DOWNHOLE COMPLETION SYSTEM

Abstract

The present invention relates to a completion system for connecting several screens into a well tubular structure mounted from base pipe sections. The completion system comprises a first screen assembly and a second screen assembly, each screen assembly comprising a base pipe section mounted as part of the well tubular structure having a longitudinal extension, the base pipe section having an outer face, and a tubular screen element surrounding and being connected to the outer face of the base pipe section, the tubular screen element having an outer diameter, and an assembly connection part for connecting an end of the first screen assembly with an end of the second screen assembly, wherein the completion system further comprises a first tubular member having an inner diameter which is equal to or larger than the outer diameter of the tubular screen element, the first tubular member being arranged opposite the assembly connection part so that fluid flowing in through the tubular screen element of one of the screen assemblies flows on the outside of the assembly connection part. Furthermore, the present invention relates to a completion method and a production method for producing hydrocarbon-containing fluid from a reservoir into a well tubular structure.

Claims

1. A completion system for connecting several screens into a well tubular structure mounted from base pipe sections, comprising: a first screen assembly and a second screen assembly, each screen assembly comprising: a base pipe section mounted as part of the well tubular structure having a longitudinal extension, the base pipe section having an outer face, and a tubular screen element surrounding and being connected to the outer face of the base pipe section, the tubular screen element having an outer diameter, and an assembly connection part for connecting an end of the first screen assembly with an end of the second screen assembly, wherein the completion system further comprises a first tubular member having an inner diameter which is equal to or larger than the outer diameter of the tubular screen element, the first tubular member being arranged opposite the assembly connection part so that fluid flowing in through the tubular screen element of one of the screen assemblies flows on the outside of the assembly connection part.

2. A completion system according to claim 1, further comprising a first tubular member connector and a second tubular member connector, each tubular member connector having an inner diameter which is equal to or larger than the outer diameter of the tubular screen element, and the first tubular member is maintained in at least the longitudinal extension by the tubular member connectors.

3. A completion system according to claim 2, wherein each screen assembly comprises a screen element fixation part adapted to fixate the tubular screen element to the base pipe section.

4. A completion system according to claim 3, wherein the first tubular member connector is arranged so as to at least partly overlap the screen element fixation part of the first screen assembly, and the second tubular member connector is arranged so as to at least partly overlap the screen element fixation part of the second screen assembly.

5. A completion system according to claim 2, wherein the tubular member connectors have internal threads.

6. A completion system according to claim 3, wherein the screen element fixation part has an external thread.

7. A completion system according to claim 1, wherein the first tubular member connector and the second tubular member connector are slidable on the outer face of the base pipe section during assembly of the first screen assembly and the second screen assembly.

8. A completion system according to claim 1, further comprising a flow section mounted as part of the well tubular structure for allowing fluid to flow into or out of the well tubular structure.

9. A completion system according to claim 1, further comprising a second tubular member arranged opposite the flow section so that fluid flowing in through the tubular screen element of one of the screen assemblies flows on the outside of the base pipe section and in through the flow section, or vice versa.

10. A completion system according to claim 1, further comprising at least one annular barrier assembly comprising: a base pipe section for being mounted as part of the well tubular structure, the base pipe section comprising an aperture, an expandable sleeve surrounding the base pipe section and having an inner face facing the base pipe section and an outer face facing a wall of a borehole or another well tubular structure, each end of the expandable sleeve being connected with the base pipe section, and an annular space between the inner face of the expandable sleeve and the base pipe section.

11. A completion method for completing the completion system according to claim 1 in a borehole of a well, said completion method comprising: providing the first screen assembly, mounting a second screen assembly to the first screen assembly by means of the assembly connection part, sliding the first tubular member along the tubular screen element of the first screen assembly or the second screen assembly, and positioning the first tubular member opposite the assembly connection part.

12. A completion method according to claim 11, wherein the completion system comprises a first tubular member connector and a second tubular member connector, each having an outer diameter which is equal to or larger than the outer diameter of the tubular screen element, and wherein the first tubular member connector and the second tubular member connector are moved along the longitudinal extension towards the first tubular member to fasten the first tubular member opposite the assembly connection part.

13. A completion method according to claim 11, wherein the completion system further comprises a third screen assembly and a flow section mounted between the second screen assembly and the third screen assembly.

14. A completion method according to claim 11, wherein the completion system further comprises a second tubular member which is slid along the tubular screen element of the second screen assembly or the third screen assembly, positioning the second tubular member opposite the flow section.

15. A production method for producing hydrocarbon-containing fluid from a reservoir into a well tubular structure, comprising: letting fluid in through a first screen assembly of a completion system according to claim 1, letting the fluid past an annular space between the first tubular member and the assembly connection part, letting the fluid flow between the tubular screen element and the base pipe section of a second screen assembly, and letting the fluid flow into an annular space under a second tubular element and into a flow section and into the well tubular structure.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0066] The invention and its many advantages will be described in more detail below with reference to the accompanying schematic drawings, which for the purpose of illustration show some non-limiting embodiments and in which

[0067] FIG. 1 shows a cross-sectional view of a completion system,

[0068] FIG. 2 shows a cross-sectional view of another completion system,

[0069] FIG. 3 shows a cross-sectional view of another completion system having annular barrier assemblies,

[0070] FIG. 4 shows a cross-sectional view of another completion system having a flow section,

[0071] FIG. 5 shows a cross-sectional view of another completion system having centralisers, and

[0072] FIG. 6 shows a cross-sectional view of another completion system.

[0073] All the figures are highly schematic and not necessarily to scale, and they show only those parts which are necessary in order to elucidate the invention, other parts being omitted or merely suggested.

DETAILED DESCRIPTION OF THE INVENTION

[0074] FIG. 1 shows a completion system 1 for connecting several screen assemblies 4 into a well tubular structure 2. Each screen assembly comprises a base pipe section 3 mounted to form part of the well tubular structure, so that the base pipe section and the well tubular structure have coincident centre axes along a longitudinal extension 5 of the well tubular structure. The base pipe sections 3 are mounted together by means of an assembly connection part 8 for connecting an end 9 of a first screen assembly 4, 4a with an end 10 of a second screen assembly 4, 4b. Each base pipe section 3 has an outer face 6 and a tubular screen element 7 of each screen assembly, which tubular screen element surrounds the outer face of the base pipe section and is connected to the outer face of the base pipe section.

[0075] The completion system further comprises a first tubular member 11 having an inner diameter ID.sub.M which is equal to or larger than an outer diameter OD.sub.E of the tubular screen element. The first tubular member 11 is arranged opposite the assembly connection part 8 forming an annular space 24, so that fluid flowing in through the tubular screen element 7 of one of the screen assemblies 4 flows on the outside of the assembly connection part 8. By having the first tubular member 11, the base pipe sections 3 can be mounted by assembly connection parts 8 being standard casing collars or casing couplings. Thus, the assembly connection parts 8 do not have to be complicated, specially designed couplings which have to undergo separate qualifications, and such specially designed couplings may also increase the overall costs associated with the completion system 1 and thus the well.

[0076] In FIG. 2, the completion system 1 further comprises a first tubular member connector 12, 12a and a second tubular member connector 12, 12b having inner diameters ID.sub.C which are equal to or larger than the outer diameter OD.sub.E of the tubular screen element 7. The first tubular member 11 is maintained in at least the longitudinal extension 5 by the tubular member connectors 12, 12a, 12b. By having tubular member connectors having an inner diameter which is equal to or larger than the outer diameter of the tubular screen element, the tubular member connectors are able to slide along the tubular screen element 7 during mounting of the completion system 1, and the first tubular member 11 is then also able to slide along the tubular screen element 7 and remain opposite the tubular screen element 7 while the first screen assembly 4, 4a and the second screen assembly 4, 4b are mounted by means of the assembly connection part 8 which may be a standard casing collar or casing coupling. During connection of two base pipe sections 3 of the two screen assemblies 4, the tools at the rig need to get a firm grip around the base pipe sections 3, and during this connection step there is no room for the first tubular member 11, nor the tubular member connectors 12, 12a, 12b fastening the first tubular member 11. Thus, during mounting of the base pipe sections 3, the first tubular member 11 and the first tubular member connector 12, 12a are arranged opposite the tubular screen element 7 of the first screen assembly 4, 4a, and the second tubular member connector 12, 12b is arranged opposite the tubular screen element 7 of the second screen assembly 4, 4b. After mounting of the base pipe section 3 of the first screen assembly 4, 4a with the base pipe section 3 of the second screen assembly 4, 4b by means of the assembly connection part 8, the first tubular member 11 is slid along the tubular screen element 7 and arranged opposite the assembly connection part 8, and then the first tubular member connector 12, 12a and the second tubular member connector 12, 12b are slid along the tubular screen elements 7, fastening the first tubular member 11 from either side in a position opposite the assembly connection part 8, so that fluid from the first screen assembly 4, 4a can flow on the outside of the assembly connection part 8 underneath the second screen assembly 4, 4b. Thus, the first tubular member and the base pipe section form an annular flow channel 24a.

[0077] Each screen assembly 4 comprises a screen element fixation part 14 adapted to fixate the tubular screen element 7 to the base pipe section. The screen element fixation part 14 has a plurality of flow channels 21 distributed around the periphery of the base pipe section 3. The flow channels 21 extend along the longitudinal extension to fluidly connect the screen with the annular flow channel 24a. The first tubular member connector 12, 12a is arranged so as to partly overlap the screen element fixation part 14 of the first screen assembly 4, 4a, and the second tubular member connector 12, 12b is arranged so as to partly overlap the screen element fixation part 14 of the second screen assembly 4, 4b. In order to be able to be fastened to the screen element fixation parts, the tubular member connectors 12 have internal threads and the screen element fixation part 14 has an external thread for engagement with the internal threads of the tubular member connectors 12. Thus, the tubular member 11 is not directly connected to the assembly connection part 8 but bridges or straddles over the assembly connection part, forming a distance D from the outer face of the assembly connection part to the tubular member 11, as shown in FIG. 2. The assembly connection part 8 has an outer diameter OD.sub.P which is larger than the outer diameter of the base pipe section 3, and the distance between the tubular member 11 and the base pipe section is greater than the distance D. The assembly connection part 8 may also have an outer diameter OD.sub.P which is equal to the outer diameter of the base pipe section 3. The assembly connection part is one way of assembling two base pipes/casings. Another way could be by means of integral flush joint casings or casings with upset connections.

[0078] During mounting of the base pipe sections 3, the first tubular member connector 12, 12a is arranged opposite the tubular screen element 7 of the first screen assembly 4, 4a, and the first tubular member 11 and the second tubular member connector 12, 12b are arranged opposite the tubular screen element 7 of the second screen assembly 4, 4b. After mounting of the base pipe section 3 of the first screen assembly 4, 4a with the base pipe section 3 of the second screen assembly 4, 4b by means of the assembly connection part 8, the first tubular member 11 is slid along the tubular screen element 7 of the second screen assembly and arranged opposite the assembly connection part 8, and subsequently the first tubular member connector 12, 12a and the second tubular member connector 12, 12b are slid along the tubular screen elements 7, fastening the first tubular member 11 from either side in a position opposite the assembly connection part 8, so that fluid from the first screen assembly 4, 4a is able to flow on the outside of the assembly connection part 8 underneath the second screen assembly 4, 4b. Thus, the first tubular member and the base pipe section form an annular flow channel 24a. By arranging the first tubular member 11 opposite the tubular screen element 7 of the second screen assembly 4, 4b, the first tubular member 11 is to be mowed downwards during mounting and not upwards as if it was mounted on the first screen assembly. The tubular member 11 is then held in place during mounting by a fastening tool (not shown).

[0079] As shown in FIG. 2, the assembly connection part 8 has a solid massive wall and the tubular member 11 is solid or massive, and the wall of the assembly connection part and tubular member is thus unperforated, meaning that the assembly connection part and the tubular member have no openings or channels.

[0080] The thread of the first tubular member connector 12, 12a is a left hand thread and the thread of the second tubular member connector 12, 12b is a right hand thread. The first tubular member connector 12, 12a having the left hand thread is arranged closest to the top of the well in relation to the tubular member 11 which is fastened to the second tubular member connector 12, 12b, and the second tubular member connector 12, 12b having the right hand thread is thus arranged on the other side of the tubular member. During insertion of the well tubular structure in the borehole, the well tubular structure is often rotated clockwise, and the first tubular member connector 12, 12a and second tubular member connector 12, 12b are then further tightened instead of being unscrewed when run in hole. In situations in which the tubluar structure has to be rotated anti-clockwise, the arrangement of the left handed and right handed connectors would be swapped.

[0081] In FIG. 3, each screen assembly 4 comprises two screen element fixation parts 14 to fixate each end of the tubular screen element 7 to the base pipe section 3. Furthermore, the well tubular structure 2 has an opening 23 for letting the fluid into the well tubular structure. The completion system further comprises a flow section 15 mounted as part of the well tubular structure for allowing fluid to flow into or out of the well tubular structure through the opening 23 in the flow section 15 for letting fluid from the screen assemblies into the well tubular structure. The flow section is mounted between two screen assemblies so that the first screen assembly 4, 4a and second screen assembly 4, 4b are mounted on one side of the flow section, and a third screen assembly 4, 4c and a fourth screen assembly 4, 4d are mounted on the other side of the flow section 15. The flow section 15 has a first end 16 mounted to the second screen assembly 4, 4b and a second end 17 mounted to the third screen assembly 4, 4c.

[0082] The completion system 1 shown in FIG. 3 further comprises a second tubular member 18 arranged opposite the flow section 15, so that fluid flowing in through the tubular screen element of one of the screen assemblies 4, 4a, 4b, 4c, 4d flows on the outside of the base pipe section 3 and in through the flow section 15, or vice versa, in the event that fluid, e.g. fracturing fluid, cleaning fluid or acid, flows from the base pipe section through the opening 23 and out through the screen assemblies. The completion system 1 further comprises two annular barrier assemblies 30. Each annular barrier assembly 30 comprises a base pipe section 3 for being mounted as part of the well tubular structure 2 and the base pipe section comprises an aperture 31 for letting fluid therethrough to expand the annular barrier assembly. Each annular barrier assembly 30 further comprises an expandable sleeve 32 surrounding the base pipe section 3 and having an inner face 33 facing the base pipe section 3 and an outer face 34 facing a wall 35 of a borehole 36. Each end 37 of the expandable sleeve 32 is connected with the base pipe section 3, forming an annular space 38 between the inner face of the expandable sleeve 32 and the base pipe section 3.

[0083] As shown in FIG. 3, the annular barrier assembly 30 further comprises an anti-collapse unit 43, so that after expansion the fluid connection between the aperture 31 and the annular space 38 is closed, and a fluid connection between the annular space and the borehole is opened. The fluid connection to the borehole may further run through the adjacent screen assembly 4.

[0084] In FIG. 4, the flow section 15 comprises a sliding sleeve 41 for covering the opening 23. The flow section has a groove 26 in which the sliding sleeve 41 slides without decreasing the inner diameter of the base pipe section. The second tubular member 18 comprises radially extending projection parts 22 to ensure that there is always a distance, so that the fluid can flow to the opening 23 even though the pressure in the borehole is higher than the pressure in the annular space 27. The projection part may be a dimple.

[0085] The completion system may further comprise centralisers 25 for centralising the well tubular structure when the structure is run in the borehole, as shown in FIG. 5. The centralisers 25 are arranged close to the screen assemblies to protect them while the well tubular structure is run in hole. The centralisers ensure a certain distance from the well tubular structure to the wall of the borehole, so that projections or ledges in the borehole wall do not harm the function of the screen assemblies while the screen assemblies pass down the borehole. In FIG. 5, the annular barrier assembly 30 is shown in its unexpanded position and is arranged between the centraliser and one of the screen assemblies. The tubular member connector 12 could also be a centraliser, besides functioning as a tubular member connector. Even though not shown in FIG. 5, the completion system does not necessarily have the second tubular member 18 arranged opposite the flow section 15, but merely to one side if screen assemblies are only arranged at the one side.

[0086] In FIG. 6, the flow section 15 comprises two sliding sleeves 41, a first sliding sleeve 41, 41a for covering a first opening 23, 23a and a second sliding sleeve 41, 41b for covering a second opening 23, 23b through which fluid for fracturing the formation or another fluid for treating the formation can flow. The flow section 15 further comprises a flow section connector 15b to connect to another base pipe. Thus, the sliding sleeves 41, 41a, 41b are slid into the groove 26 of the flow section 15 and then the flow section connector 15b is connected so that the sliding sleeves are restricted to slide in the groove 26.

[0087] The first tubular members opposite the assembly connection parts 8 may also comprise at least one radially extending projection part to ensure the distance D shown in FIG. 2.

[0088] The completion system may further comprise a third tubular member 7 for connecting the screen element fixation part to a connection part 39 of the annular barrier assembly.

[0089] Furthermore, the tubular member may comprise a screen 42, shown in FIG. 4. And in another embodiment, one of the base pipe sections 3 may have an opening 23 for letting the fluid into the well tubular structure.

[0090] When completing the well, the base pipe sections 3 of the first screen assembly 4, 4a and second screen assembly 4, 4b are mounted by means of an assembly connection part 8 or directly without the assembly connection part 8 in case of integral flush joints or upset connections, then the first tubular member 11 is slid along the tubular screen element 7 of the first screen assembly and positioned opposite and over the assembly connection part. Thus sufficient space is left on the base pipe/casing for clamping of the base pipe using conventional rig equipment. Then the first tubular member connector 12, 12a is slid along the tubular screen element 7 of the first screen assembly 4, 4a, and the second tubular member connector 12, 12b is slid along the tubular screen element 7 of the second screen assembly 4, 4b, and both tubular member connectors are threadingly engaging external threads on the screen element fixation parts 14, thereby fastening the tubular member therebetween. Subsequently, a flow section 15 is mounted as part of the well tubular structure by connecting the flow section 15 to an end of a base pipe section 3 of one of the screen assemblies. Then further screen assemblies may be mounted as part of the well tubular structure 2 before an annular barrier assembly is mounted as part of the well tubular structure 2 to isolate a first zone of the borehole from a second zone of the borehole. An annular barrier assembly may be mounted in each end of the section comprising the screen assemblies and the flow section to isolate the zone of the borehole opposite the screen assemblies. By having several assemblies mounted together, a greater inflow area is created, and if one of the screen assemblies is blocked, the fluid from the reservoir can flow in through other screen assemblies in the same production zone. By having only one flow section through which the fluid can flow into the well tubular structure, the zone can easily be shut off if the zone starts producing too much water.

[0091] The second tubular member is mounted in the same way as the first tubular member and is thus slid along the tubular screen element of the second or third screen assembly, positioning the second tubular member opposite and over the flow section, and is fastened by tubular member connector 12 which is also slid along the tubular screen element 7.

[0092] When the completion system is mounted and run in hole, production is initiated by letting fluid in through the first screen assembly 4,4a of a completion system and past the annular space 24 between the first tubular member 11 and an assembly connection part 8. Then the fluid flows between the tubular screen element 7 and the base pipe section 3 of the second screen assembly 4, 4b and into the annular space 27 under the second tubular element 18 and into the flow section 15 and in through the opening 23 into the well tubular structure. The fluid let in through the first screen assembly may also flow directly into the annular space 27 opposite the flow section.

[0093] By fluid or well fluid is meant any kind of fluid that may be present in oil or gas wells downhole, such as natural gas, oil, oil mud, crude oil, water, etc. By gas is meant any kind of gas composition present in a well, completion, or open hole, and by oil is meant any kind of oil composition, such as crude oil, an oil-containing fluid, etc. Gas, oil, and water fluids may thus all comprise other elements or substances than gas, oil, and/or water, respectively.

[0094] By a well tubular structure, a casing or production casing is meant any kind of pipe, tubing, tubular, liner, string etc. used downhole in relation to oil or natural gas production.

[0095] Although the invention has been described in the above in connection with preferred embodiments of the invention, it will be evident for a person skilled in the art that several modifications are conceivable without departing from the invention as defined by the following claims.