AU2007299803A1

AU2007299803A1 - Systems and methods for drilling and producing subsea fields

Info

Publication number: AU2007299803A1
Application number: AU2007299803A
Authority: AU
Inventors: Walter Edward Schott III; Adrian Paul Williams
Original assignee: SHELL INT RESEARCH; Shell Internationale Research Maatschappij BV
Current assignee: Shell Internationale Research Maatschappij BV
Priority date: 2006-09-21
Filing date: 2007-09-19
Publication date: 2008-03-27
Anticipated expiration: 2027-09-19
Also published as: WO2008036740A3; GB2455426B; GB2455426A; BRPI0716922A2; CN101517188B; WO2008036740A2; MY183925A; AU2007299803B2; US20090314495A1; CN101517188A; GB0902195D0; NO20091567L

Description

WO 2008/036740 PCT/US2007/078892 SYSTEMS AND METHODS FOR DRILLING AND PRODUCING SUBSEA FIELDS Field of Invention There are disclosed systems and methods for drilling and producing subsea fields. 5 Background As the current trend in offshore oil and gas production advances into deeper waters, and the oil and gas prices remain depressed, it is becoming increasingly necessary for the industry to develop cost effective solutions to develop small fields in deep waters. A typical solution for such cases is to keep the production facilities on a "host 10 platform" and connect the deep-water well(s) to the platform with pipelines and risers. The host platform may be able to perform some direct vertical access (DVA) drilling for a field directly below the platform. Additional drilling for adjacent surrounding fields is accomplished with mobile offshore drilling units, such as a drill ship, semi-submersible, or jack-up rig. Production from the surrounding wells is produced to a subsea tree, then 15 multiple wells collected at a manifold, and the combined production piped to the production facilities. The supporting equipment for the subsea tree control, such as hydraulic and electric power units, chemical injection pumps and tanks, and a control console, may be housed on the host platform. The subsea tree control may be accomplished via long umbilical(s) consisting of electric conductors, hydraulic lines and 20 chemical injection lines laid alongside the pipeline. The cost and technical challenges of a conventional drilling and production system may increase as the tieback distance increases, and as the water depth increases. Referring now to Figure 1, there is illustrated a prior art conventional subsea drilling and production system. System 100 is located in body of water 104 having bottom 25 108. Production host 102 is at a fixed location in body of water 104. Well group 130 includes wells 110, 112, 114, and 116 connected to manifold 106 by jumpers. Manifold is connected to production host 102 by riser 107. Production host 102 may perform various processes on produced fluids and gases before sending the products to another location by outlet 120 which may be used to feed a pipeline or load a vessel for transportation of the 30 products. The processes may include one or more of separating oil, water, and gases; electrical, chemical, and/or heat treating; breaking emulsions; removing undesirable components from the streams; re-injecting water or other components into one or more of the wells; and/or other processes as are known in the art. 1 WO 2008/036740 PCT/US2007/078892 Sometimes, production host 102 may be used to drill well group 130 for which it has direct vertical access. Other times, mobile offshore drilling unit 302 may be used to drill well group 130. In all cases, mobile offshore drilling unit 302 is needed to drill adjacent well groups 230 and 330 for which production host 102 does not have access. For 5 system 100, production host 102 is a permanent part of the system, and mobile offshore drilling unit 302 is brought in whenever one or more wells are needed to be drilled. As illustrated, mobile offshore drilling unit 302 is drilling new well 314. Riser 307 is connecting mobile offshore drilling unit 302 to wellhead of well 314, which may include a subsea blow out preventer, and/or other subsea wellhead devices as are known in the art. 10 Well group 230 includes wells 210, 212, 214, and 216 connected to manifold 206. Manifold 206 is connected to production host 102 by riser 107, manifold 106, and flowline 220. Well group 330 includes wells 310 and 312 connected to manifold 306. Manifold 306 is connected to production host 102 by riser 107, manifold 106, and flowline 320. Alternatively, manifold 306 may be connected to manifold 206, which may then be 15 connected to manifold 106. U.S. Patent Number 6,752,214 discloses a system for producing hydrocarbons from a subsea well including an unmanned floating platform positioned over the well, the platform including equipment for inserting coiled tubing or wireline tools or the like into the well for servicing, controlling, or conducting other operations in or to the well, a 20 vertical access riser connecting the platform to the well, a control umbilical connecting the platform to the well, a host facility adapted to receive the produced hydrocarbons, and a production pipeline connecting the well to the host facility, the production pipeline including at least one access port between the well and the host facility. U.S. Patent Number 6,752,214 is herein incorporated by reference in its entirety. 25 There is a need in the art for improved systems and methods for drilling and producing a plurality of adjacent oil and/or gas containing subsea fields. There is another need in the art for more efficient systems and methods for drilling and producing a plurality of adjacent oil and/or gas containing subsea fields from a single drilling and production vessel. 30 There is another need in the art for more efficient systems and methods for drilling and producing a plurality of adjacent oil and/or gas containing subsea fields from a mobile drilling and production vessel. 2 WO 2008/036740 PCT/US2007/078892 These and other needs of the present disclosure will become apparent to those of skill in the art upon review of this specification, including its drawings and claims. Summary of the Invention One aspect of the disclosed invention provides a system comprising a mobile 5 offshore drilling unit, a first group of wells drilled by the mobile offshore drilling unit, a second group of wells drilled by the mobile offshore drilling unit, wherein the mobile offshore drilling unit comprises processing equipment adapted to process production from the first group of wells and the second group of wells. Another aspect of the disclosed invention provides a method of drilling and 10 producing subsea fields comprising drilling a first group of wells with a mobile offshore drilling unit, connecting the first group of wells together with a first manifold, drilling a second group of wells with the mobile offshore drilling unit, connecting the second group of wells together with a second manifold, connecting the first manifold to the second manifold with a flow line, connecting at least one of the first manifold and the second 15 manifold to the mobile offshore drilling unit with a flow line, and processing production from the first group of wells and the second group of wells with the mobile offshore drilling unit. Advantages of the invention include one or more of the following: Improved systems and methods for drilling and producing a plurality of adjacent oil 20 and/or gas containing subsea fields. Improved systems and methods for drilling and producing a plurality of adjacent oil and/or gas containing subsea fields from a single drilling and production vessel. Improved systems and methods for drilling and producing a plurality of adjacent oil and/or gas containing subsea fields from a mobile drilling and production vessel. 25 Brief Description of the Drawings Figure 1 illustrates a drilling and production system. Figure 2a illustrates a drilling and production system. Figure 2b illustrates a drilling and production system. Figure 2c illustrates a drilling and production system. 30 Figure 2d illustrates a drilling and production system. Figure 3 illustrates a drilling and production system. 3 WO 2008/036740 PCT/US2007/078892 Figure 4 illustrates a drilling and production system. Figures 5a-5f illustrate the installation of a drilling and production system. Figures 6a-6c illustrate the expansion of a well and manifold system. Detailed Description of the Invention 5 In one embodiment of the invention, there is provided a system comprising a mobile offshore drilling unit, a first group of wells drilled by the mobile offshore drilling unit, a second group of wells drilled by the mobile offshore drilling unit, wherein the mobile offshore drilling unit comprises processing equipment adapted to process production from the first group of wells and the second group of wells. In some 10 embodiments, the system also includes a first manifold adapted to collect production from the first group of wells. In some embodiments, the system also includes a second manifold adapted to collect production from the second group of wells. In some embodiments, the first manifold is connected to the second manifold by a flow line. In some embodiments, the mobile offshore drilling unit is floating. In some embodiments, the system also 15 includes a gas and a liquid export line connected to the mobile offshore drilling unit. In some embodiments, the system also includes a third group of wells drilled by the mobile offshore drilling unit. In one embodiment of the invention, there is provided a method of drilling and producing subsea fields comprising drilling a first group of wells with a mobile offshore 20 drilling unit, connecting the first group of wells together with a first manifold, drilling a second group of wells with the mobile offshore drilling unit, connecting the second group of wells together with a second manifold, connecting the first manifold to the second manifold with a flow line, connecting at least one of the first manifold and the second manifold to the mobile offshore drilling unit with a flow line, and processing production 25 from the first group of wells and the second group of wells with the mobile offshore drilling unit. In some embodiments, the method also includes drilling a third group of wells with the mobile offshore drilling unit and connecting the third group of wells together with a third manifold. Referring now to Figure 2a, there is illustrated subsea drilling and production 30 system 400. System 400 is located in body of water 404 having bottom 408. Combined drilling and production vessel 402 is at a first location in body of water 404. Well group 430 includes wells 410, 412, 414, and 416 connected to manifold 406 by jumpers. Manifold is connected to drilling and production vessel 402 by flowline 432. 4 WO 2008/036740 PCT/US2007/078892 Drilling and production vessel 402 is drilling well 416. Drilling and production vessel 402 is connected to well 416 by riser 407. Well 416 may include a wellhead, a casing/liner hanger, a subsea blow out preventer, and/or other subsea wellhead devices as are known in the art. 5 Drilling and production vessel 402 may perform various processes on produced fluids and gases from well group 430 before sending the products to another location by outlet 420 which may be used to feed a pipeline or load a vessel for transportation of the products. The processes may include one or more of separating oil, water, and gases; electrical, chemical, and/or heat treating; breaking emulsions; removing undesirable 10 components from the streams; re-injecting water or other components into one or more of the wells; and/or other processes as are known in the art. Drilling and production vessel 402 is being used to drill well group 430 for which it has direct vertical access, as well as processing production from well group 430. Referring now to Figure 2b, there is illustrated subsea drilling and production 15 system 400 drilling well group 530. Drilling and production vessel 402 has been moved from the location in Figure 2a, and is now being used to drill well group 530 for which it has direct vertical access, as well as processing production from well group 430 and well group 530. Production from well group 430 wells 410, 412, 414, and 416 are collected at 20 manifold 406 and sent by flowline 433 to manifold 506. Production from well group 530 wells 510, 512, 514, and 516 are also collected at manifold 506. Production from well group 430 and well group 530 are sent by flowline 532 from manifold 506 to drilling and production vessel 402. Drilling and production vessel 402 is drilling well 516. Drilling and production 25 vessel 402 is connected to well 516 by riser 407. Well 516 may include a wellhead, a casing/liner hanger, a subsea blow out preventer, and/or other subsea wellhead devices as are known in the art. Referring now to Figure 2c, there is illustrated subsea drilling and production system 400 drilling well group 630. Drilling and production vessel 402 has been moved 30 from the locations in Figures 2a and 2b, and is now being used to drill well group 630 for which it has direct vertical access, as well as processing production from well group 430, well group 530, and well group 630. 5 WO 2008/036740 PCT/US2007/078892 Production from well group 430 wells 410, 412, 414, and 416 are collected at manifold 406 and sent by flowline 433 to manifold 506. Production from well group 530 wells 510, 512, 514, and 516 are collected at manifold 506. Production from well group 430 and well group 530 are sent by flowline 533 from manifold 506 to manifold 606. 5 Production from well group 630 wells 610, 612, and 614 are collected at manifold 606. Production from well group 430, well group 530, and well group 630 are sent by flowline 632 from manifold 606 to drilling and production vessel 402. Drilling and production vessel 402 is drilling well 614. Drilling and production vessel 402 is connected to well 614 by riser 407. Well 614 may include a wellhead, a 10 casing/liner hanger, a subsea blow out preventer, and/or other subsea wellhead devices as are known in the art. In some embodiments, other well groups may be drilled with drilling and production vessel 402, connected to a manifold, and all the well groups' manifolds connected by one or more flowlines, and then sending the production from all of the well 15 groups to the drilling and production vessel 402 for processing and export. Referring now to Figure 2d, in some embodiments, there is illustrated subsea drilling and production system 400 reworking well 414 in well group 430. Drilling and production vessel 402 has been moved from the locations in Figures 2b and 2c, and is now being used to rework well 414 in well group 430 for which it has direct vertical access 20 and/or drill additional wells in well group 430 (not shown), as well as processing production from well group 430, well group 530, and well group 630. Production from well group 630 wells 610, 612, and 614 are collected at manifold 606 and sent by flowline 533 to manifold 506. Production from well group 530 wells 510, 512, 514, and 516 are collected at manifold 506. Production from well group 630 and well 25 group 530 are sent by flowline 433 from manifold 506 to manifold 406. Production from well group 430 wells 410, 412, 414, and 416 are collected at manifold 406. Production from well group 430, well group 530, and well group 630 are sent by flowline 432 from manifold 406 to drilling and production vessel 402. Drilling and production vessel 402 is drilling well 414. Drilling and production 30 vessel 402 is connected to well 414 by riser 407. Well 414 may include a wellhead, a casing/liner hanger, a subsea blow out preventer, and/or other subsea wellhead devices as are known in the art. 6 WO 2008/036740 PCT/US2007/078892 Referring now to Figure 3, in some embodiments, there is illustrated subsea drilling and production system 500 processing oil and/or gas production from drilling centers 1-4: DCl, DC2, DC3, and DC4. Host 502 is anchored at DC4. Host 502 may be used to drill additional wells in 5 DC4. DC4 has subsea system 546d. Production from wells in DC4 goes to manifold 506d. Manifold 506d may be controlled from host 502 by umbilical 544d. Production then goes from subsea system 546d to host by flowline 532d through vertical portion to buoyant connectors 540d, then through flexible portion to host 502. Host 502 processes the production into finished oil and finished gas. Oil is sent back to subsea system 546d by 10 way of a different flexible portion to buoyant connectors 540d, through vertical portion, and to subsea system 546d. At subsea system 546d, oil is put in oil export line 420a. Gas is likewise sent from host 502 to subsea system 546d, and put in gas export line 420b. DC3 has subsea system 546c. Production from wells in DC3 goes to manifold 506c. Manifold 506c may be controlled from host 502 by umbilical 544c, which is 15 connected to umbilical 542c at buoyant connectors 540c. Production then goes from subsea system 546c by flowline 533c to subsea system 546d, then to host by flowline 532d through vertical portion to buoyant connectors 540d, then through flexible portion to host 502. Host 502 processes the production into finished oil and finished gas. Oil is sent back to subsea system 546d by way of a different flexible portion to buoyant connectors 540d, 20 through vertical portion, and to subsea system 546d. At subsea system 546d, oil is put in oil export line 420a. Gas is likewise sent from host 502 to subsea system 546cd and put in gas export line 420b. DC1 has subsea system 546a. Production from wells in DC1 goes to manifold 506a. Manifold 506a may be controlled from host 502 by umbilical 544a, which is 25 connected to umbilical 542a at buoyant connectors 540a. Production then goes from subsea system 546a by flowline 533a to subsea system 546c, then by flowline 533c to subsea system 546d, then to host by flowline 532d through vertical portion to buoyant connectors 540d, then through flexible portion to host 502. Host 502 processes the production into finished oil and finished gas. Oil is sent back to subsea system 546d by 30 way of a different flexible portion to buoyant connectors 540d, through vertical portion, and to subsea system 546d. At subsea system 546d, oil is put in oil export line 420a. Gas is likewise sent from host 502 to subsea system 546d, and put in gas export line 420b. 7 WO 2008/036740 PCT/US2007/078892 DC2 has subsea system 546b. Production from wells in DC2 goes to manifold 506b. Manifold 506b may be controlled from host 502 by umbilical 544b, which is connected to umbilical 542b at buoyant connectors 540b. Production then goes from subsea system 546b by flowline 533b to subsea system 546a, then by flowline 533a to 5 subsea system 546c, then by flowline 533c to subsea system 546d, then to host by flowline 532d through vertical portion to buoyant connectors 540d, then through flexible portion to host 502. Host 502 processes the production into finished oil and finished gas. Oil is sent back to subsea system 546d by way of a different flexible portion to buoyant connectors 540d, through vertical portion, and to subsea system 546d. At subsea system 546d, oil is 10 put in oil export line 420a. Gas is likewise sent from host 502 to subsea system 546d, and put in gas export line 420b. Referring now to Figure 4, in some embodiments, there is illustrated subsea drilling and production system processing oil and/or gas production from drilling centers 1-4: DC1, DC2, DC3, and DC4. Host 502 is located at DC4. 15 DC2 has a number of wells producing to a manifold, which collects the production to be placed in a flowline, which flows to DC1. DC1 has a number of wells producing to a manifold, which collects the production to be placed in a flowline along with the production from DC2, which flows to DC3. DC3 has a number of wells producing to a manifold, which collects the production to be placed in a flowline along with the 20 production from DC1 and DC2, which flows to DC4. DC4 has a number of wells producing to a manifold, which collects the production to be placed in a flowline along with the production from DC1, DC2, and DC3 which flows to host 502 to be processed. Referring now to Figures 5a-5f, in some embodiments, there is illustrated one suitable installation for subsea drilling and production system 500 with drilling centers 1-4: 25 DC1, DC2, DC3, and DC4. In Figure 5a, DC1 is installed. DC1 has subsea system 546a. Buoyant connectors 540a are anchored at the sea floor, and connected to flow line 532a and other lines. Subsea system 546a may be controlled by umbilical 544a, which is connected to buoyant connectors 540a. Oil export line 420a and gas export line 420b are connected to subsea 30 system 546a to export processed oil and gas. In Figure 5b, host 502 is installed above DC1 with the use of tethers, anchors, and/or thrusters. Flow line 532a and other lines are connected from buoyant connectors 540a to host 502. 8 WO 2008/036740 PCT/US2007/078892 In Figure 5c, DC2 is installed. DC2 has subsea system 546b. Buoyant connectors 540b are anchored at the sea floor, and connected to flow line 532b and other lines. Subsea system 546b may be controlled by umbilical 544b, which is connected to buoyant connectors 540b. Oil export line 420a and gas export line 420b are connected to subsea 5 system 546b to export processed oil and gas. Flow line 533b is used to flow production from subsea system 546b to subsea system 546a, and then to host 502 by flow line 532a. Host 502 has been used to drill subsea wells. Wells produce liquids and/or gases which are collected at 506a, and produced to subsea system 546a and to the surface by flowline 532a. 10 In Figure 5d, host 502 is installed above DC2 with the use of tethers, anchors, and/or thrusters. Flow line 532b and other lines are connected from buoyant connectors 540a to host 502. In Figure Se, DC3 is installed. DC3 has subsea system 546c. Buoyant connectors 540c are anchored at the sea floor, and connected to flow line 532c and other lines. Subsea 15 system 546c may be controlled by umbilical 544c, which is connected to buoyant connectors 540c. Oil export line 420a and gas export line 420b are connected to subsea system 546c to export processed oil and gas. Flow line 533a is used to flow production from subsea system 546c to subsea system 546a, to subsea system 546b by flowline 533b, and then to host 502 by flow line 532b. 20 In Figure 5f, the installation of the system has been completed. Host 502 has been moved to DC4, where it may be used to drill wells in DC4, and to process the productions from all of the drilling centers. It is also contemplated that more or fewer than four drilling centers may be installed, for example from about 2 to about 10, or from about 3 to about 6. In some embodiments, host 502 may be used to process production from a number 25 of drilling centers, and for drilling additional wells in a drilling center. In some embodiments, host 502 may be used to process production from a number of drilling centers, and for reworking wells in one drilling center. Referring now to Figures 6a-6c, in some embodiments, there is illustrated the expansion of a well and manifold system. 30 In Figure 6a, manifold 706a has been installed and connected to flow line 707. Wells 710, 712, 714, 716, 718, and 720 are drilled and connected to manifold 706a. 9 WO 2008/036740 PCT/US2007/078892 In Figure 6b, additional wells are drilled and connected to an additional manifold 706b. Manifold 706b has been installed and connected to manifold 706a. Wells 722, 724, 726, 728, 730, and 732 are drilled and connected to manifold 706b. In Figure 6c, additional wells are drilled and connected to an additional manifold 5 706c. Manifold 706c has been installed and connected to manifold 706b. Wells 734, 736, 738, 740, 742, and 744 are drilled and connected to manifold 706c. In some embodiments, additional wells and manifold may be installed as necessary to expand the field. Those of skill in the art will appreciate that many modifications and variations are 10 possible in terms of the disclosed embodiments, configurations, materials and methods without departing from their spirit and scope. Accordingly, the scope of the claims appended hereafter and their functional equivalents should not be limited by particular embodiments described and illustrated herein, as these are merely exemplary in nature. 10

Claims

1. A system for drilling and producing subsea fields, comprising: a mobile offshore drilling unit; 5 a first group of wells drilled by the mobile offshore drilling unit; a second group of wells drilled by the mobile offshore drilling unit; wherein the mobile offshore drilling unit comprises processing equipment adapted to process production from the first group of wells and the second group of wells . 10

2. The system of claim 1, further comprising a first manifold adapted to collect production from the first group of wells.

3. The system of one or more of claims 1-2, further comprising a second manifold adapted to collect production from the second group of wells. 15

4. The system of claims 2 and 3, wherein the first manifold is connected to the second manifold by a flow line.

5. The system of one or more of claims 1-4, wherein the mobile offshore drilling unit 20 is floating.

6. The system of one or more of claims 1-5, further comprising a gas and a liquid export line connected to the mobile offshore drilling unit. 25

7. The system of one or more of claims 1-6, further comprising a third group of wells drilled by the mobile offshore drilling unit. 11 WO 2008/036740 PCT/US2007/078892

8. A method of drilling and producing subsea fields comprising: drilling a first group of wells with a mobile offshore drilling unit; connecting the first group of wells together with a first manifold; 5 drilling a second group of wells with the mobile offshore drilling unit; connecting the second group of wells together with a second manifold; connecting the first manifold to the second manifold with a flow line; connecting at least one of the first manifold and the second manifold to the mobile offshore drilling unit with a flow line; and 10 processing production from the first group of wells and the second group of wells with the mobile offshore drilling unit.

9. The method of claim 8, further comprising drilling a third group of wells with the mobile offshore drilling unit and connecting the third group of wells together with a third 15 manifold. 12