Patent Publication Number: US-3877520-A

Title: Subsea completion and rework system for deep water oil wells

Description:
United States Patent [191 Putnam Apr. 15, 1975 Paul S. Putnam, 8931 La Entrada Ave., Apt. A, Whittier, Calif. 90605 [22] Filed: Aug. 17, 1973 [21] Appl. No.: 389,248  
 [76] Inventor:  
  52 us. C1 l66/.6; 166/75 51 1m.c1 E21b 33/035 [58] Field of Search 166/.5, .6, 75  
 [56] ileferences Cited UNITED STATES PATENTS 3,189,098 6/1965 Haeber l66/.6 3,308,880 3/1967 Yetman i l66/.5  
 3,332,484 7/1967 Watkins l66/.6  
 3,492,027 1/1970 Herring 166/.6  
 3,551,005 12/1970 Brun r 166/.5  
 3,633,667 l/1972 Falkner, Jr l66/.5 3,722,585 3/1973 Nelson et al l66/.6  
 Primary Examiner.lames A. Leppink Attorney, Agent, or FirmChristie, Parker &amp; Hale [57] ABSTRACT A subsea completion system for a plurality of wells drilled from a single template, the template being divided into a plurality of wellhead sections and a plurality of equipment sections. Each Wellhead section of the template has a concentric stab ring around the wellhead with the production and service tubing extending from the stab rings of the respective wellhead sections to similar stab rings in the equipment sections of the template. Well completion modules, header modules, separator modules, and power equipment modules are individually connected by means of a mating stab ring at the bottom of the modules to the respective stab rings in the template sections after the template is placed on the sea floor and the wells are drilled. Each well completion module includes the production tree, tubing, hydraulic controls, and equipment necessary to operate the well, the tubing and hydraulic lines terminating in the bottom stab ring for connection to the template. An upper stab ring is provided at the top of each module with tubing extending directly to the tubing connections in the lower stab ring through diverters. A multiposition diverter unit is attachable from the surface to the upper stab ring and can be operated to connect a riser to any one of the tubing connections in the stab ring, providing a direct tubing path between the riser and any one of the tubing connections in the corresponding section of the template. The direct tubing connection provides access for the setting or removal of plugs in the tubing in each template section from the surface through the associated module. This permits the tubing in the template to be shut off, permitting removal of any of the modules from the surface.  
 26 Claims, 13 Drawing Figures PATENTEDAPR 1 55975 SHEET 1. OF 5 saw 5 I 5 7&amp; 7  
 SUBSEA COMPLETION AND REWORK SYSTEM FOR DEEP WATER OIL WELLS FIELD OF THE INVENTION This invention relates to the operation of subsea oil and gas wells, and more particularly, is concerned with apparatus for completing and operating producing wells on the ocean floor entirely from the surface without the use of divers.  
 BACKGROUND OF THE INVENTION In recent years, the search for oil and gas reserves has been concentrated more and more in off-shore fields. This in turn has led to developments in techniques for drilling and completing wells in deeper and deeper waters. In typical operations, single exploratory wells may be drilled from a floating vessel. If significant reserves are located by the exploratory well, this well is usually plugged because the present cost of completing a single subsea well does not justify an attempted completion. At shallower depths, a permanent drilling platform is then erected from which typically 18 or wells can be drilled and completed. With the drilling platform, the wellhead is at the surface with all completion equipment being available on the platform. Thus the operation of the well is not substantially different from the operation of a well on land.  
  However, in the case of deep-water wells in 500 feet to over 1,000 feet of water depth, the building of a platform rising above the surface of the water becomes very costly if not completely impractical. This has given rise to a considerable effort in designing equipment for completing the wells on the ocean floor after they have been drilled from floating platforms. Various proposals have been made for handling production from subsea completed wells. Such systems usually require submerged manned supervision for repair and maintenance of equipment. The use of submarines, special diving bells, or other kinds of bubble-type life support system surrounding the wellhead have all been proposed but with obvious limitations. There have also been proposals for single well subsea completion systems which are designed to be installed and operated without the aid of divers or submersibles. See for example, the article Diverless Subsea Completion System for Deep-Water Oil Wells&#34; by C. B. Reeds and P. R. Seligman, Paper No. OTC 1594, Fourth Annual Offshore Technology Conference, May, 1972. However, such known systems have not been proved effective for a multiple well installation. Flowline connections are complicated by the horizontal position of the connections and remotely controlled valves are required to control fluid pressures during the connect and disconnect operation. No environmental control for the completion equipment is provided.  
 SUMMARY OF THE PRESENT INVENTION Thepresent invention is directed to equipment by which a multiple well installation can be completed on the ocean floor and in which all operation of the wells, including workover, equipment repair, water or gas injection, and other operating requirements of the wells during the life of the wells, can be carried out from the surface of the water. This is accomplished by providing a permanent base that serves as a drilling template for a plurality of wells. All equipment for operating the wells, including production trees, headers, separators, and power sources is arranged in modules that are removably attached to the template by stab connectors. All flow lines and hydraulic lines interconnecting the modules are mounted in the template but no valves or other moving parts are located in the template. Plugs can be set or removed from each of the flow lines in the template where they connect into any one of the modules. This can be done with the modules in place from the surface by means of a multiple diverter that con nects a riser through the top of a module to any one of the flow lines in the template, permitting a wire line to be passed from the surface directly into any selected one of the flow lines in the template. By setting plugs in the flow lines in the template, either by pumping the plugs down the flow lines or using a wire line tool, a module can be isolated from the rest of the system without the use of valves in the template so that it can be removed to the surface for repair or replacement.  
  The multiple diverter assembly can also be used to guide a module into position, the assembly then being returned to the surface. In this way, the different modules mounted on the template can share common vertical guide rods. The template includes only flow lines, hydraulic lines, and electrical cables. No active elements, such as switches, valves, pumps, or the like, are provided in the template. All connections to the template are made vertically so as to be easily carried out from the surface. All active equipment is mounted in enclosed modules that can be removed from the template by setting plugs from the surface in any associated lines in the template.  
 BRIEF DESCRIPTION OF THE DRAWINGS Fora more complete understanding of the present invention, reference should be made to the accompanying drawings, wherein:  
  FIG. 1 is an isometric view of a sub-sea wellhead installation according to the present invention;  
  FIG. 2 is a sectional view of a wellhead completion module;  
  FIG. 3 is a top view of the wellhead completion module;  
  FIG. 4 is a top view of a stab ring assembly in the template;  
  FIG. 5 is an enlarged detail drawing of the area shown within the circled line 5 of FIG. 2;  
  FIG. 6 is a sectional view taken on the lines 6-6 of FIG. 2;  
 FIG. 7 is a sectional view of a header module;  
  FIG. 8 is a sectional view of a portion of a multiposition diverter;  
  FIGS. 9 and 10 are sectional views showing the hydraulic actuator mechanism for the multi-position diverter of FIG. 8;  
  FIG. 11 is a detailed sectional view of the stab connector assembly for the multi-position diverter;  
  FIG. 12 is a schematic diagram of the hydraulic control system for the muIti-position diverter; and  
  FIG. 13 is a detailed sectional view showing a hydraulic line stab connector and valve.  
 DETAILED DESCRIPTION Referring to FIG. 1, there is shown a multiple well installation on the ocean floor. The numeral 10 indicates generally a template frame which is lowered onto the ocean floor and serves as both a template for drilling a plurality of wells and as a base for equipment used in the completion and operation of the wells after they are drilled. The frame is of open tubular construction consisting of two parallel grids, an upper grid indicated generally at 12 and a lower grid indicated generally at 14, preferably welded from sections of pipe. The two grids are supported in spaced parallel relationship by vertical pipes to form a plurality of cubical sections. The pipes are welded or otherwise joined to form a rigid integral structure.  
  In the center of each of the square openings of the upper grid 12 is mounted an annulus of flat ring 22 supported by diagonal frame members 24 which extend outwardly to the four corners of each section of the upper grid structure 12. Guide rods 25 project upwardly at each of the pipe intersections of the upper grid 12.  
  In a typical installation, a number of cubical sections offrame 10 would be used as the template for slant drilling one well from each section. Each well is drilled by conventional floating drilling equipment which utilizes the guide rods 25 and ring 22 to position the drilling equipment and locate the top of the well. As the well is drilled, surface casing is set through the central opening of the associated ring 22 and cemented in place, the top of the casing projecting up into the opening in the ring 22 to form the wellhead, as indicated at 50 in FIG. 2. Blowout preventors (not shown) are attached to the top of the casing and the well is drilled down to the producing formation.  
  After the drilling is completed, the tubing is run and hung in the wellhead, plugs are set in the tubing string prior to removing the blow-out preventors and drilling equipment. All of the completion equipment, including the production tree, valving, and related equipment needed to control flow of the well is mounted in a module which is lowered into position and attached to the wellhead in a manner hereinafter described. Three of these wellhead equipment modules are shown in FIG. 1, as indicated at 26, 27, and 28.  
  In addition to each of the wellhead sections with their completion equipment modules, the template frame 10, in a typical installation, includes sections for mounting additional modules, such as one or more header modules 29. One header module serves as a conduit system with suitable valving for controlling the flow of oil and/or gas under pressure from a group of wells. The header modules 29 in turn connect into a single gathering header 30 having a connector assembly 31 off to one side for connecting into a terminal assembly 32 for a group of pipes going to a gathering point (not shown). In addition, the typical installation may include one or more power equipment modules 33 which serve as a source of electrical and hydraulic power for operating all the other modules. In addition, separator modules may also be incorporated.  
  While the internal design and construction of the various types of modules differs depending upon their function, the external features are quite similar. Thus each module includes an outer enclosure 40 having a top 42 in the form of a truncated cone which terminates in an upper stab plate 44 at its upper end with a central axially aligned mandrel 46. The bottom 48 of each module enclosure 40 includes a connector stab ring 49 (see FIG. 2) which mates with the ring 22 at a module location in the template frame. A central hydraulically operated connector 56 in the bottom of each module locks onto a central mandrel 54 that is fixed relative to the template frame 10. The mandrel 54, in the case of the wellhead section, is part of a casing head 52 attached to the top of the well casing. The mandrel may be directly attached to the frame 10 or the ring 22 for those sections not used for drilling.  
  The template 10 includes production tubing which may include four lines going to each well. Typically there is one flow line and one service line for each well completion. The additional two lines may be provided for dual completion or provide for water and/or gas injection. In order to permit pigging tools which can be pumped down the lines, a minimum radius of five feet is provided for all in the tubing. The four flow lines terminate in stab connector receptable units, indicated at 62, which are mounted in the ring 22. Immediately below each stab connector unit 62 is a nipple 64 for seating a conventional wireline-operated plug (not shown). Also mounted in the ring 22 are a plurality of hydraulic pressure line connectors 66. Hydraulic lines (not shown) extend from these connectors below the ring 22 to corresponding connectors in the ring 22 associated with the mounting of the power equipment module 33. These hydraulic lines are used to control all valving operations within the wellhead completion module 26 from the power equipment module 33. The hydraulic lines, apart from the connectors, have not been shown in the drawings for the sake of clarity. The use of hydraulic controls for valves and the like is well known in the art.  
  The wellhead completion module 26, when in position, connects onto the mandrel 54 through a connec tor 56 on the bottom of a production tree 58. The stab ring 49 has flow line mandrels 68 which engage the connectors 62 in the ring 22 to provide a fluid-tight coupling with the flow lines into the wellhead completion module. In addition, the stab ring 49 includes a plurality of hydraulic line connectors (not shown) which engage the hydraulic line connectors 66 in the stab ring 22 to provide hydraulic connections into the module 26 from the template.  
  The flow lines within the module 26 extend in large radius loops into the production tree 58. The flow line and service line are connected into the production tree through diverters 70, 72, 74, and 76. The diverters 70 and 72 permit direct access from the top of the module 26 into the tubing within the well bore. Thus the diverter 70 connects to a vertical tubing section 78 which extends into a central fitting 80 at the top of the production tree 58 which terminates in the mandrel 46 projecting above the stab plate 44. A conventional riser with a stab connector can be attached to the mandrel 46 from the surface to permit access into the well tubing from the surface for rework tools, or the like. The tubing section 78 may be controlled by a hydraulically operated valve 82 and may also include a nipple for receiving a conventional plug to back up the valve 82 and insure that no fluid under pressure can escape from the well out through the tubing 78.  
  Similarly, the diverters 74 and 76 are connected by vertical tubing sections 86 and 88 to stab connector fittings 90 and 92, respectively, mounted in the upper stab plate 44. Again, each of these tubes is provided with hydraulically controlled valves 94 and 96. In addition, nipples 98 and 99 are provided just below the stab connector fittings 90 and 92 for receiving removable plugs.  
  Initially plugs are set in the nipples 64 at the terminus of the flow lines within the template frame before the frame is lowered and secured in place on the ocean floor. After the well is drilled and it is desired to mount the well completion module in place, a multiple diverter assembly 100 is connected to the top of the mod ule before the module is lowered into place. The multiple diverter assembly includes a connector stab ring 102 having stab connector elements 101 which mate with the connectors 90, 92 and a sealed off connector 103 that engages and locks onto the central mandrel 46. There are also hydraulic line connectors 105 in the stab plate 44 which engage corresponding hydraulic line connectors 107 in the stab ring 102. Hydraulic lines (not shown) extend from the surface and are connected into the module to provide control of the module. The hydraulic line connectors 107 when inserted in the connectors 105 are arranged to block the control lines going to the connectors in the base of the module so as to prevent normal control from the power module while the multiple diverter assembly 100 is connected to the module.  
  As shown in detail in FIG. 13, the stab connector 105 has an interior chamber 109 having an inlet passage 111 and an outlet passage 112. A second inlet passage 113 receives the nipple of the stab connector when the multiple diverter unit 100 is attached to the module. Inside the chamber 109 is a valve plunger 115, the upper end of which normally seats against a valve seat 117 at the stab connector inlet 115. A spring 119 urges the valve against the seat 117. The inlet 111, which is connected by a hydraulic line (not shown) to a stab connector in the base of the module, is normally fluidcoupled to the outlet 112 to provide a control of some hydraulic device within the module through the template. However, when the multiple diverter 100 is in position, the stab connector entering the inlet 113 forces the plunger 115 downwardly against the spring into position to seal off the inlet 111. Thus hydraulic control is switched from the inlet 111 to the inlet 113. This insures that control within the module is trans ferred from the template to the surface through the multiple diverter 100 while it is attached to the top of the module.  
  The upper end of the multiple diverter assembly 100 includes a conical frame 106 and a base 104 joined by the frame 106 to a mandrel 108 by which the assembly can be attached to a riser (not shown). The base 104 in turn has a plurality of tube sections 110 which are coupled by the associated connectors to the tube sections 86, 88 within the wellhead completion module 26.  
  The multiple diverter assembly 100, described below in detail, includes a rotary assembly including a tubing section 114 which terminates in its upper end in a rotary coupling 116 that couples the tubing section 114 to the mandrel 108. The lower end of the tubing section 114 is joined to a retractable connector assembly indicated generally at 118 mounted on a rotary plate 120. The plate 120 is rotated by a hydraulic motor 122. The multiple diverter assembly is described in more detail below in connection with FIG. 8.  
  The wellhead completion module 26, with the multiple diverter assembly 100 connected to it, is lowered from the surface by a riser connected to the mandrel 108. The multiple diverter assembly is provided with suitable guide means including four parallel annular guide members 124 which are supported on the ends of radially extending arms 126 joined at their inner ends to the periphery of the stab ring 102. The guide members 124 engage the vertical guide posts or rods 25 projecting upwardly at the four corners of each section of the upper grid 12 of the template frame 10. By this arrangement, once the module 26 is guided into position and stabbed into the connector ring 22 and placed in operative condition, the multiple diverter assembly can be detached from the mandrel 46 and pulled to the surface. Since the module itself does not have any guide members which engage the vertical guide posts 25 of the frame 10, the guide posts can be shared by adjoining sections. Thus each module does not require its own set of guide posts in the template frame.  
  Once the wellhead completion module 26 is lowered into position, the plugs in the flow lines in the template are removed. This is accomplished by angularly positioning and engaging the rotary assembly so as to provide a connection to each one of the tubes in succession and running a wire line tool from the surface through the riser, through the top of the module 26 and each corresponding one of the tubes 86, 88 through the associated one of the diverters 74 and 76 to release and remove each of the plugs in the template flow lines. Each plug is withdrawn vertically through the module 26 and the multiple diverter 100.  
  After the plugs are removed from each of the flow lines in this manner, plugs may then be set in the nipples 98 and 99 adjacent the top of the module and the multiple diverter assembly 100 can then be detached from the top of the module 26 and the well placed in production.  
  If after the well is in production, any rework is required. a conventional riser can be attached to the mandrel 46 to permit rework tools to be lowered through the production tree 58 into the well. If for any reason it is necessary to replace or repair the production tree or any of the related valves or controls within the module 26, the multiple diverter assembly 100 can be lowered into position and stabbed into the top of the module 26. The plugs are then removed from the nipples 98 and 99 and plugs are set in the nipples 64 within the template frame 10 below the connector ring 22, and the tubing within the well is plugged below the mandrel 54. The entire module 26 can then be detached at the connectors mounted in the rings 22 and the wellhead connector 56, and the module 26 then can be pulled to the surface.  
  One of the significant features of this arrangement is that the well and all associated flow lines and service lines can be sealed off by removable plugs and there is no reliance on remotely-controlled valves for this purpose. No valves are required within the template assembly which is permanently mounted on the floor of the ocean. All valves are mounted within the removable modules. All terminations of flow lines within the template frame 10 are accessible by wire line tools from the surface without disconnecting or removing any of the modules. One module can be removed from the system without affecting the rest of the system in any way. All flow lines extending to the various wells remain under pressure even if one or more of the modules is removed from the system. There is no dependence on remotely controlled valves which could be inadvertently operated, permitting any of the flow lines to be accidentally opened to the sea with the attendant escape of oil or gas into the environment.  
  Another feature of the present invention is that each module is fully enclosed, except that sea water may be permitted to enter from the bottom to fill the space within the module. A plurality of vertically spaced sensors 130 are mounted in the wall of the module enclosure for sensing the presence of saltwater within the module. If there is any leakage of oil or gas within the module, it will displace the saltwater at the top, forcing the level of the saltwater downwardly. The sensing elements 130 provide a means of remotely monitoring any leakage, permitting remedial action to be taken whenever any leak in the system develops. The sensors may be a pair of spaced electrical terminals which are effectively shorted out by the saltwater which is a good conductor of electricity. When the saltwater is displaced by oil or gas, the resistivity of the gap increases abruptly. This change in resistivity can be sensed by conventional resistance measuring means.  
  Referring to FIG. 7, there is shown a typical header module for a group of five wells. As in the case of the wellhead completion module, the header module includes a cylindrical outer shell 121 having a truncated conical top 123 and a flat bottom 124. A stab ring 126 in the bottom of the module engages a mating stab ring 22 in the template frame 10. For a header servicing five wells, for example, a total of 12 flow lines are connected to the header module through the stab ring 127. The header is designed to provide a pair of lines for each well, a flow line and a service line.  
  The sectional view of FIG. 7 shows the five flow lines from five different wells coming into the stab ring 22, as indicated at 131, 132, 134, 136, and 138. An output flow line 140 goes to a separator module. Each of the flow lines is provided with a nipple for setting a plug, such as indicated at 142, positioned where the flow line connects to the stab ring 22.  
  Within the header module, each of the line connections from the stab ring 126 is connected through a valve, such as indicated at 144, into a standard diverter 146. One branch of the diverter 146 is connected by a section of tubing 148 through a plug nipple 150 to a connector element in an upper stab connector ring 152. Each of the tubing sections 148 may include a hydraulically operated valve, such as indicated at 154. A mandrel 156 is provided for attaching the multiple diverter to the top of the module. However, the mandrel, as shown, does not provide for connection to any internal part of the header module, but may be used for this purpose.  
  The diverters on each of five incoming flow lines from the respective wells are connected by tubing loops, such as indicated at 158, to the outgoing flow line through a group of series-connected diverters 160. These loops permit a pigging tool to be forced through the header from the line 140 and diverted to any one of the five wells serviced by the header. The header module can be provided with sensors, such as indicated at 162, for sensing the level of saltwater within the module. Both the upper and lower stab rings provide connections for all electricl and hydraulic lines to operate the valves and to operate the connector to release the connection between the module and the template frame.  
  The power modules and separator modules are similarly arranged with suitable stab connectors at both the bottom and the top of the module enclosures, permitting a multiple diverter 100 to be attached to the top of the module and permitting wire line tools to set plugs through the module into the flow lines below the module. The design of such hydraulic power equipment and oil, gas, and water separators is well known and forms no part of the present invention. Therefore detailed description of these modules is not believed necessary to teach the invention.  
  All the components required to implement the invention as thus far described are conventional components presently available on the market, with the exception of the multiple diverter. The standard hydraulically operated diverters, stab rings, valves, plugs, etc., are of conventional design.  
  A suitable design for a hydraulically operated multiline diverter is shown in FIGS. 8, 9, and 10. As shown in FIG. 8, the mandrel 108 at its lower end is provided with a flange 164 which is bolted or otherwise secured to a collar 166 at the upper end of the conical frame 106. The mandrel 108 has a counterbore 168 which receives the upper end of the tubing section 114, the tubing being rotatable within the bore 168 and being provided with suitable rotary seals to withstand full tubing pressure.  
  The tubing 114 is curved so that the lower end of the tubing is offset from the central axis of rotation of the upper end of the tubing 114. As pointed out above, the tubing 114 provides a rotating assembly which includes a rotating plate that slidably engages the mating base plate 104. The rotating assembly includes a frame plate 170 which is secured at its lower end to the rotary plate 120 and which is welded or otherwise secured to the length of tubing 114 to provide rigidity to the assembly. Rotation of the plate 120 about the central axis of revolution moves the connector assembly 118 through 360. The hydraulic actuator 122, hereinafter described in detail, applies rotary motion to the plate 120 so as to position the connector 118 in alignment with any one of a plurality of tubing sections 110 attached to the plate 104 at angularly spaced positions.  
  Details of a suitable hydraulic actuator for the multiple diverter is shown in FIGS. 9 and 10. The actuator includes a shaft 172 terminating in an upper cap 174 which may, for example, be hexagonal in shape or have some other non-circular shape by which it is keyed in a corresponding opening in the rotating plate 120. The shaft 172 extends through a central opening 176 in the fixed base 104. Journaled on the outside of the shaft 172 is a rotatable collar 178 which extends between the bottom of the base 104 and a retaining washer 180 secured to the lower end of the shaft 172 by a nut 182. An overrunning clutch assembly, indicated generally at 184, concentrically positioned between the inside of the collar 178 and the shaft 172, permits torque to be transmitted in only one direction of rotation of the collar 178 to the shaft 172. Angular rotation is imparted to the collar 178 through a pair of downwardly projecting pins 186 which engage a hydraulic actuator assembly, indicated generally at 188 supported below the end of the shaft 172 from the frame base 104 by a housing 190.  
  The hydraulic actuator assembly 188 includes a pair of double-ended piston assemblies 192 and 194. Each of these double-ended piston assemblies includes a central yoke element 196 which slidably engages one of the associated pins 186, whereby reciprocal motion of the double-ended piston assemblies moves the pins 186 in a direction to impart rotation to the associated collar 9 178. Each end of each double-ended piston assembly terminates in a piston, as indicated at 198 and 200, that extends into a telescoping cylinder including a cylinder head 202 and telescoping cylinder element 204. By this arrangement, fluid under pressure admitted to either end of the double-ended piston moves the piston laterally and moves the pin 186 through sufficient distance to impart a 90 degree increment of rotation to the collar 178. As indicated by the dotted line 206, a stop element may be provided on the inside of the cylinder head for limiting the stroke of the double-ended piston to provide for limited angular rotation of the collar 178. For example, angular rotation might be limited to 45 where the multiple diverter is to be moved through eight angular diverter positions. The overrunning clutch 184 insures that with each reciprocal stroke of the double-ended pistons, the shaft 172 is advanced angularly in one direction through whatever angle of rotation is provided by the maximum length of stroke of the actuator pistons.  
  FIG. 11 shows the connector assembly 118 for providing a fluid-tight connection between the rotating tubing section 114 and any one of the plurality of tube sections 110 extending below the base 104. The connector assembly 118 includes a housing 210 which threadably engages a counterbore opening 212 in the moving plate 120. A nipple 214 slidably engages an internal bore 216 in the lower end of the housing 210. The upper end of the nipple 214 slidably engages a bore 218 in a coupling member 220, the upper end of which is joined to the tube section 114 and which is threaded into the member 210. A piston 222 integral with the nipple 214 slides within an enlarged cylindrical portion 224 within the coupling member 220. As shown in FIG. 11, the nipple 214, when in its lower or extended position, has the lower end 226 seated in a bore 227 in a connector element 228. The connector element 228 is threadably secured to the base 104 and provides a coupling to the tubing section 110 by means of a coupling assembly 229.  
  A hydraulic fitting 230 admits fluid under pressure into an annular chamber 232 through which fluid is admitted to the region below the piston 222 at 233. Thus fluid pressure admitted through the coupling 230 forces the piston 222 and associated nipple 214 upwardly, withdrawing the lower end 226 from its seating position in the connector element 228. When the nipple 214 is fully retracted, the movable plate 120 is free to be rotated relative to the base 104 by the hydraulic motor 122 to the next line connector position in the base 104.  
  A second hydraulic fitting 234 admits fluid under pressure into an annular chamber 236 into the region above the piston 222. Thus fluid under pressure through the fitting 234 pushes the piston 222 and associated nipple 214 downwardly into position to engage the connector element 228. The internal bore 227 of the connector element 228 is tapered, as indicated at 238, as is the outer lower surface of the nipple 214, as indicated at 240. This permits the nipple 214 to stab into the connector element 228 even though there is slight misalignment between the nipple 214 and the connector element 228.  
  FIG. 12 shows the hydraulic arrangement for operating the multiline diverter assembly 100. An advancing cycle is initiated by applying fluid under pressure to a hydraulic line 242 which goes to the fitting 230 on the connector assembly 118. This causes the nipple 214 to be retracted from the connector element 228. The line 242 is also connected through a pressure-operated valve 244 to one side of the double-ended pistons in the actuator assembly 188. When the pressure in the line 242 builds up to a predetermined level, it opens the valve 244, permitting one side of the double-ended pistons of the actuator 188 to move in a direction to advance the rotating plate and position the connector assembly 118 opposite the next connector position on the base 104. Hydraulic pressure is then switched to a hydraulic line 246 connected to the hydraulic fitting 234, admitting fluid under pressure to the back side of the piston 222 and advancing the nipple 214 to engage the associated connector element 228 at the new connector position. A pressure-operated valve 248 then admits fluid under pressure from the line 246 to the other end of the double-ended pistons of the actuator assembly 188 to reset the actuator and complete the indexing cycle. Thus it will be seen that each cycle causes the nipple to be retracted, the diverter to be advanced to the next connector position, the nipple to be set to provide a sealed connection, and the actuator to be reset.  
  From the above description it will be seen that the present invention provides an apparatus by which a group of subsea wells can be completed and serviced entirely from the surface of the sea by having all wellhead equipment mounted in modules which can be positioned or replaced on the top of each wellhead using surface equipment. One of the significant features of the invention is the ability to enter the wellhead or the flow lines connected to the module from the surface through the module itself without removal of the module. This arrangement permits plugs to be set or removed by wireline tools or by pump-down tools from the surface after the modules are in position. The multiposition diverter which can be secured to the top of a module by stab connections permits any one of the flow lines to be entered by a wireline or pump-down tool from the surface through a common riser.  
 What is claimed is:  
  1. A subsea well completion apparatus comprising: a template frame positioned on the sea floor, the template frame having a plurality of sections, each section including a plurality of stab connectors, flow tubing mounted in the template frame for inter-connecting the stab connectors of different sections, a plug-seating nipple in each flow line below each flow line stab connector for receiving and seating a removable line plug, a plurality of wellhead completion modules, each module having a top and a bottom, the bottom including a plurality of stab connectors adapted to engage the stab connectors of one of said template frame sections to complete flow line connections between the module and the template frame, the top including a plurality of stab connectors, flow lines in the module extending between stab connectors in the bottom and top of the module, a well completion valve tree in each completion module, the tree including casing connector means in the bottom for connecting the tree to the wellhead casing, and means including tool diverters connecting the flow lines in the module to the valve tree for providing a path for pump-down tools through the flow lines in the template into the well through the tree while providing a line tool path into the flow line in the template through said flow lines extending between the top and bottom stab connectors of the module.  
  2. Apparatus of claim 1 further including a nipple in each flow line adjacent the stab connectors in the top of each completion module for receiving and seating a removable line plug.  
  3. Apparatus of claim 1 wherein the centers of the flow line stab connectors in the top are equally spaced around a common circle.  
  4. Apparatus of claim 2 further including a multiposition diverter for selectively connecting each of the flow line stab connectors in the top of a module to a single riser, and means for removably securing the diverter to the top of the module.  
  5. Apparatus as defined in claim 1 wherein each completion module includes a housing, the stab connectors opening through the top and bottom walls of the housing, and means for sensing the level of oil accumulated and trapped within the housing.  
  6. Apparatus of claim 1 wherein the mating stab connectors in each section of the template frame and the bottom of the associated module are positioned in a ring extending around the associated wellhead.  
  7. Subsea well completion apparatus for providing completion of wells drilled in the sea floor comprising: a frame adapted to be positioned on the sea floor, the frame having an opening through which a well is drilled, a plurality of flow lines mounted on and secured to the frame, a plurality of stab connectors mounted on the frame and positioned in proximity to said opening, the flow lines terminating in the stab connectors, and plug-seating nipple means for receiving a line plug positioned in each of the flow lines, an enclosed wellhead completion module including a valve tree and flow lines connected to the valve tree, means connecting the valve tree to the top of the well, and a plurality of flow line stab connectors on the end of the flow lines in the completion module and positioned on the bottom of the module to engage the stab connectors in the frame when the valve tree is connected to the well.  
  8. Apparatus of claim 7 wherein the stab connectors extend vertically.  
  9. Apparatus of claim 8 wherein the completion module further includes a plurality I of tube connectors opening at the top of the module, and tube means including line tool diverters in the module connecting the upper connectors to the stab connectors in the bottom of the module.  
  10. Apparatus of claim 9 further including a multiposition wire line diverter, means removably securing the multi-position diverter to the top of the completion module, the diverter including means engaging all of the connectors in the top of the module, a riser connector, and rotating means selectively coupling the riser connector to each of the connectors in the top of the module.  
  11. Apparatus of claim 10 wherein each module further includes tool diverter means in the fluid flow lines between the top and bottom of the module.  
  12. Apparatus of claim 10 further comprising a diverter assembly for selectively coupling any of the fluid flow lines in a module to a common riser extending above the module, the diverter assembly including a plurality of stab connectors adapted to simultaneously engage the stab connectors in the top of a module, and  
 means for detachably securing the diverter assembly to the top of a module.  
  13. Apparatus of claim 12 wherein the diverter assembly includes rotary positioned coupling means for selectively coupling any one of the stab connectors to the riser.  
  14. Apparatus of claim 12 wherein the template frame further includes a plurality of vertically projecting guide posts secured to the frame around each connector element position, the diverter assembly including guide means engaging said posts for guiding the diverter assembly into position directly above any selected one of the well positions.  
  15. Apparatus of claim 12 further comprising a plurality of hydraulic control line connectors in the connector ring, matching hydraulic control line stab connectors in the bottom of the module, a plurality of hydraulic control line connectors in the top of the module, and a plurality of matching hydraulic control line stab connectors in the diverter assembly, and valve means in the module actuated by the diverter assembly when connected to the top of a module for cutting off all hydraulic control lines from the connectors in the bottom of the module, whereby hydraulic control of the module through the template is interrupted by connecting the diverter assembly to the top of the module.  
  16. Apparatus for subsea completion and operation of oil and gas wells comprising: a template frame adapted to be positioned on the sea floor, the template frame including a plurality of connector elements, each element including a plurality of stab connectors, and fluid flow lines interconnecting the stab connectors of different connector elements, each flow line including plug-seating nipples for receiving a line plug, and a plurality of modules for completing and operating wells drilled adjacent selected ones of said connector elements, each module including means detachably securing the module to a wellhead, a plurality of fluid line stab connectors mounted in the bottom of the module adapted to engage the stab connectors of the associated connector element in fluid-tight relationship when the module is secured to the associated wellhead, a plurality of flow line stab connectors opening at the top of the module, and flow lines extending directly between the stab connectors in the top to associated stab connectors in the bottom of the module, the flow lines being adapted to guide a wire line tool through the top of a module into the fluid flow lines in the template frame to set or remove plugs in said plug seating nipples below the connector elements.  
  17. Apparatus of claim 16 wherein each module further includes plug seating nipples in each of said fluid flow lines extending between the top and bottom of the module.  
  18. A multiline diverter assemblycomprising a group of flow line connectors arranged in a circle, a single flow line connector positioned along the axis of rotation of said circle, a fluid flow line section, rotating coupling means connecting one end of said section to said single connector, power-operated connector means positioned on the other end of said section and adapted to connect and disconnect said section from any one of said flow line connectors, and poweroperated indexing means for rotating said section to move the power-operated connector means into engaging position with any one of the group of flow line connectors.  
  19. Apparatus of claim 18 further including control means for successively disconnecting the poweroperated connector means from a flow line connector, rotating said flow line section to a position opposite the next flow line connector, and reconnecting the poweroperated connector means.  
  20. Apparatus for subsea completion and operation of oil and gas wells comprising: a template frame adapted to be positioned on the sea floor, a plurality of modules adapted to be removably mounted on top of the template frame, each module being positioned at one of said sections, the template frame including a plurality of fluid flow lines extending between the sections, each fluid flow line including a vertically extending stab connector at each end, each fluid flow line further including a plugseating nipple for receiving a line plug, each module including a plurality of vertically extending stab connectors at the bottom of the module positioned to engage the stab connectors terminating the fluid flow lines in the associated template section, a plurality of stab connectors opening at the top of each module, and flow lines extending between stab connectors at the bottom of a module and associated stab connectors at the top of a module for directing a wire line tool through the module to the plug-seating nipples in the associated flow lines in the template frame.  
  21. Apparatus of claim 20 wherein a portion of the modules includes a wellhead valve tree for connecting to a wellhead, and a portion of the modules includes header means for fluid connecting groups of fluid flow lines in the module to individual flow lines in the module.  
  22. Apparatus of claim 20 wherein each module further includes plug seating nipples in each of said fluid flow lines extending between the top and bottom of the module.  
  23. Apparatus of claim 20 wherein each module further includes tool diverter means in the fluid flow lines between the top and bottom of the module.  
  24. Apparatus of claim 20 further comprising a diverter assembly for selectively coupling any of the fluid flow lines in a module to a common riser extending above the module, the diverter assembly including a plurality of stab connectors adapted to simultaneously engage the stab connectors in the top of a module, and means for detachably securing the diverter assembly to the top of a module.  
  25. Apparatus of claim 24 wherein the diverter assembly includes rotary positioned coupling means for selectively coupling any one of the stab connectors to the riser.  
  26. Apparatus of claim 24 wherein the template frame further includes a plurality of vertically projecting guide posts secured to the frame around each connector element position, the diverter assembly including guide means engaging said posts for guiding the dilected one of the well positions.