CA1036459A - System for operating hydraulic apparatus - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
This invention is directed to a system for operating apparatus which includes hydraulically actuated devices and has provision for cycling the hydraulic fluid continuously in a closed loop from a high pressure side from which the actuated device is energized to a low pressure side which receives hydraulic fluid discharged from the device, and includes a system for repressuring the discharged hydraulic fluid with a gas which may also be recycled in an indepen-dent closed loop, the repressured hydraulic fluid then being continually recycled to function as the energy-transmitting medium in the system. The repressuring portion of the system is arranged for automatic operation. The system is adaptable to the operation of subsea well control apparatus.

Description

1(~36~59 BACKGBOUND QF_THE INVENTION 45 This invention relates to a system for operating, and 48 controlling the operation of, apparatus which uses a hydraulic 49 fluid under pressure as a motive fluid ~or energizing various 50 devices. The invention comprises means for retaining all of 51 the hydraulic fluid ~i~hin the apparatus in an arrangeme~t 52 ~hich permits the fluid to be cycled continuously as the 53 energy-transmitting medium for the selective operation of S4 hydraulically actuated devices in the apparatus. Of particular 56 interest for applications of the present invention are 57 installations whers the apparatus is submerged in a body of 58 ~water and is not readily available for adjustment or repair, and where it is undesirable to permit any of the hydraulic 59 fluid either to be purposely discharged from or to 60 inadvertently escape from the apparatus into the surrounding 61 water.
The arrangement of the apparatus ~hich embodies the 62 invention and the system of its use and control makes it 63 especially suitable for installation as a control means for 64 ~ellhead apparatus, particularly for ~ell control apparatus 65 vhich is submerged in a body of water and affixea to subsea oil 66 wells.
As the oil resources in the deeper waters of the 67 oceans are being aeveloped more consideration is being giYen to 69 procedures for producing wells ~ithout the necessity of erecting fixed platforms at the wellsite. The expense of fixed 71 platforms increases rapidly as the ~ater depth increases, and 72 unless a sufficient number of very productive ~ells can be 73 drilled and produced from a single platform installation, it 75 becomes economically unfeasible to recover the oil at that 76 location. Various proposals haYe been made heretofore to treat 78 subsea ~ells individually, that is, to drill them at their ~9 . 1~36D~S~

respective dispersed locations, to equip each with its own 80 wellhead apparatus, and thsn by pipelines to bring the pro- 82 duction from the individual wells together at a central, fixed a4 offshore platform or to an on-land locationa Some such 85 individual subsea wells have successfully been drilled~ 86 equipped and produced, and the art in this area is continuously 87 devaloping. It is within this environment that the present 89 invention has important significance although it will be 90 appreciated, as the description proceeds hereina~ter, that the 92 inYention has useful application apart from the ~ield af 93 offshore oil recovery.
Subsea systems for controlling the operation of 94 wellhead apparatus, of which I am a~arej now in use in field 96 operations eoploy hydraulic fluid pumps, located either above 97 the surface of the water or incorporated in the submerged 98 apparatus, to provide a supply of power fluid to operate subsea 99 devices. Accumulators for the hydraulic fluid are mounted on 100 the subsea equipment to provide an adjacent reservoir for the 101 pressurized power fluid. When the hydraulic pump is above the 103 surface of the ~ater, these submerged accumulators necessarily 104 are charged through long hydraulic lines, which are exposed to 105 a~mage and the possible lea~age of hydraulic fluid into the 106 ambient water. Additionally, the inherent pressure drop in the 108 long hydraulic lines limits the response of the submerged 109 apparatus when it places a heavy demand on the pressurized 110 fluid supply. Conversely, in those systems where the hydraulic 111 pump is ~ounted directly on the submerged e~uipment, there is a 113 practical limitation on the size of the pump which can be used, 114 since the weight, conformation, compactness, and the area 115 exposed to wave forces are important considerations both from 117 the standpoint of handling and installing the equipment from a 11~
floating vessel and because of the ~ater forces it must resist 120 ~3~459 when it is installed in place. These restrictions on the size of the submerged pump may be such that it is not practical to incorporate in the submerged equipment a pump of adequate size to keep the accumulators continuously charged to working pressure during normal operations.
In either of the foregoing cases, i the demand of the system for power fluid exceeds the rate at which the sub-merged accumulators can be recharged either through the long hydraulic lines from the surface or by the pump incorporated in the submerged equipment, service will be interrupted until the accumulators can be charged to working pressure. Obviously, this is an undesirable circumstance.

SUMM~RY OF THE INVENTION
_ In accordance with one aspect of this invention there is provided means for operating an assembly of apparatus con-taining hydraulically actuated devices comprising: a first chamber and a second chamber in said apparatus; a hydraulic fluid in said chambers; means for selectively increasing and reducing pressure in said chambers individually; a hydraulic fluid actu-ated device in said apparatus; a first conduit means communicat-ing with said device for conducting a pressurized hydraulic fluid thereto for the actuation of said device; a second conduit means communicating with said device for conducting discharged hydraulic fluid therefrom; means for selectively increasing the pressure in the first said chamber to an amount greater than the pressure in the second said chamber to condition said first chamber as a pressure chamber for said hydraulic fluid and to con-dition said second chamber as a receiving chamber for the dis-charged said hydraulic fluid; means operable subsequently to increase the pressure in said second ch-amber while simultane-ously reducing the pressure in said first chamber thereby to condition said second chamber as a pressure chamber for said hydraulic fluid and said first chamber as a receiving chamber for the discharged said hydraulic fluid; and means for selectively ~ ~4-~364~9 connecting said first conduit to the chamber conditioned as said pressure chamber while simultaneously connecting said second Conduit to the chamber conditioned as said receiving chamber to enable said hydraulic fluid to flow from said pressure chamber to actuate said device and thence to flow from said device to said receiving chamber; said chambers and said conduits and said device forming a closed system for retaininy all of said hydraulic fluid within said apparatus during the continued operation there-of.
In accordance with another aspect of this invention there is provided a control system comprising a first chamber and a second chamber with each said chamber constructed to receive and discharge selectively and alternately a hydraulic fluid, a hydraulic fluid in said chambers, a high pressure source of gas for pressurizing said chambers, a first conduit `means communicating with said source, a low pressure reservoir for said gàs, a second conduit means communicating with said low pressure reservoir, a first valve means in said first and said second conduit means for connecting said high pressure source to one of said chambers to condition said one chamber as a high pressure chamber for said hydraulic fluid and for connect-ing said low pressure reservoir to the other said chamber to condition said other chamber as a low pressure chamber for said hydraulic fluid, said first valve means being operable selec-tively and alternately to reverse the said high pressure and said low pressure conditions of each of said chambers, a device actuated by hydraulic fluid in said system, a high pressure conduit means connectable to said device for conducting pressur-ized hydraulic fluid to said device to actuate said device, a low pressure conduit means connectable to said device for conduct-ing discharged said hydraulic fluid away from said device, a second valve means in communication with said high pressure conduit and said low pressure conduit and operable for placing said high pressure conduit in communication with the said one ~, -4a-~36~S9 chamber conditioned as a high pressure chamber and for placing said low pressure conduit in communication with the said other chamber conditioned as a low pressure chamber, and means for operating said first and said second valve means.
In accordance with another aspect of this invention there is provided a control system for a subsea well including submerged hydraulically operated well control devices compris-ing a remotely operated submerged hydraulic fluid system for operating said well control devices, a plurality of chambers in said submerged system, said plurality of chambers including at least one high pressure chamber and at least one low pressure chamber or a hydraulic fluid, a first reservoir of high pressure gas for pressurizing said high pressure chambers, a second reservoir at substantially atmospheric pressure for connection to said low pressure chambers to maintain said low pressure chambers at substantially atmospheric pressure, said first and said second reservoirs located above the surface of said body of .water, respective conduits extending from said reservoir to the submerged said chambers, first valve means in said conduits and located in said submerged system, means for operating said first valve means to place said first reservoir in communication with selected first chambers of said plurality of chambers to condition said selected first chambers to be high pressure chambers for said hydraulic fluids, means for operating said first valve means to place said second reservoir in communication with selected second chambers of said plurality of chambers to condition said selected second chambers to be said low pressure chambers, means for operating said first valve means to reverse the communication of said high pressure reservoir with said plurality of chambers to place said high pressure reservoir in communication with said selected second chambers to condition said second chambers as high pressure chambers and to place said atmospheric pressure reservoir in communication with said selected first chambers to condition said first chambers as low ~ -4b-~(~364S9 pressure chambers, second conduit rneans in said submerged hydrau-lic systems, said second conduit means connecting respective ones of said plurality of chambers with corresponding ones o said well control devices, second valve means in said second conduit means, means for operating said second valve means to connect a respective said high pressure chamber in co~nunication with a corresponding one of said well control device~ to intro-duce energizing said hydraulic fluid to said one device, and to connect a respective said low pressure chamber in communica~
tion with said one device to conduct said hydraulic fluid discharged ~rom said one device to said low pressure chamber, and means for initiating the operating of said first valve means and said second valve means, said submerged hydraulic fluid system forming a closed system for retaining all of the said hydraulic fluid within the said system during the continued operation thereof.
By way of added explanation, an embodiment of the pres-ent invention is designed to provide uninterrupted operation at rapid response rates, and when applied to submerged wells with the required operating hydr~ulic pressures at the submerged wellhead being unaffected by changes in water depth. To accom-pli~sh this, a plurality of hydraulic fluid accumulators are used and are separated into two functionaI portions of the system, one to provide a reservoir of fluid under pressure to energize the hydraulically actuated devices and the other to act as a low-pressure receiver for the hydraulic fluid discharged from the operating devices. The hydraulic portion of the system is a completely self-contained closed loop th~ough which the hydraulic fluid content of the system is continuously recycled and which does not require replenishment during normal operation. When the system is applied to submerged wells, the hydraulic fluid discharged from the exhaust side of the hydrauli-cally operated devices is discharged against substantially atmos-pheric pressure, regardless of the water depth. This latter fea-ture circumvents the necessity for increasing the pressure in the -4c-~36459 energizing side of the hydraulic system as the depth of the 164 water increases, as vould be necessary i~ the hydraulic fluid 165 were discharged against ambient hydrostatic pressure. Thus, 167 the operational parameters of the system are not substantially 168 changed by changes in the depths of water ln which the 169 apparatus may be installed.
In the present system, the accumulator which is 170 functioning as a pressurized chamber for thb hydraulic fluid is 171 charged by a pressurized gas, and the accumulator ~hich is 172 functioning as a receiving chamber for the discharged hydraulic ~73 f~uid is vented by a gas line at substantially atmospheric 174 pressure,. The system is arranged so that the pressurizing gas 175 line and the ~enting line can be connected al~ernately to each 176 of the pressure and receiving accumulators so that ~hen the 177 receiving accumulator becomes filled ~ith discharged hydraulic 178 fluid the pressurized gas line can be connected to it to cause 179 it to function as the pressure chamber while at the same time 180 the venting gas line is connected to what fcrmerly was the 181 pressure accumulator, so that the latter no~ becomes the 182 receiving chamber. Means are provided in the system to make 183 this s~itchover of accumulators automatic ~hen the recei~ing 184 accumulator reaches its filled capacity of hydraulic fluid, so 185 that continuous operation of the system is accomplished without 186 the necessary attention of the human operator. Ho~ever, 188 considering the problems incident to the environment of an 189 offshore oil well in deep ocean waters, it is advisable for 190 such use to build into the system some degree of redundancy 191 such as an alternate provision for manually controlled 192 operation in the event the automatic operating features 193 malfunction.
Sufficient chamher capacity is built into the 194 apparatus to proviae a reasonable amount of continuous 195 ~L~)36~59 operation from the same pressure chamber before the s~itchover 197 of accumulators, as described above, is necessary. This 198 chamber capacity may be provided in single pressure and 199 receiving accumulators, as ~ill be illustrated schematically hereinafter, or the desired chamber capacity may be provided by 201 a plurality of accumulators connected together in groups to unction substantially as the single accumulators illustrated. 202 It is a desirable feature of this invention in 2~3 offshore installations that the medium for providing pressure 205 for pressurizing the hydraulic fluid in the pressure chamber on 206 the energizing side-of the hydraulic system is through a 207 pressure gas line and also that substantially atmospheric 208 pressure is maintained in the receiving chamber through means 209 of a venting gas line. In submerged systems the gas lines can 210 be projected from compressors and gas receivers at the ~ater 211 surface downwardly through the water and connected to the 212 submerged apparatus. Since all of the hydraulic components of 213 the system then are submerged within and usually well belo~ the 214 surface of the water, the chance of hydraulic fluid escaping 215 i~to the ambient water is considerably reduced. The gas lines 217 to the surface pass through the near-surface area, ~here the 218 ~ater forces are the greatest, and thus are more e~posed to 219 damage than are the deeper hydraulic lines. Damage to the gas 220 lines is, o~ course~ undesirable, but does not create the 221 conditon of water contamination, as would occur with a break in 222 a hydraulic line~
Operation of individual valves and devices in the 223 apparatus is controlled remotely from an appropriate consoleY 224 It is understood in the art that a valve may be actuated from a 225 remote location through electrical, hydraulic or pneumatic 226 transmission conduits, or through acoustic or electro-magnetic ~27 radiation signals to initiate actuation of the valve, or by 228 ~364S~
combinations of the foregoing. To simplify the description o~ 229 the system, it will be described hereinafter as including gas 230 transmission conduits for controlling the pressures in the 231 hydraulic fluid accumulators and with electrically operated 232 valves connected to electrical conductors for controlling the 233 valves remotely. It will be understood, however, that the use 234 of these specific elements in the description of the apparatus 235 is by way of example and it is not intended to limit 236 embodiments of the invention thereto. As noted previously, the 238 automatic operation, which is a component feature of a portion 239 of the system, is supplemented by means for manual remote 240 operation as a precaution against compulsory shutdo~n.

BRIEF DESCRIPTION OF_THE_DRAWINGS, 243 FIG. l is a schematic representation of the system of 246 this invention and illustrates the disposition of various of 248 the valves when a particular accumulator is being used as a 249 pressure chamber for pressurized hydraulic fluid and an 250 alternate accumulator is used as a receiving chamber for 2S1 discharged hydraulic fluid~
FIG. 2 is a schematic representation showing the 2~2 dlsposition of the valves in the system when an alternate 253 accumulator is being used as the pressure chamber for 254 pressurized hydraulic fluid and the first accumulator is being 255 used as a recei~ing chamber to receive the discharged hydraulic 256 fluia.
FIG. 3 is a schematic representation of the system of 257 this invention as applied to well control apparatus ~hich 258 contains a pluraiity of hydraulically operated devices. 259 ~IG. 4 is a representation in side elevation of a 260 portion of control apparatus for a submerged ~ellhead and 262 illus~rates a manner of connecting the submerged apparatus to 263 supply lines extending from the water sur~ace.

1~J3f~

~ Ithough this invention can be employed beneficially 268 in a variety of installations, it will be described hereina~ter 269 principally as applied to an offshore well wherein the ~ell 272 control apparatus is secured to a well opening submerged below 273 the surface of a body of water.
The control system illustrated in FIGS. l and 2 can 274 conveniently be divided into three principal subassemblies, as 27S
indicated by the dashed line enclosures numbered respectively 276 10, 12 and 14. The subassembly lO includes a portion of the 277 apparatus vhich may be established at a location spaced apart 278 from the other portions of the system to which it may be 279 operatively connected by appropriate detachable connectors in 280 the gas and electrical lines ~hich are common to the 281 subassemblies. For examplet subassembly lO may be located 282 above the surface of a body of water in ~hich the remainder of 283 the system is submerged as in being connected to a submerged 284 well opening.
Subassembly 12 incIudes the principal assembly of the 285 . . .
valves through which the system is operated. This subassembly 287 may, for example, be encapsulated in a pod vhich can be lowered 288 through the body o~ water and connected automatically in 289 operative relationship to the submerged control devices. 290 Subassembly 14 includes the devices ~hich ultimately 291 are operated by the system and related apparatus such as may be 292 affixed at the submerged location. For example, subassembly 14 294 may include the well control devices such as blowout 295 preventers, which are a component part of the well control 296 apparatus.
In accordance ~ith this invention the well control 297 devices, as represented scbematically by the cylinder and 298 piston arrangement 20 are energized by a pressurized hydraulic 299 ~3~459 fluid. In the posture of the system illustrated in FIG. l, the 301 accumulator Z2 functions as a chamber for the hydraulic fluid 302 under pressure. In the embodiment of the invention as applied 303 to a submerged well, the receiYer 22 preferably is installed as 304 a part of the submerged wellhead apparatus, as illustrated in 305 FIG~ 4. In this location, the pressure chamber is placed 306 immediately adjacent the well control devices operated by 307 hydraulic fluid to eliminate the requirement of running 308 hydraulic lines from the submerged apparatus to the surface of 309 the ~ater. Also, in this posture of the system, the 310 accumulator 24 is connected as the chamber to receive the 311 exhaust hydraulic fluid discharged from the operating well 312 -control device. The accumulator 24 also preferably is located 313 in the submerged wellhead apparatus, as indicated in PIG. 4. 314 As ~ill be explained hereinafter, the accumulators 22 and 24 315 are alternately switched in function to operate at one time as 317 a pressure chamber and at another time as a receiving chamber.
The accumulator 22 is partitioned by a flexible 318 diagram 26 ~hich separates the chamber 28 for hydraulic fluid 319 from a pressurizing gas chamber 30. The gas chamber is in 321 communication ~ith a conduit 32, ~hich is detachably connected 322 through a connector 34, FIG. l, in cOmmuniCatiOD ~ith a conduit 323 36 in tha subassembly 12. The conduit 36 communicates through 324 the valve 38 with a third conduit section 40, which in turn is 32S
in communication with a high-pressure gas receiver 42~ Thus 327 the high-pressure gas is conducted through the conduit arrange-ment described into the gas chamber 30 of accumulator 22 to 328 apply gas pressure to the diaphragm 26 and to place the 32g hydraulic content of the chamber 28 under pressure. Gas 331 receiver 42 has sufficient capacity to exert a substantially constant pressure on the hydraulic fluid in chamber 28 as the 333 , -- 9 _ , ~036~59j fluid volume in the chamber decreases during operation o~ the 334 apparatus.
The second accumulator 24 also is constructed ~ith a 335 flexible diaphragm 44 to separate the hydraulic fluid chambér 336 46 from the gas chamber 48 in a manner similar to that 337 described for the accumulator 22. The gas content of 339 accumulator 24 is in communication with the conduit 50 in 340 subassembly l4. This conduit is placed in communication, 341 through a detachable connector 52, with the conduit 54 in 342 subassembly 12. The latter conduit communicates through valve 343 38 with conduit 56, Nhich i~ turn communicates with a gas 344 receiver 58. Beceiver 58 is constructed with sufficient gas 345 capacity to maintain the gas pressure in the accumulator 24 346 substantially constant as the volume of gas in this accumulator 347 changes ~hile the accumulator is receiving hydraulic fluid. 348 Preferably, in this posture o~ the system the receiver 58 and 350 the gas chamber q8 of the accumulator 24 are maintained at 351 atmospheric pressure.
When accumulator 24 becomes filled with the hydraulic 352 ~luid discharged from device 20t valve 38 is operated to place 353 gas chamber 48 of this accumulator in communication with the 354 pressurized gas receiver 42 and simultaneously to place gas 355 chamber 30 of accumulator 22 in communication with the low- 356 pressure gas receiver S8 in a manner to be described more fully 357 hereinafter. ~hen this s~itchover occurs, chamber 46 of 359 accumulator 24 becomes the reservoir of pressurized hydraulic 360 fluid for operating the system and chamber 28 of accumulator 22 361 becomes the reservoir to receive the discharged hydraulic 362 fluid.
Beferring still to FIG. l, conduit 60 for hydraulic 363 fluid communicates with chamber 28 and is detachably connected 364 .

-~36~59 through a connector 62 with a conduit 64 in subassembly 12. 365 Conduit 64 is connected to a valve 66. 366 A similar hydraulic conduit 68 is in communication 367 with chamber 46 and is connected through detachable connector 368 70 ~ith a complementary conduit 72 in subassembly 12. Conduit 370 72 also is connected to valve 66.
In the posture of the system illust,rated in PIG. 1, 371 the pressurized hydraulic fluid fro~ chamber 28 passes through 372 valve 66 into conduit 74, ~hich latter leads to a third valve 374 76 and to a fourth valve 78. The hydraulic fluid discharged 375 from the opera~ing device 20 subsequently passes through 376 conduit 80 and through valve 66 ana thence to receiving cha~ber 377 46 in a ~anner to be described in more detail hereina~ter.
Valve 76 in subassembly 12 directly con~rols the 378 operation of the hydraulically operated device 20. ~hus, in 380 the position of this valve i~dicated in FIG. 1, the pressurized 381 hydraulic fluid passes from conduit 74 through valve 76 and 382 into conduit 82 in communication with the valve. Conduit 82 is 383 detachably connected through connector 84 to complementary 384 conduit 86 in subasse~bly 14.
Hydraulically operated device 20 is indicated as a 386 cylinder-and-piston arrangement, although obviously other forms 387 of hydraulically operated devices may be employed in this system. The aforementioned conduit 86, which in the present 388 instance carries pressurized hydraulic fluid to energize the 389 hydraulically operated device, communicates with one end of 390 cylinder 20. Second conduit 88 communicates ~ith the other end 392 of the cylinder. As ~ill be understoad in the art, the 394 pressurized hydraulic fluid enters one end of the cylinder and 395 pushes the piston toward the other end. As the piston moves it 397 displaces hydraulic fluid which is exhausted or' discharged from 398 the cylinder through conduit 88. This conduit is connected 399 1~36~Sg through detachable connector 90 Hith conduit 92 in subassembly 400 12, ~hich latter conduit i5 in communication with valve 76. 401 The discharged hydraulic fluid flows through valve 76 into 403 conduit 80 and thence through valve 66 into the connected 404 conduits 72 and 68 and into the hydraulic fluid chamber of 405 accumulator 24.
The arrangement and integrated operation of the 406 valves in the subassembly 12 is such that conduit 80 Hill 407 al~ays be connected in the hydraulic fluid circuit to carry 408 discharged hydraulic fluid away from the hydraulically operated 409 devices toward the appropriate receiving accumulator. 410 Pressure-sensitive device 94 is in communication ~i~h conduit 411 80 and is connected in the system to operate simultaneously 412 valves 38 and 66. For example, if valves 38 and 66 are 414 operated by electrically energized solenoids, a pressure- 415 activated electrical s~itch may be used in the device 94 to 4~6 direct an electrical current to each of the valves 417 simultaneously to cause each valve to be changed to an 418 alternate position.
As explained hereto~ore, the conduit 80 is arranged 419 in respect to the valves in communication with it to conduct 420 discharged hydraulic fluid to the selected receiving chamber. 421 When the hydraulic fluid receiving chamber is filled to 422 capacity, as illustrated by chamber 46 in accumulator 24 ~hen 423 progressing from FIG. l to FIG. 2, the hydraulic prassure in 424 the interconnected conduits 68, 72 and 80 ~ill increase as more 425 discharged fluid is directed toward the receiving accumulator. 426 ~he pressure-sensitive device 94 is arranged to be activated by 427 a predetermined increase in pressure in conduit 80 to energize 428 the val~es 38 and 66 to cause them to change position. The 430 system then assumes the posture illustrated in FIG. 2.

~ 12 ~ r - \

~3~59 Referring to FIG. 2, the hydraulic fluid chamber 46 431 in accumulator 24 is represented as being filled to capacity. 432 The resulting increase in pressure in conduit ~0 has caused the 433 pressure-sensitive device 94 ~o actuate valve 38 to place the 435 pressurized gas receiver 42 in communication with the gas chamber 48 through the interconnected conduits 40, 54 and 50 436 At the same time~ and through the same valve, the gas chamber 437 30 in accu~ulator 22 has been placed in co~munication ~ith the 439 atmospheric pressure gas receiver 58 through the inter-communicating conduits 56, 36 and 32. Simultaneously, the 441 pressure-sensitive device 94 has activated valve 66 to place 442 the conduit 74 in communication with the interconnected 443 conduits 68 and 72, which latter no~ contain pressurized hydraulic fluid from chamber 46, and to place the conduit 80 in 445 communication with the interconnected conduits 60 and 64 which 446 lead to the hydraulic fluid chamber of accumulator 22. Thus, 448 the functions of the t~o accumulators are switched and the 449 first accumulator, which formerly contained the reservoir for 450 pressurized hydraulic fluid, now becomes the receiving chamber, 451 while the second accumulator, which formerly contained the 4S2 receiving chamber, no~ becomes the reservoir for pressurized 453 hydraulic fluid.
It ~ill be noted that the switchover of functions of 455 the accumulators through the automatic operation of the 456 pressure-sensitive device 94 maintains the conduit 74 as a 457 pressure-fluid carrying conduit and, as noted previously, 458 conauit 80 is maintained as the discharged-fluid-carrying conduit. Thus, ~hen the functions of accumulators 22 and 24 460 are exchanged val~e 76 remains in its original position to 461 direct the energizing, pressurized hydraulic fluid through the 462 interconnected conduits 82 and 86 to consistently power the 463 device 20 in the chosen direction. By this invention the 465 :~3~S9 functions of the accumulators 22 and 24 are switched automatically to provide a continuous supply of energizing 466 hydraulic fluid to the operating device 20 without adversely 467 affecting the operation of the latter. 468 Various valves in the vellhead apparatus are arranyed 470 to be activated by an appropriate signal sent ~rom a remote 471 location. By way of example, the valve 76 is c~nnected to a 473 console 96 in subassembly lO through a signal-transmitting line 474 98. The console contains a plurality of separate stations, as 475 represented schematically by the buttons lO0, each o~ which can 476 control the operation of a particular device in the submerged 477 apparatus. The signal-transmitting line 98 may be a 478 multiplexed system using a single pair of conductors to 479 transmit the signals or a cable containing separate lines to 481 each device, as will be understood in the art~ A signal- 482 generating means, such as a source of electrical power, is provided in subassembly lO, to provide a signal ~hich is 483 transmitted through line 98 to energi~e a selected unit in the 484 assembly,such as the valve 76, and position it in a manner to 486 cause the desired operation of the apparatus. ~or example, if 487 device 20 is a piston-actuated blowout preventer and valve 76 488 is positioned as illustrated in FIGS. l and 2, the blo~out preventer ~ill be powered to a closed condition. To open the 490 blowout preventer, valve 76 is operated to place the pressurized fluid conduit 74 in communication ~ith conduit 92 491 and the discharged fluid conduit 80 in communication with the 492 conduit 82~ Thus, the energizing pressurized hydraulic f~uid 494 ~ill enter cylinder 20 at the appropriate end to po~er the 495 piston in the direction to open the blowout preventer and the 496 hydraulic fluia in the other end of the cylinder ~ill be 497 discharged through conduits 86 and 82 and through valve 76 into 498 conduit 80~

1~364S~

The portion of the hydraulic circuit in subassembly 499 12 has included in it a valve 78 which also is connec~ed 500 through a signal-~ransmitting means to console 96. In the 502 position of the valve illustrated in FIG. 1, the conduit 102, ~hich is an extension of the pressurized hydraulic fluid 503 conduit 74 is dead-ended in the valve. However, this valve may 505 be operated upon a signal from console 96 to place the 506 :discharged hydraulic fluid conduit 80 in communication with the 507 pressure hydraulic fluid conduit 102, as indicated by the 508 :dotted line 104 in PIG. 1. This position of valve 78 provides 509 a bypass ~or the hydraulic fluid and permits the fluid to flo~ 510 from the pressurized chamber, ~hich would be the hydraulic 511 fluid chamber in accumulator 22 in the instance of FIG. 1 512 through valve 66 and valve 78 into conduit 80 and again through 513 valve 66 and into interconnecte.d.conduits ~2 and 68 and thence 514 lnto hydraulic fluid receiving chamber of accumulator 24. 515 Valve 78 is provided primarily to permit one of the 516 accumulators to be filled ~ith hydraulic fluid and the other to 517 be emptied at the start of operations of the entire system, or 518 to permit the system to be placed in this desired condition of 519 operation after a shutdo~n or other delay ~hich occurred when 520 ~:both chambers ~ere partly filled with hydraulic fluid. 521 Desirably an auxiliary chamber, preferably in the 522 form of an accumulator 106 ~hich has a flexible diaphragm 108 523 divlding it i~to a hydraulic fluid-containing chamber 104 and a 524 gas-containing chamber 110 is provided in the system. 525 Hydraulic ~luid chamber 104 is placed in communication with the 526 discharge fluid conduit 80 and gas chamber 110 is placad in 527 communication through conduit 112 with the vent line 56 to the 528 atmospheric pressure gas recei~er 58. The auxiliary chamber is 530 placed in the system to function as an expansion chamber for 531 the hydraulic fluid and to assist in maintaining the pressure 532 " .

1~3~;~59 in the discharse fluid conduit 80 substantially at atmospheric 533 pressure, and also to provide some make-up fluid if the 534 hydraulic system requires it.
In the system illustrated in PIGS. 1 and 2, the 535 pressurized gas receiver 42 is connected to a compressor 114 536 which draws the gas ~rom the lo~-pressure receiver 58. Thus, 538 the pressurizing gas portion of the assembly also may be a 539 closed system. Pre~erably, the compressor 114 is selected Yith 540 a capacity to maintain the receiver 58 at substantially 541 atmospheric pressure. ~lowever, if de$ired~ the low-pressure 543 side of the system can be operated at a pressure other than 544 atmospheric, either at a greater or lesser pressure. The 546 relative difference in pressure of the two receivers determines the pressure differential imposed by the hydraulic fluid across 547 the operating device, as 20, and offers further control of the 548 system.
~ s described heretofore, desirably, each of the 549 valves and the pressure sensitive device 94 in subassembly 12 550 is connected to the control console in subassembly 10 by 551 complementary signal-transmitting means, such as by electrical 552 conductors. This permits the system to be operated manually as 553 well as automatically and provides a means for continuing the 554 opera~ing of the system if the automatic features of it such,as 556 the pressure sensitive device 94, should malfunction. In some 558 installations, as in the offshore environment, it may be 559 desirable to gather the gas lines and the electrical lines extending between subassemblies 10 and 12 into a single bundle 561 to assist in handling these lines and preventing their becoming 562 entangled with each other or the submerged apparatus. This 564 bundle is indicated by the dotted circle 116 in FIGS. 1 and 2 and by the same numeral in FIG. 4. 565 .

- ~6 -i~?36~Sg Referring now to FIG. 3, the system of this invention 566 is illustrated diagramatically as applied to a particular 567 arrangement of well control apparatus. Similar apparatus as 569 applied to a submerged ~ell is schematically illustrated in 570 FIG. 4 ~hich further illustrates a feature to ~hich this 571 invention can be adapted for offshore operations. To 573 illustrate this environment the numeral 117, FIG~ 3~ indicates the surface of a body of water ll9 in which the wellhead is 574 submerged.
The arrangement of devices indicated in subassembly 575 14 of FIG. 3 and by FIG. 4 is commonly kno~n as a blo~out 576 preventer (BOP) stack and is secured to the ~ell opening during 577 the time the vell is being drilled and through some stages of 578 its completion. When the well is completed a different 579 arrangement of devices, called a "Christmas tree", is secured 580 to the opening of the ~ell casing, as is known in the art. The 582 system of the present invention can be applied to operate the 583 cpntrol de~ices of a Christmas tree and other assemblages of 584 apparatus, and the application of the invention to the installation represented in FIGS. 3 and 4 is merely 585 illustrative, and it is not intended to limit the application 586 of t~is invention to such an arrangement. 587 A BOP stack normally comprises a series of vertically 588 interconnected BOP's of different types, which can be operated 589 independently of each other to control the ~ell opening as 590 circumstances require~ In the apparatus illustrated in the 592 dra~ings, the numeral 118 represents a bag-type BOP and the 593 numerals 120, 122, 124 and l26 represent respective ram-type 594 BOP's. The numerals 128 and 130 indicate elements of an 596 assemblage made principally for offshore operations and 597 represent hydraulically po~ered connectors, the connector 130 598 being used to detachably connect the BOP stack to the ~ell 599 ~36~59~

casing and the connector 128 being used to detachably connect a 600 marine riser 132 to the top of the BOP stack in a manner known 601 to the art. It will be appreciated that not all o~ the devices 602 indicated in the drawings need necessarily be included in the 603 assemblage as represented to be ~ithin the purview of this 604 invention and more or less, or different, forms of operating 605 units may be assembled as the situation reguires without 606 departing from the inventive concept. 607 ~s stated heretofore, it is desirable that each of 608 the hydraulically operated devices in the well head assemblage 609 is selectively operable independently of the others. To this 611 end, each device has associated with it a respective valve hy 612 which to control the hydraulic fluid circuit to lt. Thus, for 614 each of the operating u~its included in the assembly of apparatus indicated in subassembly 14 of ~IG. 3, there is a 615 control valve in subassembly 12. The valves ~hich control the 617 connectors and the BOP~s of the ~ellhead apparatus, such as 618 valYes 134 and 136, may be similar in form and function to the 619 previously described valve 76.
In FIG. 3, the accumulator 24 is functioning as the 621 pressure chamber and accumulator 22 is the receiving chamber.
The conduit 74 carrying pressurized hydraulic fluid to the 622 various control valves takes the form of a manifold 138 from 623 ~hich individual branch conduits, as 140 and 142, lead to the 624 respective control valves, as 134 and 136. The conduit 80, 626 ~hich carries the discharged hydraulic fluid away from the 627 operating devices, also takes the form of a manifold 144, which 628 is connected by individual branch conduits to respective val~es as indicated by conduits 146 and 148 connected to respective 630 valves 134 and 136. The individual control valves are, of 631 course, connected to the respective hydraulical~y actuated 632 devices through corresponding interconnected conduits, such as 633 3~L5~
conduits 150 and 152 for the pressure line of the hydraulic 634 actuator 153 of connector device 130 and interconnected 635 conduits 1~4 and 156 for the return line for discharged 636 hydraulic fluid.
The well control system illustrated in PI~. 3 637 includes kill valve 158 and bleed valve 160, the use ~f ~hich 63~
is ~ell kno~n in the art. Each o~ these valves has a 640 respective control valve in subassembly 12, as 162 and 164, 641 which is connected to the pressure fluid and discharge fluid 642 manifolds 138 and 144. The kill and bleed valves illustrated 643 are spring-biased to a closed position. Hence, only a single 645 hydraulic fluid conduit is required for each, as represented by 646 the interconnected conduits 166 and 168 for valve 15~. The 648 corresponding control valves 162 and 164 are arrange2 to be positioned to introduce a pressurized hydraulic fluid into the 649 corresponding conduits to open the kill or bleed valve or 650 alternatively to be positioned to connect the same 651 corresponding conduit with the discharge manifold to release 652 pressure from the kill or bleed valve to cause it to close as 653 valve operation requires. The Ullit 170 in subassembly 12 of 654 FIG. 3 represents a pressure reducing valve for controlling the 655 pressure in the bag-type BOP 118. 656 As described in relation to FIG. 1, all of the 657 conduits interconnecting subassembly 12 and subassembly I4 may 658 be connected together by detachable connectors which permit 659 the subassemblies to be connected to and disconnected from each 660 other in operating relationship. For working in submerged 662 wells the detachable connectors may be operated fro~ a remote 663 ~ocation as from the surface of the water, without requiring 664 diver assistance. ~y this arrangement, all of the control 665 valves and the co~ponent portions of the hydraulic and 666 electrical circuits, and including pressure-responsive device 667 94, may be incorporated in a pod 172 as illustrated in FIG. 4. 668 The pod is arranged to be lowered from the surface of the ~ater 669 into engagement vith a pod receiver 174~ ~ach of the 671 appropriate hydraulic lines in the pod is in communcation with 672 a corresponding connector portion as 176 which mates ~ith a 673 complementary connector portion 178 on the pod receiver, which 674 latter portion is in communication with the appropriate hydraulic conduit as, or example, conduit 50 on the ~ellhead 675 control apparatus, which latter corresponds to subassembly 14. 676 Hhere required, electrical connection can be made bet~een the 677 two subassemblies in a similar manner. It ~ill be appreciated 679 also that a system of detachable connectors may be used to 680 interconnect the conduits and signal lines betveen 68 subassemblies 10 and 12.
Various conduits connected to the pod receiver 174 682 are schematically indicated in FIG. 4~ The conduits are 684 ~athered together in a bundle 180 or other~ise neatly arranged 68 on the ~ellhead apparatus and the individual conduits are directed to the hydraulically operated devices to which they 686 pertain as schematically illustrated by the lines 50 and 68 to 687 accumulator 24, all o~ which is kno~n to the art. The cable 689 bundle 116 contains the gas lines and electrical lines, where applicable, connecting the pod with the surface console 96 and 690 gas receivers 42 and 58, as has been mentioned heretofore. The 692 cable bundle also contains the stress cable 182 by ~hich the 693 pod is raised and lowered through the ~ater.
Because of the particular problems inherent in the 694 offshore environment, it is advisable to provide duplicate pods 696 172, duplicate pod holders 174, and duplicate hydraulic 697 circuitry 180 to afford a better chance for continued operation 698 should a malfunction occur in one of the pod assemblies. This 699 redundancy of equipment is familiar to the art, and hence it is 700 1~36~9 not necessary for the present teaching to describe it in more 701detail~
As described with relation to valve 76 of FIG~ 1, 702 each of the control valves, as represented by way o~ example by 703 valves 134 and 136 and 170 of FI~. 3, is controllable by an 704 actuating signal from a remote location. Thus, the valYes may 707 be connected through individual electrical conductors ~ith the control console 96 at the surface of the ~ater so that, in 708 addition to the automatic operation built into the system as 709 described heretofore, each of the hydraulically operated 710 devices in the wellhead equipment can be controlled manually 711 independently of the other devices~
It is apparent that equivalents may be substituted 712 for the particular elements described heretofore, ana cther 713 modifications may be made to the system illustrated as a 714 preferred embodiment ~ithout departing from the inventive 715 concept, and it is intended that the invention encompass such 716 e~uivalents and modifications within the scope of the appended 717 claims.

Claims (15)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. Means for operating an assembly of apparatus containing hydraulically actuated devices comprising:
a first chamber and a second chamber in said apparatus;
a hydraulic fluid in said chambers;
means for selectively increasing and reducing pressure in said chambers individually;
a hydraulic fluid actuated device in said apparatus;
a first conduit means communicating with said device for conducting a pressurized hydraulic fluid thereto for the actuation of said device;
a second conduit means communicating with said device for conducting discharged hydraulic fluid therefrom;
means for selectively increasing the pressure in the first said chamber to an amount greater than the pressure in the second said chamber to condition said first chamber as a pressure chamber for said hydraulic fluid and to condition said second chamber as a receiving chamber for the discharged said hydraulic fluid;
means operable subsequently to increase the pressure in said second chamber while simultaneously reducing the pressure in said first chamber thereby to condition said second chamber as a pressure chamber for said hydraulic fluid and said first chamber as a receiving chamber for the discharged said hydraulic fluid; and means for selectively connecting said first conduit to the chamber conditioned as said pressure chamber while simultaneously connecting said second conduit to the chamber conditioned as said receiving chamber to enable said hydraulic fluid to flow from said pressure chamber to actuate said device and thence to flow from said device to said receiving chamber;
said chambers and said conduits and said device forming a closed system for retaining all of said hydraulic fluid within said apparatus during the continued operation thereof.

2. Means in accordance with Claim 1, wherein said hydraulic fluid operated device comprises a plurality of discrete hydraulic fluid operated units, and wherein said discrete units have operatively connected thereto respective complementary said first and said second conduit means, respective valve means in said respective complementary conduit means, and means for operating a said respective valve means independently of other said respective valve means to operate a selected said discrete unit independently of other said discrete units, means for operating said plurality of discrete units by hydraulic fluid from a common said pressure chamber, and means for conveying said discharged hydraulic fluid from said plurality of units to a common said receiving chamber.

3. Means in accordance with Claim 2 including:
means for maintaining the pressure in said common pressure chamber at a substantially constant amount of the increased pressure;
and means for maintaining the pressure in said common receiving chamber at a substantially constant amount of the reduced pressure;

while units of said plurality of discrete units are being operated.

4. Means in accordance with Claim 3 wherein:
the pressure in said common receiving chamber is maintained at substantially atmospheric pressure.

5. Means for operating apparatus in accordance with Claim 1 wherein said means operable subsequently to increase the pressure in said second chamber while simultaneously reducing the pressure in said first chamber comprises a pressure activated device associated with the said receiving chamber, means operatively connected to said pressure activated device and operative to increase the pressure in one of said chambers while simultaneously reducing the pressure in the other said chamber, said pressure activated device operating when the pressure in said receiving chamber exceeds a preselected amount to cause the pressure in said receiving chamber to be increased to condition said receiving chamber to become a subsequent said pressure chamber and simultaneously to cause the pressure in said pressure chamber to be reduced to condition said pressure chamber to become a subsequent said receiving chamber.

6. Means for operating apparatus in accordance with Claim 1 including a pressurizing gas for placing pressure in said pressure chamber, a pressure activated device associated with the said receiving chamber in operative relationship, valve means for directing said pressurizing gas to one of said chambers and for releasing said pressurizing gas from the other said chamber, means connecting said pressure activated device and said valve means in operative relationship, said pressure activated device being arranged to operate said valve means when the pressure in the chamber conditioned as a said receiving chamber exceeds a preselected amount, said valve means operating to direct said pressurizing gas to said receiving chamber to condition said receiving chamber as a subsequent said pressure chamber and to release said gas from said pressure chamber to condition said pressure chamber as a subsequent said receiving chamber.

7. Means for operating apparatus in accordance with Claim 6 including, a high pressure gas receiver and a low pressure gas receiver, said high pressure gas receiver comprising said means for placing pressure in said pressure chamber, means for selectively operably connecting said high pressure gas receiver alternatively and sequentially to one of said first and said second chambers to condition said one chamber as a said pressure chamber while simultaneously operably connecting said low pressure gas receiver to the other said chamber to condition said other chamber as a said receiving chamber.

8. Means in accordance with Claim 7 wherein said apparatus is positioned at a body of water, said gas receivers are located above the surface of said body of water and a substantial portion of said apparatus including said chambers is submerged below the surface of said water, respective conduit means connecting said gas receivers with said chambers in said submerged apparatus, valve means in said respective conduit means, and means for operating said valve means automatically to selectively place the said respective conduit means in communication alternatively with selected said chambers.

9. Apparatus in accordance with Claim 2 wherein said units and said respective valve means and said means for operating said respective valve means are submerged in a body of water, a remote control means for controlling the operation of said means for operating said respective valve means, said remote control means being located above the surface of said body of water, and means for transmitting a controlling signal from said remote control means to said submerged apparatus to initiate the operation of a said respective valve means.

10. A control system comprising a first chamber and a second chamber with each said chamber constructed to receive and discharge selectively and alternately a hydraulic fluid, a hydraulic fluid in said chambers, a high pressure source of gas for pressurizing said chambers, a first conduit means communicating with said source, a low pressure reservoir for said gas, a second conduit means communicating with said low pressure reservoir, a first valve means in said first and said second conduit means for connecting said high pressure source to one of said chambers to condition said one chamber as a high pressure chamber for said hydraulic fluid and for connecting said low pressure reservoir to the other said chamber to condition said other chamber as a low pressure chamber for said hydraulic fluid, said first valve means being operable selectively and alternately to reverse the said high pressure and said low pressure conditions of each of said chambers, a device actuated by hydraulic fluid in said system, a high pressure conduit means connectable to said device for conducting pressurized hydraulic fluid to said device to actuate said device, a low pressure conduit means connectable to said device for conducting discharged said hydraulic fluid away from said device, a second valve means in communication with said high pressure conduit and said low pressure conduit and operable for placing said high pressure conduit in communication with the said one chamber conditioned as a high pressure chamber and for placing said low pressure conduit in communication with the said other chamber conditioned as a low pressure chamber, and means for operating said first and said second valve means.

11. A control system in accordance with Claim 10 including means responsive to a predetermined increase in pressure in said low pressure conduit for automatically initiating operation of said first and said second valve means.

12. A control system in accordance with Claim 10 wherein said control system is a system for controlling the operation of apparatus on a submerged well and said device is positioned at the submerged wellhead including said source of pressurizing gas and said low pressure reservoir located above the surface of said water, said first and said second conduit means extending from respectively the said source of pressurizing gas and said low pressure reservoir through the said body of water to the submerged apparatus, a signal-generating means located above the surface of said water for controlling the operation of said system remotely, and means for transmitting a controlling signal from said signal-generating means to the submerged apparatus to energize the said submerged device.

13. A control system for a subsea well including submerged hydraulically operated well control devices comprising a remotely operated submerged hydraulic fluid system for operating said well control devices, a plurality of chambers in said submerged system, said plurality of chambers including at least one high pressure chamber and at least one low pressure chamber for a hydraulic fluid, a first reservoir of high pressure gas for pressurizing said high pressure chambers, a second reservoir at substantially atmospheric pressure for connection to said low pressure chambers to maintain said low pressure chambers at substantially atmospheric pressure, said first and said second reservoirs located above the surface of said body of water, respective conduits extending from said reservoir to the submerged said chambers, first valve means in said conduits and located in said submerged system, means for operating said first valve means to place said first reservoir in communication with selected first chambers of said plurality of chambers to condition said selected first chambers to be high pressure chambers for said hydraulic fluids, means for operating said first valve means to place said-second reservoir in communication with selected second chambers of said plurality of chambers to condition said selected second chambers to be said low pressure chambers, means for operating said first valve means to reverse the communication of said high pressure reservoir with said plurality of chambers to place said high pressure reservoir in communication with said selected second chambers to condition said second chambers as high pressure chambers and to place said atmospheric pressure reservoir in communication with said selected first chambers to condition said first chambers as low pressure chambers, second conduit means in said submerged hydraulic systems, said second conduit means connecting respective ones of said plurality of chambers with corresponding ones of said well control devices, second valve means in said second conduit means, means for operating said second valve means to connect a respective said high pressure chamber in communication with a corresponding one of said well control devices to introduce energizing said hydraulic fluid to said one device, and to connect a respective said low pressure chamber in communication with said one device to conduct said hydraulic fluid discharged from said one device to said low pressure chamber, and means for initiating the operating of said first valve means and said second valve means, said submerged hydraulic fluid system forming a closed system for retaining all of the said hydraulic fluid within the said system during the continued operation thereof.

14. A control system in accordance with Claim 13 including means for positioning said initiating means above the surface of said body of water, and means for transmitting a control signal from said initiating means to said submerged system.

15. A control system in accordance with Claim 13 including a pressure sensitive device in communication with said low pressure chambers, means operatively connecting said pressure sensitive device to said first and said second valve means, said pressure sensitive device being arranged to be actuated at a predetermined pressure to initiate the operation of said first and said second valve means to reverse the communication of said high pressure and said atmospheric pressure reservoirs with the respective said chambers and to reverse the communication of said high pressure chamber and said low pressure chamber with said one device.