Search Images Maps Play YouTube News Gmail Drive More »
Sign in
Screen reader users: click this link for accessible mode. Accessible mode has the same essential features but works better with your reader.

Patents

  1. Advanced Patent Search
Publication numberUS3754380 A
Publication typeGrant
Publication dateAug 28, 1973
Filing dateApr 5, 1972
Priority dateApr 5, 1972
Also published asCA946734A, CA946734A1, DE2316256A1
Publication numberUS 3754380 A, US 3754380A, US-A-3754380, US3754380 A, US3754380A
InventorsMc Minn R, Milnes D, Tournoux P
Original AssigneeBlack Sivalls & Bryson Inc
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Submarine oil well production apparatus
US 3754380 A
Abstract
The present invention relates to a submergible apparatus for producing an oil or gas well beneath the surface of a body of water which comprises an oil and gas separator having a pair of elongated horizontal ballast tanks attached thereto and means for selectively filling the ballast tanks with water or air. A pair of movable buoyancy vessels are attached to the separator and means for selectively moving the buoyancy vessels to alternate positions with respect to the separator are provided so that the apparatus has maximum stability while being towed on the surface of the body of water or submerged therein. A closed instrument capsule is removably attached to the separator which includes a liquid level controller for maintaining the liquid level within the separator at a desired level and means are provided for adjusting the liquid level controller from the outside of the instrument capsule.
Images(5)
Previous page
Next page
Claims  available in
Description  (OCR text may contain errors)

United States Patent McMinn et al.

SUBMARINE 01L WELL PRODUCTION APPARATUS [75] lnventors: Robert E. McMlnn; Paul M.

Tournoux, both of Oklahoma City, Okla; Donald S. Mflnes, Chessington, England [73] Assignee: Black, Sivnlls & Bryson, Inc.,

Oklahoma City, Okla.

[22] Filed: Apr. 5, 1972 211 Appl. No.: 241,143

[52] US. Cl 55/164, 166/5 [51] Int. Cl. B0111 19/00 [58] Field of Search 55/36, 45, 160, 164,

[56] Reierences Cited UNITED STATES PATENTS 2,767,802 10/1956 Orrell 55/174 X Primary Examiner-Samih N. Zaharna Assistant Examiner-Richard W. Burks Attorney-Jerry .l. Dunlap, Cv Clark Dougherty et all [57] STRALT The present invention relates to a submergible apparatus for producing an oil or gas well beneath the surface of a body of water which comprises an oil and gas separator having a pair of elongated horizontal ballast tanks attached thereto and means for selectively filling the ballast tanks with water or air. A pair of movable buoyancy vessels are attached to the separator and means for selectively moving the buoyancy vessels to alternate positions with respect to the separator are provided so that the apparatus has maximum stability while being towed on the surface of the body of water or submerged therein. A closed instrument capsule is removably attached to the separator which includes a liquid level controller for maintaining the liquid level within the separator at a desired level and means are provided for adjusting the liquid level controller from the outside of the instrument capsule.

Patented Aug. 28, 1973 3,754,380

5 Sheets-Sheet l q. in F El /A k I'll Patented Aug. 28, 1973 5 Sheets-Sheet 2 Patented Aug. 28, 1973 5 Sheets-Sheet 5 WJ H W SUBMARINE OIL WELL PRODUCTION APPARATUS BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates generally to a submergible oil well production apparatus, and more particularly, but not by way of limitation, to a submergible oil and gas separator apparatus for producing a well beneath the surface of a body of water. I

2. Description of the Prior Art The production of offshore oil and gas wells presents severe economic problems in that elaborate offshore platforms are generally required. Such platforms are used to support separation, dehydration, storage and other equipment required for producing the wells and are very costly to manufacture, install and maintain.

It has been proposed to utilize underwater production equipment located at each individual offshore well to reduce the number of offshore platforms required. For example, the installation of an underwater oil and gas separator at each offshore well head location would bring about a substantial reduction in platform space required. However, the installation and successful operation of such submergible separator apparatus presents severe technical problems, e.g., the apparatus must be capable of being towed on the surface of the water to a desired location and then submerged and installed on the sea bed or ocean floor. Further, once submerged and placed on the bottom, the apparatus must be capable of stabilizing itself during operation and it must be capable of resurfacing for service or change to a new well location. In addition, the apparatus must be capable of prolonged operation without the need for outside power, and major control functions must be adjustable from outside the apparatus during the operation.

By the present invention a submergible oil well production apparatus is provided having the above mentioned capabilities.

SUMMARY OF THE INVENTION The present invention relates to a submergible apparatus for producing a well beneath the surface of a body of water which comprises an oil and gas separator having a well stream inlet, gas outlet, oil outlet and a liquid level controller connection disposed therein. A pair of elongated horizontal ballast tanks are attached to the separator and means are provided for selectively filling the tanks with water or air thereby providing ballast or buoyancy to the apparatus. A pair of movable buoyancy vessels are attached to opposite sides of the separator and positioned so that the center of buoyancy of the apparatus is above the center of gravity thereof. Means for selectively moving the buoyancy vessels to alternate positions are provided attached to the buoyancy vessels so that the distance between the centers of buoyancy and gravity of the apparatus may be changed to provide maximum stability to the apparatus while being towed on the surface of the body of water or submerged therein. A removable instrument capsule is attached to the separator, the capsule including a liquid level controller connection and oil inlet and outlet connections. Liquid level control means are disposed within the instrument capsule for generating a control signal proportional to the variance between the actual liquid level within the separator and the desired liquid level, the liquid level control means being connected to the liquid level controller connection of the capsule. A conduit is provided removably connecting the liquid level controller connections of the separator and the instrument capsule, and a conduit is removably connected between the oil outlet of the separator and the oil inlet of the instrument capsule. Valve means responsive to the control signal generated by the liquid level control means are provided for controlling the flow rate of oil removed from the separator and the liquid level maintained therein, the valve means being disposed within the instrument capsule and connected between the oil inlet and outlet connections thereof. Means for adjusting the liquid level control means with respect to the desired liquid level to be maintained in the separator from outside the instrument capsule are provided attached to the instrument capsule.

It is, therefore, a general object of the present invention to provide a submarine oil well production apparatus.

A further object of the present invention is the provision of a submergible apparatus for producing an oil well beneath the surface of a body of water which may be towed on the surface to the well location and then submerged without requiring the utilization of a barge mounted crane or other ancillary equipment.

Yet a further object of the present invention is the provision of a submergible oil and gas separator which may be installed and operated on the sea bed or ocean floor and then economically recovered for service or relocation.

Another object of the present invention is the provision of an oil and gas separator apparatus which may be towed on the surface of a body of water, submerged therein and operated on the bottom with maximum stability.

Still another object of the present invention is the provision of a submarine oil and gas separator apparatus which may be operated on the sea bed or ocean floor for long periods of time without the need for outside power and wherein the major control functions of the separator may be adjusted from outside the apparatus by divers during the operation thereof.

Other and further objects, features and advantages of the present invention will be readily apparent to those skilled in the art from the following description of preferred embodiments when taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of the apparatus of the present invention,

FIG. 2 is a top plan view of the apparatus of FIG. 1,

FIG. 3 is a side elevational view of the apparatus of FIG, ll,

FIG. 4 is an elevational view of one end of the apparatus of FIG. 3,

FIG. is an elevational view of the other end of the apparatus of FIG. H,

FIG. 6 is a diagrammatic view illustrating the flow of the various streams through the separator and instrument capsule of the apparatus of FIG. 1 and the operation of the instruments within the instrument capsule,

FIG. 7 is a diagrammatic view of the hydraulic control system of the present invention for selectively moving the buoyancy vessels of the apparatus of FIG. I, and

FIG. 8 is a diagrammatic view of the ballast control system of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawings and particularly to FIGS. 1 through 5, the submergible oil well production apparatus of the present invention is illustrated and generally designated by the numeral 10. The apparatus 10 basically comprises a horizontal oil and gas separator 12 having a forward end 14 and a rearward end 16. A pair of elongated ballast tanks 18 and 211 are provided positioned parallel to each other and parallel to the axis of the separator 12. The ballast tank 18 is connected to the separator 12 by a plurality of support members 22, and the ballast tank 20 is connected to the separator 12 by a plurality of support members 24. As can be best seen in FIGS. 4 and S, the ballast tanks 18 1 and 20 are positioned in a horizontal plane a distance below the separator 12 and a plurality of horizontal support members 26 are connected between the tanks 18 and 20.

A pair of movable buoyancy vessels 28 and 30 are attached to the separator 12 by supporting arm assemblies 32 and 34 respectively. As best shown in FIGS. 2 and 3, the supporting arm assembly 32 is comprised of a central arm 36 rigidly connected at one end 38 thereof to the buoyancy vessel 28 and hinged at the other end 40 thereof to the separator 12 for movement in a plane perpendicular to the axis of the separator 12. A hydraulic jack assembly 42 for moving the arm 36 and buoyancy vessel 28 is pivotally attached to the central portion of the arm 36 and to the ballast tank 18. A

pair of outer arms 44 and 46 are provided on either side of the central arm 36. The outer arms 44 and 46 are rigidly attached to the buoyancy vessel 28 and hinged to the separator 12. A plurality of cross members 48 are provided connected between the central arm 36 and outer arms 44 and 46 to provide overall strength to the arm assembly 32.

The supporting arm assembly 34 is identical to the assembly 32 and includes a central arm 50 rigidly attached to the buoyancy vessel 30 at one end and hinged to the separator 12 at the other end. A hydraulic jack assembly 52 is provided attached to the central portion of the arm 50 and to the ballast tank 24, and a pair of outer arms 54 and 56 are provided attached to the buoyancy vessel 30 and hinged to the separator 12. Cross members 58 connect the central and outer support arms 50, 54 and 56 together to provide strength to the assembly 34.

As shown in FIGS. 1, 2, 4 and 5, a pair of tie bars 60 are removably connected to each of the buoyancy vessels 28 and 30 and to the ballast tanks 18 and 20 respectively. As will be described further hereinbelow, the tie bars 60 retain the buoyancy vessels 28 and 30 in the proper position for towing the apparatus 10 on the surface of a body of water.

The separator 12 includes an access passage or manway 62 positioned on the top thereof and a pair of hydraulic oil surge tanks 64 and 66, the operation of which will be described below, are mounted on top of the separator 12 at the rearward end 16 thereof. The separator 12 includes a drain connection 68 and a well stream inlet connection 70 positioned near the end 16 thereof. A gas outlet connection 72, an oil outlet connection 74 and a pair of liquid level controller connections 76 are provided in the separator 12 at the forward end 14 thereof.

An instrument capsule 80 containing the various instruments required for controlling the operation of the separator 12 is removably attached to the support member 26 in front of the end 14 of the separator 12. The instrument capsule 80 includes a pair of liquid level controller connections 82, a gas inlet connection 84, an oil inlet connection 86, a gas outlet connection 87, an oil outlet connection 88, a well stream inlet connection and a well stream outlet connection 92. In addition, a plurality of observation ports 94 are disposed in the sides of the instrument capsule 80 and three horizontal bars 96 are provided for handling the capsule during installation and removal thereof.

As can be best seen in FIGS. 2 through 5, the well stream inlet connection 90 of the instrument capsule 80 is connected to a conduit 98 by means of a conventional connector 100 and a shutoff valve 102 is provided in the conduit 98. In operation of the apparatus 10, the conduit 98 is connected to the manifold of a well to be produced. The well stream outlet connection 92 of the capsule 80 is connected to a conduit 104 by means of a connector 106 and the conduit 104 is connected to the well stream inlet connection 70 of the separator 12. A main shutoff valve 112 and a bleed valve are disposed in the conduit 104. A conduit 114 is provided connected to the conduits 98 and 104 between the shutofi' valves 102 and 112 so that the safety shutdown valve 168 may be bypassed. A bypass valve 116 is disposed in the conduit 114.

Oil separated within the separator 12 is removed therefrom by way of the oil outlet connection 74 thereof and a conduit 118 is connected to the oil inlet connection 86 of the instrument capsule 80 by way of a connector 126. A shutoff valve 120 and a bleed valve 124 are disposed in the conduit 1 18. The oil outlet connection 88 of the instrument capsule 80 is connected to a conduit 128 by means of a connector 130 and a shutoff valve 129 is disposed in the conduit 128.

Gas separated within the separator 12 is removed therefrom by way of the gas outlet connection 72 thereof and a conduit 132 which is connected to the gas inlet connection 84 of the instrumentcapsule 80 by a connector 140. A shutoff valve 134 and a bleed valve 138 are disposed in the conduit 132. A conduit 142 is connected to the gas outlet connection 87 of the instrument capsule 80 by a connector 144 and a shutoff valve 143 is disposed in the conduit 142.

A pair of conduits 146 connect the liquid level controller connections 76 of the separator 12 to the liquid level controller connections 82 of the instrument capsule 80 by way of a pair of connectors 154. The conduits 146 each have a shutoff valve 148 and a bleed valve 152 disposed therein.

A portion of the space between the ballast tanks 18 and 20 and the support members 26 positioned therebetween is enclosed to form a central float (FIG. 2), and as best shown in FIGS. 3 and 5, a regulator float 162 is attached to the central float at a position below the separator 12. The ballast tanks 18 and 20, the central float 160 and the regulator float 162 are connected to a ballast control system containing a variety of conduits and valves which is used for selectively filling or discharging the ballast tanks and floats with water ballast. This ballast control system is primarily contained within the central float 160 between the ballast tanks 18 and 20, and therefore, is not shown in FIGS. 1 through 5. However, it will be understood that a ballast control manifold is provided positioned on the apparatus in an easily accessible location. The ballast control system is schematically shown in FIG. 8 and will be described in detail hereinbelow.

A hydraulic control system for selectively moving the buoyancy vessels 28 and 30 is connected to the hydraulic fluid accumulator tanks 64 and 66 and the hydraulic jacks 42 and 52. This hydraulic control system is not shown in FIGS. 1 through 5, but is shown schematically in FIG. 7 and will be discussed in detail hereinbelow.

INSTRUMENT CAPSULE 80 Referring specifically to FIG. 6, the instrument capsule 80, the various instruments and controls contained therein and the hookup of the capsule 80 with the separator 12 are illustrated diagrammatically. A conventional float type pneumatic liquid level controller 160 is disposed within the instrument capsule 80 and connected to the liquid level controller connections 82 thereof. The oil inlet connection 86 of the capsule 80 is connected internally to the oil outlet connection 88 thereof by a conduit 162, and a conventional pneumatic liquid level control valve 164, responsive to the output control signal generated by the liquid level controller 160 is disposed within the conduit 162.

A conduit 166 internally connects the well stream inlet connection 90 of the instrument capsule 80 to the well stream outlet connection 92 thereof and a conventional normally closed pneumatic safety shut down control valve 168 is disposed in the conduit 166.

A conduit 170 internally connects the gas inlet connection 84 of the instrument capsule 80 with the gas outlet connection 87 thereof, and a conventional back pressure regulator 172 is disposed in the conduit 170. A conduit 174 is connected to the conduit 170 upstream of the back pressure regulator 172 and a gas dryer 176, preferably a small vessel filled with a dry desiccant such as activated alumina, is disposed in the conduit 174. A conventional pressure regulator 178 is disposed in the conduit 174 downstream of the gas dryer 176, and a conventional relief valve 180 is connected to the conduit 174 downstream of the regulator 178. A conduit 182 is connected to the conduit 174 and to the liquid level controller 160 for conducting supply gas to the level controller 160.

A pneumatic control valve 184 for injecting dry gas within the capsule 80 is attached to the conduit 174 and a threeway pneumatic control valve 186 for operating the well stream safety shut down valve 168 is connected to the conduit 174. A gas vent connection 188 is provided in the capsule 80 connected internally to a conduit 190 which includes a check valve 192 and a downstream pressure regulator 194 disposed therein.

OPERATION OF THE SEPARATOR 12 AND INSTRUMENT CAPSULE 80 Referring still to FIG. 6, the well stream from an oil or gas well being produced is flowed by way of the conduit 98, the shutoff valve 102 and the inlet connection 92 of the instrument capsule 80 into the conduit 166 contained therein. The well stream passes through the safety shut down valve 168 disposed in the conduit 166 and then exits the instrument capsule 80 by way of the well stream outlet connection 92 thereof. From the capsule 80 the well stream passes by way of the conduit 104 through the shutoff valve 112 and into the separator 12 by way of the inlet connection thereof.

The bypass conduit 114 and bypass valve 116 are utilized during initial start up of the apparatus 10. That is, in order to obtain a supply of instrument gas within the capsule and to the three-way control valve 186 so that the well stream safety shut down valve 168 can be opened, the system is initially pressured up by way of the bypass valve 116 and bypass conduit 114. Once pressure is established within the separator 12 and the safety shut down valve 168 opened, the bypass valve 116 is closed and theother shutoff valves are opened to place the separator 12 into operation.

As the well stream flows through the separator 12 it is separated into its oil and gas components in a conventional manner. The separated oil exits the separator 12 by way of the oil outlet connection 74 thereof and passes by way of the conduit 118 into the instrument capsule 80. That is, the oil flows through the conduit 118, the shutoff valve 120 and into the capsule 80 by way of the connection 86 thereof. The oil flows through the conduit 162 and control valve 164 within the instrument capsule 80 and exits the capsule 80 by way of the oil outlet connection 88 thereof. From the oil outlet connection 88 the oil is flowed by way of the conduit 128 and shutoff valve 129 to storage or further processing facilities generally located on an offshore platform.

The level of separated oil existing within the separator 12 is duplicated in the liquid level controller by means of the conduits 146 connected to the separator 12, and the controller 160 generates a pneumatic control signal which is proportional to variations between the actual level and a preselected desired level. This pneumatic control signal is communicated to the control valve 164 by way of the conduit 196. As is readily understood by those skilled in the art, the level controller 160 automatically opens and closes the valve 164 so that the desired oil level is maintained within the separator 12. An adjusting linkage assembly 202 is connected to the liquid level controller 160 from outside the capsule 80 so that the desired liquid level may be set and/or adjusted from outside the capsule 80 during the start up and operation of the apparatus 10.

The gas separated from the well stream within the separator 12 is removed therefrom by way of the gas outlet connection 72 thereof. The separated gas flows by way of the conduit 132, the shutoff valve 134 and the connection 84 of the instrument capsule 80 into the conduit 170. The gas passes by way of the conduit through the back pressure regulator 172 and then exits the capsule 80 by way of the gas outlet connection 87 thereof. From the gas outlet connection 87 of the capsule 80, the gas passes through the conduit 142 and shutoff valve 143 to further processing facilities generally located on an offshore platform. The back pressure regulator 172 functions to maintain the pressure of the separator 12 at a desired level in a conventional and well understood manner, and an adjusting linkage assembly 173 is connected to the regulator 172 from outside the capsule 80 so that adjustments in back pressure can be made during the start up and operation of the apparatus 10.

A portion of the gas passing through the conduit 170 is diverted by way of the conduit 174 through the gas dryer 176 wherein water contained in the gas is removed. The dried gas then passes through the pressure regulator 178 wherein the pressure of the gas is preduced to a level such that the gas may be utilized as instrument supply gas. The relief valve 180 functions to protect the system downstream of the pressure regulator 178 against over pressure and the conduit 182 leads a portion of the gas passing through the conduit 174 to the level controller 160 as supply gas. The remaining gas passes by way of the conduit 174 to the control valves 184 and 186.

The control valve 186 is a conventional pneumatically operated three-way valve of the type which may be caused to operate at a selected control signal pressure level. The pneumatic control signal generated by the liquid level controller 160 is conducted to the valve 186 by way of a conduit 198 connected to the conduit 196. A conduit 200 connects one of the outlet ports of the three-way valve 186 to the pneumatic operator of the normally closed well stream safety shut down valve 168. In operation of the control valve 184 it is set so that when the liquid level within the separator 12 reaches an abnormally high position and as a result the liquid level controller 160 generates a control signal at a high pressure level, the valve 186 vents the conduit 200 and the operator of the valve 168 thereby causing the valve 168 to close and the apparatus to shut down. An adjustment linkage assembly 204 is connected to the control valve 186 from outside the capsule 80 so that the valve 186 may be reset and adjusted from outside the capsule 80.

In order to insure a water free atmosphere is maintained within the instrument capsule 80, dehydrated gas is injected into the capsule by way of the control valve 184. The control valve 184 is a conventional pressure regulator which is responsive to a control signal, and functions to maintain the gas pressure level within the instrument capsule 80 at a desired increment above the pressure level of the body of water outside the instrument capsule 80. The water pressure exerted on the outside of the capsule 80 is communicated by way of the vent 188, the conduit 190 and the conduit 206 to the control valve 184. The control valve 184 is set to maintain the pressure level within the capsule 80 at a desired level above the water pressure, i.e., as the water pressure increases the valve 184 opens to raise the gas pressure level within the capsule 80 a corresponding amount and as the water pressure decreases the control valve 184 closes. The relief valve 194 senses the pressure level between it and the check valve 192 and functions to relieve pressure from the instrument capsule 80 by way of the check valve 192, the conduit 190 and vent 188. Thus, as the apparatus 10 is submerged in a body of water, the control valve 184 functions to automatically maintain the gas pressure within the capsule 80 at a level above the water pressure outside the capsule. As the apparatus 10 is raised to the surface, the relief valve 194 functions to lower the pressure level back to the original set pressure. That is, as the water pressure communicated by way of the conduit 190 to the check valve 192 decreases, gas pressure between the relief valve 194 and check valve 192 decreases causing the pressure regulator 194 to open.

When the instruments within the instrument capsule 80 require servicing, it is unnecessary to raise the entire apparatus 10 to the surface. Instead, the instrument capsule 80 may be removed from the apparatus 10. When removing the instrument capsule 80, the shutoff valves 102, 112, 134, 120, 148, 129 and 143 are closed and the bleed valves 110, 138, 152 and 124 are opened to insure the relief of pressure contained in the various conduits within and connected to the capsule 80. The connectors 100, 130, 144, 106, 140, 154 and 126 are next disconnected which allows the entire instrument capsule to be removed from the apparatus 10.

As will be understood, in adjusting the instruments contained within the instrument capsule 80 when starting up and operating the apparatus 10, the observation ports 94 disposed in the instrument capsule are utilized by a diver to observe the operation of the various instruments, the pressure levels, etc. The instrument adjusting assemblies 173, 202 and 204 are utilized by the diver to make appropriate changes in the separator liquid level, the separator back pressure and the safety shut down set point.

HYDRAULIC SYSTEM FOR SELECTIVELY MOVING THE BUOYANCY VESSELS 28 AND 30 Referring now to FIG. 7, the hydraulic system for moving the buoyancy vessels 28 and 30 is illustrated diagrammatically and is generally designated by the numeral 219. The hydraulic jacks 42 and 52 associated with the supporting arm assemblies 32 and 34 attached to the buoyancy vessels 28 and 30 are of conventional design. The jack 52 includes a cylinder 220 pivotally attached to the supporting arm assembly 34, and a piston assembly 222 is disposed within the cylinder 220 and pivotally attached to the ballast tank 20. The hydraulic jack 42 is identical to the jack 52 and includes a cylinder 224 pivotally attached to the supporting arm assembly 32 and a piston assembly 226 disposed within the cylinder 224 and pivotally attached to the ballast tank 18.

The upper hydraulic ports of the cylinders 220 and 224 are connected by conduits 228 and 230 respectively to a header 232. Shutoff valves 234 and 236 are disposed in the conduits 228 and 230 respectively, and the header 232 is connected by a conduit 238 to the hydraulic fluid accumulator tank 66. A shutoff valve 240 is disposed in the conduit 238. A body of hydraulic fluid 241 is contained in the tank 66 and the conduit 238 is connected to an internal siphon 67 extending to near the bottom of the tank 66. The lower hydraulic ports of the cylinders 220 and 224 are connected by conduits 240 and 242 respectively to a header 244. Shutoff valves 246 and 248 are disposed in the conduits 240 and,242 respectively, and the header 244 is connected by a conduit 250 having a shutoff valve 252 disposed therein to the hydraulic fluid accumulator tank 64. The tank 64 contains a body of hydraulic fluid 296 and the conduit 250 is connected to an internal siphon 65 which extends to near the bottom of the tank 64.

A source of high pressure compressed air, which is preferably comprised of two or more compressed air bottles 254 removably attached to the apparatus 10, is connected to a conduit 256. A high pressure regulator 258 is disposed in the conduit 256, and a conduit 260 is connected to the conduit 256 downstream of the regulator 258. A shutoff valve 262 is disposed in the conduit 260 and a hose connection 264 is attached to the valve 262. A shutoff valve 266 is disposed in the conduit 256 downstream of the point of connection of the conduit 260, and a low pressure regulator 268 is disposed in the conduit 256 downstream of the shutoff valve 266. A conduit 270 is connected to the conduit 256 downstream of the low pressure regulator 268 for conducting a supply of air to the ballast control system to be described in detail below. The end of the conduit 256 is connected to a header 272 which is in turn connected to a pair of conduits 274 and 278 having shutoff valves 276 and 280 disposed therein respectively. The conduit 274 is connected to the tank 66 and the conduit 278 is connected to the tank 6 4. The accumulator tanks 64 and 66 include conduits 222 and 284 respectively attached to the upper portions thereof and shutoff valves 2%6 and 299 are disposed in the conduits 282 and 284 respectively. Hose connections 288 and 292 are attached to the valves 236 and 2% respectively.

OPERATION OF THE HYDRAULIC SYSTEM 219 Referring still to FIG. 7, in operation of the hydraulic system 219 for moving the buoyancy vessels 28 and 30 to alternate desired positions, the high pressure regulator 258 is adjusted so that the downstream air pressure is approximately 750 psig and the low pressure regulator 268 is adjusted so that the air entering the conduit 270 and the header 272 is at a pressure level of approximately 104) psig. A high pressure air hose 294 is connected between the hose connection 264 and one of the hose connections 28% or 292 connected to the tanks 64 and 66 respectively, depending upon the desired direction of movement of the vessels 28 and 30. The use of the flexible hose 294 for providing air to one of the accumulator tanks 64 or 66 prevents the application of high pressure air to both tanks 64 and 66 simultaneously. Let it be assumed that it is desired to move the buoyancy vessels 2% and 30 towards the ballast tanks 18 and 20. The hose 294 is connected to the hose connector 288 attached to the accumulator tank 64, and the shutoff valve 286 is opened. The shutoff valve 262 is next opened to apply air pressure from the conduit 256 to the hydraulic fluid accumulator tank 64. As will be understood, when the air pressure is applied to the body of hydraulic fluid 296 contained in the tank 64, the fluid is forced into the conduit 250. The valve 290 attached to the tank 66 is opened to provide an atmospheric vent thereto, and with the valves 240 and 252 closed, the valves 248, 236, 234 and 246 are opened. The valve 240 disposed in the conduit 238 is next opened, and finally the valve 252 disposed in the conduit 250 is opened. As the valve 252 is opened, bydraulic fluid is forced through the conduit 250 into the header 244 through the conduits 24d and 242 and valves 246 and 243 into the lower portions of the hydraulic cylinders 220 and 224 respectively. The pressure of the hydraulic fluid entering the lower portions of the hydraulic cylinders 226 and 224 forces the hydraulic cylinders downwardly which in turn moves the supporting arm assemblies 32 34 and buoyancy vessels 28 and 30 downwardly. As the cylinders 226 and 224 move downwardly with respect to the pistons 222 and 226, hydraulic fluid is forced out of the upper portions of the cylinders 220 and 224 by way of the conduits 228 and 230 respectively. This hydraulic fluid passes through the valves 234 and 236 into the header 232 and into the accumulator tank 66 by way of the conduit 238 and valve 240.

Depending upon whether the apparatus is in or out of water, the force exerted on the buoyancy vessels 28 and 30 can be upward or downward. That is, when the apparatus 10 is out of the water gravity exerts a downward force on the vessels 28 and 30. When the apparatus 10 is in the water, the buoyancy of the vessels 28 and 30 exerts an upward force thereon. This makes a difference only in which of the valves 240 and 252 is opened first, i.e., if the apparatus 16 is out of the water the valve 240 is opened first and the valve 252 is used to control the movement of the vessels 28 and 30. If the apparatus 10 is in the water, the valve 252 is opened first and the valve 240 is used to control the movement.

If it is desired to move the buoyancy vessels 28 and 30 in the opposite direction, i.e., away from the ballast tanks 18 and 20, the valves mentioned above are closed and the hose 294 is removed from the hose connection 288 of the tank 64. The tanks 64 and 66 are vented by opening the valves 266 and 290, and the hose 294 is connected to the connector 292 of the tank 66 and the tank 66 is pressured up by opening the valve 262. With the valves 240 and 252 closed, the shutoff valves 248, 236, 234 and 246 are opened. The valve 252 is next opened (assuming the apparatus MP is not in the water) and the valve 240 is finally opened to allow hydraulic fluid under pressure to pass by way of the conduit 238, the header 232 and the conduits 228 and 230 into the upper portions of the cylinders 226 and 224. The bydraulic fluid entering the upper portions of the cylinders 220 and 224 causes the cylinders, the supporting arm assemblies 32 and 34 and the buoyancy vessels 28 and 30 to move upwardly. The hydraulic fluid forced out of the lower portions of the cylinders 220 and 224 passes by way of the conduits 246 and 242, the header 244 and the conduit 250 into the accumulator tank 64.

As will be described further herein, when submerging the apparatus 10, the buoyancy vessels 28 and 30 are allowed to move upwardly to their uppermost position and the hydraulic jacks 42 and 52 function to buffer the movement, i.e., the jacks act as dash pots. In order to set the hydraulic control system 21% up so that the jacks 42 and 52 act as dash pots, the various hydraulic fluid shutoff valves and vent valves mentioned above are closed and the hose 294 is removed from the system. The valves 276 and 226 are opened to allow air at a low pressure level to enter both the tanks 64 and 66 by way of the conduits 274 and 278 respectively. The valves 234, 236, 246 and 248 are next opened, and f1 nally the valves 252 and 240 are opened. As will be apparent to those skilled in the art, the jacks 42 and 52 will now act as dash pots, e.g., as the vessels 28 and 30 are moved upwardly by the submergence of the apparatus l0, hydraulic fluid is forced by way of the conduits 240 and 242, the header 244 and the conduit 250 into the tank 64. Because of the displacement of the hydraulic fluid into the tank 64 and the corresponding movement of fluid out of the tank 66, the upward movement of the vessels 26 and 36 is buffered and the speed at which the vessels 2% and 30 move can be controlled by manipulating the valve 252.

BALLAST CONTROL SYSTEM Referring now to FIG. 8, the ballast control system of the apparatus 10 is illustrated diagrammatically and is generally designated by the numeral 299. Each of the ballast tanks 18 and 20 are divided into a plurality of compartments. Specifically, the ballast tank 18 includes a closed compartment 3% at one end, a closed compartment 362 at the other end, and compartments 304, 306, 30%, 310 and 3H2 positioned therebetween. The compartments 394, 306, 308, 316 and 312 are closed at the bottom to insure equal distribution of the ballast water, but are communicated at the top portions thereof. The ballast tank 20 includes a closed compartment 314 at one end, a closed compartment 316 at the other end and partially closed compartments 318, 320, 322, 324 and 326 therebetween. A water intake header 328 is attached to the apparatus which includes a water inlet connection therein. Preferably, one of the horizontal support members 26 of the apparatus 10 previously described is used for this purpose. Each of the compartments of the ballast tanks 18 and 20 are connected to the water intake header 328 by a separate conduit. That is, the compartments 300, 304, 306, 308, 310, 312 and 302 of the ballast tank 18 are connected to the header 328 by conduits 300, 332, 334, 336, 340 and 342 respectively having valves 344, 346, 348, 350, 352, 354 and 356 disposed therein respectively.

The compartments 314, 318, 320, 322, 324, 326 and 316 of the ballast tank 20 are connectec to the water intake header 328 by conduits 358, 360, 362, 364, 366, 368 and 370 respectively having valves 372,. 374, 376, 378, 380, 382 and 384 disposed therein respectively.

Each of the closed compartments 300, 302, 314 and 316 of the ballast tanks 18 and 20 are vented to a header 286. That is, the compartment 300 is connected to the header 386 by a conduit 388 having a shutoff valve 390 disposed therein, the compartment 302 is connected to the header 386 by a conduit 392 having a shutoff valve 394 disposed therein, the compartment 314 of the ballast tank 20 is connected to the header 386 by a conduit 396 having a valve 398 disposed therein and the compartment 316 is connected to the header 386 by a conduit 400 having a shutoff valve 402 disposed therein. The header 386 is connected by a conduit 404 to a conduit 406 which is in turn connected to an atmospheric vent 408. A shutoff valve 410 is disposed in the conduit 404.

The central float 160 of the apparatus 10 is connected to the water intake header 328 by a conduit 412 having a shutoff valve 414 disposed therein. A vent conduit 416 is connected to the central float 160 and to the conduit 406. A shutoff valve 418 is disposed in the conduit 416.

The regulator float 162 of the apparatus 10 is connected to the water intake header 328 by a conduit 420 having a shutoff valve 422 disposed therein. The regu-. lator float is vented by a conduit 424 which is connected to the common port of a manually operated three-way valve 426.

The conduit 270, connected to the low pressure air supply described above in connection with the hydraulic control system 219, is connected to a port of the three-way valve 426, and the remaining port is connected by a conduit 428 having a shutoff valve 429 disposed therein to the conduit 404. A conduit 430 is connected to the conduit 270 and to the conduit 404. A shutoff valve 432 is disposed in the conduit 430.

The compartments 304, 306, 308, 310 and 312 of the ballast tank 18 are vented by a conduit 434 and the compartments 318, 320, 322, 324 and 326 of the ballast tank 20 are vented by a conduit 438. Both the conduits 434 and 438 are connected to a conduit 436 having a shutoff valve 440 disposed therein. The conduit 436 is connected to the conduit 406.

OPERATION OF THE BALLAST CONTROL SYSTEM 299 In operation of the ballast control system 299 to bring about the submergence of the apparatus 10, the

central float is flooded by opening the vent valve 418 and the water intake valve 4l4. When the central float 160 is completely flooded the valve 414 is closed.

The shutoff valve 440 in the conduit 436 is next opened to vent the compartments 304, 306, 308, 310 and 312 of the ballast tank 18 and the compartments 318, 320, 322, 324 and 326 of the ballast tank 20. The compartments 304, 306, 308, 310 and 312 of the ballast tank 18 and the compartments 318, 320, 322, 324 and 326 of the ballast tank 20 are simultaneously flooded by opening the water intake valves 346, 348, 350, 352, 354, 374, 376, 380 and 382. Once the intermediate compartments of the ballast tanks 18 and 20 are completely flooded the vent valve 440 is closed and the various water intake valves corresponding thereto are closed.

The closed compartments 300, 302, 314 and 316 of the ballast tanks 18 and 20 are utilized to trim the apparatus 10 prior to submergence. That is, the compartments 300, 302, 314 and 316 are partially filled with water to bring the apparatus 10 into a horizontal position. Preferably, diagonally opposed compartments 300 and 316 are filled simultaneously and then the compartments 302 and 314-are filled. This is accomplished by opening the valve 410 in the conduit 404 and the valves 390, 394, 398 and 402 so that the compartments 300, 302, 314 and 316 are vented. The water intake valves 344' and 384 are next opened to allow water to pass by way of the conduits 330 and 370 into the compartments 300 and 316. Once the compartments 300 and 316 have been filled to the desired level, the compartments 302 and 314 are filled by opening the water intake valves 356 and 358, respectively. As will be understood, the particular quantity of water added to each of the compartments 300, 302, 314 and 316 is controlled so that the proper amount of water ballast is taken on by the apparatus 10. Further, as mentioned above, the amount of water in each of the compartments 300, 302, 314 and 316 is adjusted so that the apparatus 10 is trimmed. Once the addition of water ballast to the compartments 300, 302, 314 and 316 has been completed, the vent valves 390, 394, 398 and 402 are closed and the water intake valves 344, 356, 372 and 384 are closed.

In the event it is desired to remove some of the water added to any or all of the compartments 300, 302, 314 and 316, this can be accomplished by opening the valve 432 with the valves 410 and 329 closed so that the air pressure from the conduit 270 is communicated to the header 386 by way of the conduits 404 and 430. One or all of the vent valves 390, 394, 398 and 402 are next opened to communicate air pressure to the compartments 300, 302, 314 and 316 and the appropriate water intake valves 344, 356, 372 and/or 384 are opened to allow water to flow from the compartments into the water intake header 328.

When the addition of water ballast to the ballast tanks 18 and 20 and the central float 160 has been completed, the three-way valve 426 is positioned so that the conduit 424 is communicated with the conduit 428 and the valves 424 and 410 are opened. The water intake valve 422 disposed in the conduit 420 connected to the regulator float 162 is now opened to cause water ballast to be added to the regulator float 162. Water is added to the regulator float 162 until the apparatus 10 just starts to sink indicating a negative buoyancy. The water intake valve 422 is immediately closed and the three-way valve 426 moved to the alternate position so that air from the conduit 270 is communicated with the regulator float 162 by way of the conduit 424. The water intake valve 422 is next opened so that the air pressure within the regulator float 160 forces water therefrominto the water intake header and out of the apparatus 10. The valve 422 is allowed to remain open until the apparatus 10 again achieves a positive buoyancy. The apparatus 10 is now ready for submergence and the hydraulic control system 219 should be set up in the manner described above so that the hydraulic jacks 42 and 52 act as dash pots and the buoyancy vessels 28 and 30 are free to move into their uppermost position as the apparatus 10 submerges.

When all preparations for submergence have been completed, the three-way valve 426 is returned to the position whereby the conduit 424 is communicated with the conduit 428 and the water intake valve 422 is opened to allow water ballast to enter the regulator float 162 and bring about the submergence of the apparatus 10. As will be understood, the regulator float 162 is used to control the descent of the apparatus 10 in a desired manner by opening and closing the valve 426.

In moving the apparatus 10 to an offshore location, the buoyancy vessels 28 and 30 are positioned intermediately as illustrated in FIGS. 1 through 4. The removable tie rods 60 are installed between the ends of the vessels 28 and 30 and the ballast tanks 1% and 20 to rigidly hold the vessels 28 and 30 in position while the apparatus 10 is being towed. Towing cables are attached to the lugs 450 attached to the ballast tanks 13 and 20 (FIGS. 3 and 4), and the apparatus 10 is towed on the surface of the water to the location where it is to be submerged. As will be understood, with the buoyancy vessels 28 and 30 at the intermediate position as shown in FIGS. 1 through 4, the center of buoyancy of the apparatus 10 is above the center of gravity thereof and maximum towing stability is obtained. Once the location where the apparatus is to be submerged is reached, the tie bars 60 are removed, the ballast tanks are flooded in the manner described above so that the apparatus l submerges and the buoyancy vessels 28 and 30 are moved to their uppermost position as shown in FIG. 3. When the buoyancy vessels are in the uppermost position, the center of buoyancy is moved to the greatest possible distance above the center of gravity of the apparatus thereby imparting maximum stability to the apparatus while it is submerging. Once the apparatus reaches the bottom of the body of water where it is to be operated, the vessels 28 and 30 are moved to their lowermost position adjacent to the ballast tanks 18 and so that they provide support to the apparatus 10. In order to stabilize the apparatus 10 on the bottom, salt water or other heavier-than-water liquid is pumped into the buoyancy vessels 28 and 30 and ballast tanks 18 and 20.

When it is desired to resurface the apparatus 10 for service or relocation, the ballast contained in the buoyancy vessels 28 and 30 is displaced by compressed air. This can be accomplished by attaching a flexible hose from the hose connector 264 (HO. 7) to connectors on the vessels 28 and 30 (not shown). The buoyancy vessels are allowed to move to their uppermost position, and the water ballast in the regulator float 162 is displaced with air so that the apparatus 10 again obtains a positive buoyancy and surfaces. Once on the surface, the ballast tanks 18 and 20 and the central float 160 are again filled with air to provide maximum buoyancy to the apparatus it).

Thus, the present invention is well adapted to carry out the objects and attain the ends and advantages mentioned as well as those inherent therein. While presently preferred embodiments of the invention have been described for purposes of this disclosure, numerous changes may be made which will readily suggest themselves to those skilled in the art and which are encompassed within the spirit of the invention as defined by the appended claims.

What is claimed is:

l. A submergible apparatus for producing a well beneath the surface of a body of water which comprises:

an oil and gas separator having a well stream inlet, a gas outlet, an oil outlet and a liquid level controller connection disposed therein;

a pair of elongated horizontal ballast tanks attached to said separator;

means attached to the ballast tanks for selectively filling the tanks with water or air thereby providing ballast or buoyancy to said apparatus;

a pair of movable buoyancy vessels attached to the separator and positioned so that the center of buoyancy of said apparatus is above the center of gravity thereof;

means attached to the buoyancy vessels for selectively moving the vessels to alternate positions whereby the distance between the'centers of buoyancy and gravity of said apparatus may be changed to provide maximum stability to said apparatus while being towed on the surface of said body of water or submerged therein;

a removable instrument capsule attached to the separator, said instrument capsule including a liquid level controller connection and oil inlet and outlet connections;

liquid level control means disposed within the capsule for generating a control signal proportional to the variance between the actual liquid level within the separator and the desired liquid level, said liquid level control means being connected to the liquid level controller connection of the capsule;

a conduit removably connecting the liquid level controller connections of the separator and the instrument capsule;

a conduit removably connected between the oil outlet oi' the separator and the oil inlet of the instrument capsule;

valve means responsive to the control signal generated by the liquid level control means for controlling the flow rate of oil removed from the separator and the liquid level maintained therein, said valve means being disposed within the instrument capsule and connected between the oil inlet and outlet connections thereof; and

means for adjusting the liquid level control means with the respect to the desired liquid level to be maintained within the separator from outside the instrument capsule attached to the liquid level control means and to the instrument capsule.

2. The apparatus of claim E which is further characterized to include:

said instrument capsule including a gas inlet connection and a gas outlet connection;

terized to include means attached to said instrument capsule for injecting gas therein and maintaining the pressure thereof at a level above the water pressure level exerted on the capsule thereby preventing water from entering the capsule.

4. The apparatus of claim 3 which is further characterized to include means for dehydrating the gas injected into said instrument capsule disposed within the capsule.

5. The apparatus of claim 4 which is further characterized to include:

said instrument capsule including a well stream inlet connection and a well stream outlet connection; a conduit removably connecting the well stream outlet connection of the capsule to the well stream inlet connection of the separator;

safety shut down control valve means disposed within the capsule and connected between the well stream inlet and outlet connections thereof; and

high level control means for operating said safety shut down control valve means when the liquid level within the separator reaches a preselected high level, said high level control means being responsive to the pneumatic signal generated by the liquid level control means and being disposed within the instrument capsule and operably connected to the safety shut down control valve means.

6. The apparatus of claim 5 which is further characterized to include means for adjusting the high level control means from outside said capsule attached to said capsule and to said high level control means.

7. The apparatus of claim 6 wherein the instrument capsule includes at least one observation port attached thereto so that the instruments contained therein may be observed from outside the' capsule.

8. The apparatus of claim 1 wherein the elongated horizontal ballast tanks are positioned parallel to each other below the oil and gas separator.

9. The apparatus of claim 8 wherein the movable buoyancy vessels are elongated and are positioned on opposite sides of the separator parallel to the ballast tanks, said buoyancy vessels being movable from positions adjacent the ballast tanks to positions above the separator.

10. A submergible apparatus for producing an oil well beneath the surface of a body of water which comprises:

a horizontal oil and gas separator having a well stream inlet, a gas outlet, an oil outlet and a liquid level controller connection disposed therein;

a pair of elongated horizontal'ballast tanks attached to the separator and positioned symmetrically below the separator parallel to the axis thereof;

means attached to the ballast tanks for selectively filling the tanks with water or air thereby providing ballast or buoyancy to said apparatus;

a pair of elongated movable buoyancy vessels attached to opposite sides of the separator positioned parallel to the axis of said separator;

means attached to the buoyancy vessels for selectively moving the vessels from positions adjacent the ballast tanks to positions above the separator so that the distance between the center of buoyancy and the center of gravity of the apparatus may be changed to provide maximum stability to the apparatus when being towed on the surface of said body of water or submerged therein;

closed instrument capsule attached to the separator, said instrument capsule including a liquid level controller connection and oil inlet and outlet connections;

liquid level control means disposed within the cap- 'sule for generating a control signal proportional to the variancebetween the actual liquid level within the separator and the desired liquid level, said liquid level control means being connected to the liquid level controller connection of the capsule;

a conduit removably connecting the liquid level controller connections of the separator and the instrument capsule;

a conduit removably connected between the oil outlet of the separator and the oil inlet of the instrument capsule;

valve means responsive to the control signal generated by the liquid level control means for controlling the flow rate of oil removed from the separator and the liquid level maintained therein, said valve means being disposed within the instrument capsule and connected between the oil inlet and outlet connections thereof; and

means for adjusting the liquid level control means with respect to the desired liquid level to be maintained within the separator from outside the instrument capsule attached to the liquid level control means. and to the instrument capsule.

11. The apparatus of claim 10 which is further characterized to include:

said instrument capsule including a gas inlet connection and a gas outlet connection;

a conduit removably connected between the gas inlet connection of the instrument capsule and the gas outlet connection of the separator;

back pressure control means for controlling the gas pressure within the separator at a desired level disposed within the instrument capsule and connected between the gas inlet and outlet connections thereof; and

means for adjusting the back pressure control means with respect to the desired separator pressure level from outside the instrument capsule and to the back pressure control means.

12. The apparatus of claim 11 which is further characterized to include means attached to said instrument 5 capsule for injecting gas therein and maintaining the 13. The apparatus of claim 12 which is further characterized to include means for dehydrating the gas injected into said instrument capsule disposed within the level within the separator reaches a preselected high level, said high level control means being responsive to the pneumatic signal generated by the liquid level control means and being disposed within the instrument capsule and operably connected to the safety shut down control valve means.

15. The apparatus of claim 14 which is further char acterized to include means for adjusting the high level control means from outside said capsule attached to said capsule and to said high level control means.

16. The apparatus of claim 15 which is further characterized to include shutoff valves disposed in the conduits connecting the instrument capsule to the separa-

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US2767802 *Aug 22, 1955Oct 23, 1956Shell DevUnderwater oil precipitator
US3292695 *Jul 21, 1965Dec 20, 1966Shell Oil CoMethod and apparatus for producing underwater oil fields
US3384169 *May 17, 1966May 21, 1968Mobil Oil CorpUnderwater low temperature separation unit
US3630002 *Mar 24, 1970Dec 28, 1971Combustion EngSeparator control system
US3633667 *Dec 8, 1969Jan 11, 1972Deep Oil Technology IncSubsea wellhead system
US3688473 *Mar 12, 1969Sep 5, 1972Exxon Production Research CoUnderwater oil production separator
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3987638 *Oct 9, 1974Oct 26, 1976Exxon Production Research CompanySubsea structure and method for installing the structure and recovering the structure from the sea floor
US4039025 *Aug 23, 1976Aug 2, 1977Exxon Production Research CompanyApparatus for anchoring an offshore structure
US4506735 *Jun 3, 1983Mar 26, 1985Gerard ChaudotOperating system for increasing the recovery of fluids from a deposit, simplifying production and processing installations, and facilitating operations with enhanced safety
US4615292 *May 14, 1984Oct 7, 1986Laukien Gunther RSubmersible twin-hull watercraft
US4705114 *Dec 19, 1985Nov 10, 1987Texaco LimitedOffshore hydrocarbon production system
US4848475 *Mar 24, 1988Jul 18, 1989The British Petroleum Company P.L.C.Sea bed process complex
US5044440 *Jan 3, 1990Sep 3, 1991Kvaerner Subsea ContractingUnderwater station for pumping a well flow
US6197095 *Feb 16, 1999Mar 6, 2001John C. DitriaSubsea multiphase fluid separating system and method
US6276455 *Sep 24, 1998Aug 21, 2001Shell Offshore Inc.Subsea gas separation system and method for offshore drilling
US6640901 *Aug 18, 2000Nov 4, 2003Alpha Thames Ltd.Retrievable module and operating method suitable for a seabed processing system
US7886829 *Jan 9, 2006Feb 15, 2011David Lindsay EdwardsSubsea tanker hydrocarbon production system
US20080210434 *Jan 9, 2006Sep 4, 2008David Lindsay EdwardsSubsea Tanker Hydrocarbon Production System
WO2009143324A1 *May 21, 2009Nov 26, 2009Rutgers, The State UniversityIron oxyfluoride electrodes for electochemcial energy storage
WO2010144187A1 *May 3, 2010Dec 16, 2010Exxonmobil Upstream Research CompanySubsea hydrocarbon recovery systems and methods
Classifications
U.S. Classification96/113, 166/357
International ClassificationE21B43/34, E21B43/36, B63C11/36, B63C11/00
Cooperative ClassificationE21B43/34, E21B43/36, B63C11/36
European ClassificationE21B43/34, B63C11/36, E21B43/36