least one ring axially along the deformable members; and maintaining the at least one retaining ring always disconnected from the base pipe by the deformable members.

6. The method of claim 5, wherein inflating the deformable members includes inflating two portions of the deformable members adjacent the at least one ring on opposite axial sides of the at least on retaining ring.

7. The method of claim 5, wherein locating at least one retaining ring includes providing respective retaining rings over the deformable members at each end of the base pipe.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) These and other aspects of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

(2) FIG. 1 is a schematic sectional view of a fluid injection operation in accordance with an embodiment of the present invention;

(3) FIG. 2 is a schematic sectional view of a through tubing sand control operation in accordance with another embodiment of the present invention;

(4) FIG. 3 is a sectional view of part of the apparatus of FIG. 2;

(5) FIG. 4 is a schematic sectional view of a gravel packing operation in accordance with a further embodiment of the present invention;

(6) FIG. 5 is a sectional view of a completion including apparatus in accordance with an embodiment of the present invention;

(7) FIG. 6 is a sectional view of part of the apparatus of FIG. 5;

(8) FIG. 7 is a sectional view of apparatus of an embodiment of the present invention in a bore intersecting two formations;

(9) FIG. 8 is a sectional view of a sand control apparatus in accordance with an embodiment of the invention;

(10) FIG. 9 is a view of the apparatus of FIG. 8 in an extended configuration;

(11) FIG. 10 is an external view of the apparatus of FIG. 8;

(12) FIG. 11 is a view of an apparatus of an embodiment of the present invention including retaining rings;

(13) FIG. 11A is a schematic end view of the apparatus of FIG. 11 illustrating the retaining rings located over deflated chambers;

(14) FIG. 11B is a schematic end view of the apparatus of FIG. 11 illustrating the retaining rings located over inflated chambers; and

(15) FIG. 12 is a view of a chamber-fixing feature of an embodiment of the present invention.

DETAILED DESCRIPTION OF THE DRAWINGS

(16) Reference is first made to FIG. 1 of the drawings, which illustrates apparatus 10 in accordance with an embodiment of the invention. The apparatus is illustrated in a deployed, installed configuration, located in a bore 12 intersecting a formation 14. The apparatus 10 comprises a base tube 16 forming part of a tubing string, such as completion, which provides communication to surface. Mounted on a portion of the base tube is a plurality of hollow members 18 which define fluid pressure-deformable chambers. The wall of the base tube 16 defines flow ports 20 which allow fluid to flow between the formation and the interior of the tube 16, and then to surface. Valves, such as inflow control devices (ICDs), may be provided to control the flow of fluid through the ports 20.

(17) A sand control element 22 in the form of a sand screen is wrapped around the members 18 and a drainage layer 24 is provided beneath the element 22. Packing elements 26, 28 are also provided around the base tube 16 and the ends of the members 18 at the upper and lower ends of the sand screen 22.

(18) The hollow members 18 are mounted side-by-side on the base tube 16. The members 18 are formed by cold rolling flat plate but may also be formed of metal tubes which have been flattened. The members 18 may extend substantially axially of the tube 16, but in this embodiment are in a helical configuration. The members 18 are connected to a source of pressurized fluid on surface via appropriate control lines 20, which source may be utilized to inflate the members 18 such that the inflated members 18 collectively define a larger outer diameter, as illustrated in FIG. 1. In other embodiments a pressurized activation chamber may form part of the apparatus 10 and be run into bore, as described below with reference to FIG. 2. In any event, the apparatus 10 is configured such that inflation of the members 18 brings the sand screen 22 and the packing members 26, 28 into contact with the bore wall. The inflation pressure, and the construction and configuration of the members 18, is also selected to exert and maintain a predetermined radial force on the bore wall, as will be described below. The members 18 may be made in accordance with the teaching of WO 2009/001073 and WO 2009/001069, the disclosures of which are incorporated herein by reference in their entirety, or in accordance with the other aspects or embodiments of the present invention, as described herein.

(19) In use, the apparatus 10, with the members 18 in the initial flattened configuration, is run into the bore 12 on the tubing string and located at an appropriate point in the bore. In FIG. 1, the apparatus 10 has been positioned with the portion of the tube 16 carrying the members 18 straddling a formation 14 which is intersected by the bore 12.

(20) Fluid is applied from surface and pressure increased to inflate the members 18 and push the sand screen 22 and the packing elements 26, 28 into contact with the bore wall, as illustrated in FIG. 1. As described below, the pressure of the fluid may be controlled to provide a predetermined load or force on the bore wall. The load or force provided by the members 18 may be substantially constant, or may be varied over time.

(21) If the formation is formed of relatively low permeability rock the members 18 may be inflated using sufficiently high pressure fluid to subject the rock adjacent the bore wall to a stress above the failure strength of the rock. This results in brittle fracturing of the rock, and increases the permeability of the rock. An operator may then pump fluid at high pressure through the string to further fracture the rock. The fluid may contain chemicals or treatment agents, such as stabilizing agents or proppants. Alternatively, the operator may inject fluid into the formation to, for example, maintain or increase production at another part of the formation.

(22) The operator may subsequently reduce the pressure of the fluid in the tubing string and permit fluid to flow from the formation 14 into the string and on to surface.

(23) During injection of fluid into the formation or production of fluid from the formation 14 the pressure within the members 18 may be varied to change the force applied to the bore wall by the apparatus 10 to maximize the bore wall permeability and thus maintan the injection or production rates as high as possible.

(24) Alternatively, or in addition, the pressure within the members 18 may be selected or varied to decrease the permeability of the rock, and thus decrease or minimize the flow of fluid into or from the formation 14. This may be useful if the formation 14 is at relatively low pressure and production fluid from higher pressure formations, or treatment or other fluid intended for other formations or intended to remain in the bore to provide a pressure barrier, is flowing into the formation 14. Also, if it is desired to reduce production from the formation, for example if the formation 14 is producing too much water, the permeability of the rock may be reduced. This method of decreasing the permeability of the rock forms a separate aspect of the present invention.

(25) In other embodiments the force created by the members 18 may be selected to control the production of particulates from the formation 14. Further embodiments may utilize an inflation fluid which solidifies after a predetermined period. This may limit the ability of the operator to control the force applied by the members 18 after initial inflation but may avoid any risk of the members 18 deflating.

(26) A completion or other tubing string may be provided with any number of apparatus 10, and each apparatus may be under common or individual control. The individual apparatus may be inflated simultaneously or separately. Each apparatus may exert the same force on the bore wall or may exert an individually determined force. The force exerted by each apparatus may be constant or may vary over time.

(27) FIG. 2 of the drawings illustrates a through-tubing sand control apparatus 50 in accordance with an embodiment of the present invention. The apparatus 50 is illustrated in a deployed extended configuration within a bore 52 intersecting a formation 54, the bore having previously been lined with a perforated liner 56. The apparatus comprises a base pipe 58 around which are mounted two layers of inflatable hollow members 60. The members 60 are initially provided on the pipe 58 in a flattened configuration and describe a relatively small external diameter, allowing the apparatus 50 to be run into a bore through existing tubing 62. The members 60 are coupled to an appropriate source of pressurized fluid, in this example a plurality of gas bottles or pressurized nitrogen chambers 64 mounted on the distal end of the base pipe 58. The flow of fluid from the bottles 64 to the members 60 is controlled by a valve 66 which may be activated by any appropriate mechanism, such as by RFID tags which are dropped or pumped from surface.

(28) As is apparent from FIG. 3, the members 60 extend axially of the base pipe 58, and are nested to provide essentially complete circumferential support for a sand screen 68 and a drainage layer 70.

(29) In use, the apparatus 50 will typically be deployed only if sand production from the formation 54 through the perforated liner 56 reaches an unacceptable level. The apparatus 50 is then run into the bore 52, through the existing tubing 62, to locate the apparatus 50 adjacent the formation 54. The valve 66 is then opened to allow fluid to flow from the bottles 64 to inflate the members 60. The diameter described by the members 60 increases significantly and brings the sand screen 68 into contact with the inner surface of the liner 56. Thus, fluid from the formation 54 now has to pass through the sand screen 68 before entering the bore 52, such that the flow of particulates into the bore 52 will be substantially reduced.

(30) FIG. 4 of the drawings illustrates apparatus 100 in accordance with an embodiment of the invention deployed within a bore 102 including a gravel pack 104. As with the embodiments described above, the apparatus includes a number of pressure deformable members 106 mounted around a base pipe 108 and supporting a sand screen 110. The sand screen 110 may take any suitable form, and may be a woven element, which may be expandable. The pressure deformable members 106 communicate with the interior of the base pipe 108 via one-way valves, such that the members 106 may be inflated simply by pressurising the interior of the base pipe 108.

(31) The apparatus 100 is run into the bore in an initial smaller diameter configuration. The gravel pack 104 is then circulated into the annulus 112 between the sand screen 110 and the bore wall 114. Following this, the members 106 are inflated and the gravel 104 is compressed and stressed. Furthermore, the wall of the bore may also be stressed. The members 106 are provided with a degree of excess expansion, that is the members 106 will extend to compress the gravel 104, and the bore wall, even if a section of annulus 112 has not been fully packed, or the bore wall 114 is irregular. Thus, the apparatus 100 is compliant and provides an assured degree of compression to the gravel 104. This assists in providing a consistent gravel pack providing consistent sand retention and flow characteristics.

(32) Once the well is producing, formation fluid will flow from the surrounding formation, through the gravel 104 and sand screen 110, around the members 106 and into the base pipe 108, before flowing to surface. The gravel pack 104 serves to stabilise the well bore wall and prevents or limits the migration of fines from the bore wall, or fines entrained with the formation fluid, into the pipe 108. The sand screen 110 will also serve to prevent particulates from passing into the pipe 108, and will also serve to retain the gravel 104.

(33) FIGS. 5 and 6 of the drawings illustrates a completion 150 provided with apparatus 152a,b,c in accordance with an embodiment of the invention. The completion 150 is provided in a horizontal bore section 154. Each apparatus 152a,b,c comprises a base pipe 156, pressure deformable members 158 and a sand screen 160.

(34) In use, the completion 150 is assembled such that, when the completion is run into the bore, each apparatus 152a,b,c is positioned adjacent a selected formation or production zone 162a,b,c. The members 158 are then inflated such that the sand screens 160 contact the opposing bore wall and exert an appropriate force on the bore wall to, for example, increase the rock permeability. The forces applied on the bore wall may be varied over time to compensate for reductions in rock pore pressure, as discussed in more detail in WO 2009/001073 and WO 2009/001069.

(35) Each apparatus 152a,b,c may create a different bore wall stress. For example, the apparatus 152a at the heel 164 may exert a higher force selected to reduce fluid production from an elastic high porosity formation, and minimize the risk of excess water production. If the risk of excess water production recedes, the apparatus 152a may be deflated and the bore wall stress reduced, increasing formation porosity.

(36) Furthermore, the inflation/deflation of fluid supplied to individual members 158 may be individually controlled, for example the members 158a,b on the upper and lower faces of an apparatus 152 may be deflated at a different rate to the members 158c,d on the sides of the apparatus.

(37) Reference is now made to FIG. 7 of the drawings, which illustrates apparatus 200a,b in accordance with an embodiment of the present invention, an upper apparatus 200a straddling a low pressure formation 202a and a lower apparatus 200b straddling a high pressure formation 202b.

(38) Both apparatus 200 include a base pipe 204 carrying a plurality of pressure deformable chambers 206. Packer elements 208 are provided at the ends of each apparatus 200 and a sand control element 210 is wrapped around each collection of chambers 206.

(39) The ends of the chambers 206 are formed of more readily deformable material than the centre sections such that, when the chambers 206 are inflated, the ends of the chambers 206 tend to deform and extend before the centre sections. Thus, the packer elements 208 are extended and engage the bore wall before the sand control element-carrying centre sections are extended.

(40) As with the other embodiments, the tubing string comprising the apparatus is made up with the chambers 206 in an initial flattened configuration. Once the string has been run into the bore and the apparatus 200a,b positioned across the formations 202a,b, the lower apparatus 200b is actuated or inflated by activating a string-mounted fluid pressure source 211. The activation may comprise signaling a sensor on the source 211, which signal may comprise a pressure signature or the like. The pressure source 211 contains two liquid components which are mixed as the components are expelled into the chambers 206b. As noted above, the ends of the chambers 206b expand first, followed by the remainder of the chambers. The pressure source 211 is configured to supply the liquid at a predetermined pressure to create a predetermined force on the wall of the bore.

(41) The mixed liquid components react and cure within the chambers 206b to form a solid filling which prevents deflation of the chambers thus maintaining the inflated chamber form, and also maintaining the force on the bore wall.

(42) The high pressure formation 202b is now isolated and flow of fluid from the formation 202b into the base pipe 204 may now be controlled through operation of ICDs provided on the apparatus 200b.

(43) The high pressure fluid from the formation 202b is also in communication with a control line 212 which extends from the lower apparatus 200a to the upper apparatus 200b via a remotely activated valve 214. Thus, once the lower apparatus 200b has been actuated and the formation 202b isolated, the valve 214 may be opened and the high pressure fluid from the formation 202b used to actuate the upper apparatus 200a.

(44) Reference is now made to FIGS. 8, 9 and 10 of the drawings, which are schematic illustrations of details of an apparatus 250 in accordance with an embodiment of the present invention. FIG. 8 shows the apparatus 250 in an initial configuration, in which a series of axially extending fluid pressure deformable chambers 252 are mounted about a base pipe 254. The chambers 252 are initially in a flattened deflated configuration. Mounted on each chambers 252 is an axially extending apertured bridging member 256, one edge of the bridging member being fixed to a respective chamber 252 and the other edge of the member 256 extending to rest on an adjacent chamber 252. A single-piece sand control element 258 is wrapped around the chambers 252 and the bridging members 256, the edges of the element 260, 262 overlapping. As may be seen from FIG. 10, overlapping edges extend helically along the apparatus 250, and are thus inclined to the main axis of the apparatus.

(45) The sand control element 258 features a coating of hardened material, for example a diamond coating. Such a coating resists erosion of the element 258 and also facilitates relative sliding movement between the overlapping edges 206, 262 and other elements of the apparatus 250, and minimises the risk of damage to the edges 260,262 during the expansion process. In other embodiments the whole element 258 could be formed of a relatively hard material.

(46) On filling the chambers 252 with high pressure fluid the chambers 252 deform and radially extend such that the diameter defined by the apparatus 250 increases, as shown in FIG. 9. In particular, if the apparatus 250 is located in a bore, the sand control element 258 will be pushed into contact with the surrounding bore wall. The sand control element 258 floats on the bridging members 256, and as the chambers inflate the overlap at the edges of the element decreases. Also, the bridging members 256 slide over one another, collectively maintaining a generally cylindrical form and bridging the gaps that form between the inflated chambers 252. The bridging members 256 thus ensure that the sand control element 258 is fully supported around the circumference of the apparatus 250 and that the element 258 applies a substantially constant force to the bore wall.

(47) Reference is now made to FIG. 11, 11A an 11B of the drawings, which illustrates an apparatus 300 in accordance with an embodiment of the present invention. In this embodiment pressure deformable chambers 302 are retained on a base pipe 304 formed by a single pipe joint by retaining rings 306 provided adjacent the pipe ends.

(48) The rings 306 may be located over the flattened deflated chambers 302, (FIG. 11A) and radially separated from the base pipe 304 by the chambers 302, and when the chambers 302 are inflated and deformed (FIG.11B) the rings 306 retain their form and constrain the portions of the chamber 302 beneath the rings 306. The portions of the chambers 302 adjacent the rings 306 will extend radially beyond the rings 306, as illustrated in broken outline in FIG. 11, and thus serve to retain the rings 306 axially while the rings 306 retain the chambers 302 radially.

(49) The chambers 302 are formed of tubes in which the tube ends have been welded closed by a rounded weld. The use of a tapered or rounded weld reduces the build-up of stresses at the end of the chamber during inflation of the chamber 302. The rings 306 are longitudinally spaced from the tube ends of the chambers 302.

(50) Reference is now made to FIG. 12 of the drawings, which illustrates a method of fixing a pressure deformable chamber 350 to a base pipe 352. The chamber 350 is formed by hollow steel member 354 with a wall 356 defining first and second apertures 358, 360. An operator uses the second aperture 360 to gain access to the first aperture 358 and weld the member 354 to the base pipe 352 at the first aperture 358. The welding operation creates a fluid-tight seal at the first aperture 358. The second aperture is then closed with a patch 362, to seal the hollow member 354.

(51) Although the above embodiments are described with reference to fluid injection or production operations, the apparatus of the present invention may also be utilized during a drilling operation, for example an apparatus in accordance with an embodiment of the invention may be run into a bore and activated to stabilize an unstable or swelling formation, to reduce or prevent fluid losses into a low pressure formation, or to stem the flow of fluid into a bore from a high pressure formation. The apparatus may be mounted on the drill string or may be run in separately of the drill string. The apparatus may be removed from the bore once the situation has been stabilized or other measures have been put in place. The removal of the apparatus from the bore may be facilitated by deflating the pressure deformable chambers/elements and permitting ambient pressure in the bore to flatten the chambers, or by utilizing elastic-walled chambers. Alternatively, the apparatus may remain in the bore. In other embodiments, parts of the apparatus may remain in the bore while other parts of the apparatus are retrieved. For example, the apparatus may carry an expandable or extendable fluid impermeable element, and inflation of the fluid deformable chambers may locate the element against the bore wall. The fluid impermeable element may be configured to retain the larger diameter when the chambers are deflated, or the element may be held in place by differential pressure. The element may thus serve to prevent or minimise losses into a low pressure formation or may be utilized to minimise problems due to differential sticking.