This specification discloses a method for the production of subaqueous deposits of fluid minerals through a subsea satellite system. The wells are drilled in a circular pattern through a template on the marine bottom serving also as base upon which the satellite body is installed. The production and control passages of each of the wells are connected to production equipment within the satellite body by separate connector units, independently lowered into place from a surface vessel, to form portions of fluid paths between the passages within the subsea wellheads and the production equipment within the shell of the satellite. Such an installation permits production through the satellite, installed on the template base, after only one of the wells has been drilled and completed. 2 Claims, No Drawings

Current U.S. Class:	166/366 ; 166/356; 166/368
Current International Class:	B63G 8/00 (20060101); E21B 33/03 (20060101); E21B 33/035 (20060101); E21B 43/017 (20060101); E21B 43/00 (20060101); E21b 007/12 (); E21b 033/035 ()
Field of Search:	175/8,9 166/.5,.6

William J. Scherback Frederick E. Dumoulin Alan G. Paul Donald L. Dickerson Sidney A. Johnson

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Claims

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1. A method for exploiting subaqueous deposits of fluid minerals through a subsea production station, including the following steps: a. setting a base template, through which wells are to be drilled, on a marine bottom beneath the surface of a body of water; b. drilling at least one well through said base template; c. completing said at least one well with a subsea wellhead supported on said base template; d. releasably installing a production satellite body beneath the surface of said body of water on said base template; e. subsequent to step (d), fluidly connecting said at least one completed well with production facilities through said production satellite body by means of a substantially rigid connector unit releasably connected between said at least one subsea wellhead supported on said base template and said production satellite body installed on said base template; f. subsequent to connecting said at least one completed well with production facilities through said production satellite body, drilling at least one more well through said base template; g. completing said at least one more well with a subsea wellhead supported on said base template; and h. fluidly connecting said at least one more completed well with said production facilities through said subsea production satellite body by means of a substantially rigid connector unit releasably connected between said at least one more subsea wellhead supported on said base template and said production satellite body releasably installed on said base template.

2. A method for exploiting subaqueous deposits of fluid minerals through a subsea satellite station, as recited in claim 1, wherein said at least one well is drilled and completed, and said production satellite body is installed, substantially from a floating station.

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Description

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This invention relates to a method involving a subsea satellite designed to be independently connected to a number of surrounding subsea wellheads and to control the production therefrom, the subaqueous wells being produced through the subsea satellite wherein the produced fluids are separated, metered, and from which they are transported to a storage facility. More particularly, the invention relates to a method utilizing a simplified means for connecting a satellite separately to a plurality of closely surrounding subsea wellheads.

2. Description of the prior Art

Since its inception, the offshore oil and gas industry has used bottom-supported above-surface platforms as the principal mechanism for the installation and support of the equipment and services necessary for the production of the subaqueous mineral deposits. As the industry has developed over the years, it has extended its search for offshore minerals from its birthplace, producing oil and gas in the shallow coastal waters off California and the Gulf of Mexico into areas where, because of excessive water depth and/or other local conditions, the bottom-supported platform is not as economically or technologically feasible.

A possible solution is to install the production facilities on a floating platform, as is described in the H. D. Cox U.S. Pat. No. 3,111,692, issued Nov. 26, 1963, which can be maintained in position in a field by either a fixed multipoint mooring system of anchors and anchor lines, or by a dynamic positioning system. The above solution involves the expense of continuous maintenance and surveillance of the locating system as well as the associated problems and expense of maintaining the multiple flexible lines connecting wellheads on the marine bottom with the continuously moving floating production platform, and the potential hazard, of this system, to the hoses, in the event of a failure to the fixed mooring or dynamic positioning systems. In areas where there is extremely deep water and/or adverse surface conditions, a fully subsea installation may be the most advisable solution. One method, as is shown by the J. A. Haeber U.S. Pat. No. 3,261,398, issued Jul. 19, 1966, is to locate the individual pieces of production equipment on the marine bottom. Such an installation almost necessitates the use of robots such as shown in the G. D. Johnson U.S. Pat. No. 3,099,316, issued Jul. 30, 1963. However, such instrumentalities are expensive and not without their own limitations and maintenance problems.

Another solution is disclosed in the William F. Manning Pat. application Ser. No. 663,799, entitled "Subsea Satellite Foundation Unit and Method for Installing a Satellite Body within said Foundation Unit," filed Aug. 28, 1967. A template is first set on the marine bottom and the wells are drilled through the template. The Satellite is then set in the template, surrounded closely by the subsea wellheads. However, the satellite cannot be installed until all of the wells are completed. For purposes of economy, the satellite should be installed as soon as the first well is drilled and completed. Therefore, means must be devised for attaching each well independently to the satellite body. This is also desirable from the point of view of ease of registry of the satellite body with the wellheads.

In accordance with the present invention, a subsea satellite body can be installed on a base template on a marine bottom prior to the completion of any producing wells therethrough. Each well when completed produces through upstanding tubing nipples extending from the upper ends of the subsea wellheads mounted on the well conductor pipes forming a portion of the base template. Complementary upstanding tubing nipples extend upwardly from the upper end of the satellite body. When a particular well is completed, a stab-over connector unit is lowered vertically through the body of water, one end thereof stabbing over the tubing nipples extending upwardly from the subsea wellhead and the other end stabbing down over the vertical tubing nipples extending upwardly from the upper end of the satellite body.

FIG. 1 is a pictorial view of a subsea production system in accordance with the present invention; and FIG. 2 is a schematic diagram of a satellite station configuration for allowing the satellite body to be installed on a base template of a satellite station prior to the completion of any of the wells through the base template.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Now looking to FIG. 1, a subsea system for producing fluid minerals, in particular gas and oil, from a subaqueous field by a plurality of subsea wellheads is illustrated. A plurality of subsea production satellite stations, generally designated 10, are spaced across a marine bottom 12, each satellite station 10 comprising a satellite body 15 centrally positioned within a circular group of closely spaced subsea wellheads 14. The produced fluids from the subaqueous wells are directed through encircling subsea wellheads 14 into the satellite body 15 of the respective satellite station 10. The fluids being produced from the subsea wellheads 14 of each circular group are combined within the respective enclosed satellite body 15 and a first stage of separation (gravity) takes place. At least the liquid portion is then directed to a circular manifold 16 atop a central bottom-mounted storage tank 17 through a shipping line 18, one shipping line 18 extending from each satellite station 10.

A floating master station 20, having power-generating and final stage separation equipment thereon, as well as being fitted out with off-loading apparatus, is in fluid and electrical communication with the bottom-supported storage tank 17 through a tensioned tether pipe 22 extending from the storage tank 17 to a point just beneath the turbulent surface zone of the body of water and fixed at this point to a large subsurface buoy 24. A flexible conduit 26, containing a plurality of electrical and fluid flow paths, extends from the upper end of the tensioned tether pipe 22 to the floating master station 20. The produced liquid, collected in the circular manifold 16, is directed to the master station through a main shipping line 27 supported along the length of the tether pipe 22, and a fluid line forming a portion of the flexible conduit 26. The produced liquid passes through the final stage separation equipment on the master station 20 where the pressure is normalized and dissolved gases are removed. The dead liquid is then transported to storage within the storage tank 17 through a line of the flexible conduit 26 connected to an axial passage in the interior of the tether pipe 22.

In the upper left-hand corner of FIG. 1 is illustrated the drilling of a well through a satellite base template, generally designated 28, which has been previously installed on a marine bottom along with a shipping line 18 for connecting a satellite station, when completed in conjunction with the template 28, with the storage tank 17. A drill string 30 is suspended from above the surface from a semisubmersible drilling vessel 32 and extends through a blowout preventer stack 33 mounted on one of a plurality of upstanding well conductor pipes 34 forming a portion of the template 28. Illustrated in the lower portion of FIG. 1 is a manned submersible work vehicle, generally designated 36, of a type to be employed to assist in the subsea operations and for the dry transfer of personnel to the satellite station 10. The submersible work vehicle 36 has a pair of articulated arms 38 and 40 carrying a socket wrench 42 and a vise grip tool 44, respectively. The submersible work vehicle 36 is further equipped with a pivotable positioning motor 46 on each side (one shown) to assist in locating the submersible work vehicle 36 adjacent a satellite station 10 firstly when subsea operations are to be performed during the drilling operations and the installation of the satellite body 15 therewithin, and at later times during maintenance and workover operations. A lower port 48 of the submersible work vehicle 36 is connected with a rear compartment (not shown) within the shell thereof to permit a diver to be released at an installation site if one should be needed. The rear compartment is isolated from the pilot's compartment, seen through the front view plate 50, so that a diver after exposure to deep water can be kept in compression in the rear compartment while the front compartment is maintained at atmospheric conditions. This general type of submersible work vehicle is well-known in the art and specific vehicles of this type are more fully described in the application Ser. No. 649,959, filed Jun. 29, 1967, of Warren B. Brooks, Charles Ovid Baker, and Eugene L. Jones, and the references cited therein.

FIG. 2 illustrates a satellite station 10 which is capable of being installed prior to completing any of the production wells through the ring 51 of the base template 28. The satellite body is held in the satellite base 28 by a central sleeve 250 depending from the lower end of the satellite body 15 and automatic spring-loaded latches (not shown) over the upper end of the well conductor pipe of the water well 52. The latches can be disabled by a hydraulic pressure applied through the conduit 252 extending between a manifold 254, forming a portion of the framing of the base template 28, at the inner end, and a quick-disconnect coupling section 256, at the outer end. The outer end of the conduit is supported by a skeletal frame 258 to displace the coupling section 256 outward of the well conductor pipes 34. The arrangement of the equipment within the satellite body 15 is described in detail in copending U.S. application, Ser. No. 740,783, filed Jun. 27, 1968. The connector units 54 are not permanently attached to the satellite body 15 but instead are stabbed-over tubing nipples 260 extending vertically out of the upper end of the satellite body 15. When a well is to be completed through one of the upstanding well conductor pipes 34, a wellhead 14 is first mounted on the respective well conductor pipe 34. A connector unit 54 is later lowered from the surface to make the connection between the wellhead 14 and the satellite body 15. The connector unit 54 consists of a curved tubing section 56 and a vertical lubricator section 58. The lower end of the lubricator section 58 is stabbed over the tubing (not shown) extending vertically out of the upper end of the wellhead 14, while the outer vertical free ends of the curved tubing section 54 stabs over the respective ones of the upstanding tubing nipples 260 extending out of the upper end of the satellite body 15. In this manner, with each connector section 54 being individually engaged between the wellhead 14 and the respective upstanding tubing nipples 260, greater tolerances can be allowed in installing the satellite body 15. Furthermore, an individual well can be produced through the satellite station 10 while the remaining wells are still being drilled and completed. The vertical orientation of the tubing nipples 260 extending vertically into the satellite body 15 presents no problem, each of the TFL storage chambers 146 is reoriented into a vertical position so as to be coaxial with the respective tubing nipples 260. The vertical position of the storage chamber 146 permits the TFL tool 126 stored therewithin to move easily into respective tubing nipples 260 so that it can be pumped, under fluid pressure, through a full 180.degree. bend in the tubing sections 56 of the connector unit 54. Such a bend, of 180.degree., will not present any insurmountable problems requiring only that the wells be spaced out far enough from the satellite body 15 to obtain a 5 foot radius bend in the conduit. Stab-over connections, as discussed in this application, are more fully described in the Manning application Ser. No. 663,799.

Although the present invention has been described in connection with details of the specific embodiments thereof, it is to be understood that such details are not intended to limit the scope of the invention. The terms and expressions employed are used in a descriptive and not a limiting sense and there is no intention of excluding such equivalents in the invention described as fall within the scope of the claims. Now having described the apparatus and methods herein disclosed, reference should be had to the claims which follow.

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