US3338302A

US3338302A - Control system for sub-sea apparatus

Info

Publication number: US3338302A
Application number: US391541A
Authority: US
Inventors: Laurence M Hubby
Original assignee: Texaco Inc
Current assignee: Texaco Inc
Priority date: 1964-08-24
Filing date: 1964-08-24
Publication date: 1967-08-29
Anticipated expiration: 1984-08-29

Description

1967 M. HUBBY CONTROL SYSTEM FOR SUB-SEA APPARATUS 2 Sheets-Sheet 1 Filed Aug. 24, 1964 wm QSQ QW Aug. 29, 1967 L. M. HUBBY 3,338,302

CONTROL SYSTEM FOR SUB-SEA APPARATUS Filed Aug. 24, 1964 2 Sheets-Sheet 2 BOP I 3 E 5 4 2 i Z 2 7 United States Patent 3,338,302 CONTROL SYSTEM FOR SUB-SEA APPARATUS Laurence M. Hubby, Bellaire, Tex., assignor to Texaco Inc., New York, N.Y., a corporation of Delaware Filed Aug. 24, 1964, Ser. No. 391,541 3 Claims. (Cl. 166-.5)

ABSTRACT OF THE DISCLOSURE Apparatus for operating blow-out preventers and such underwater wherein operating fluid is supplied from an underwater storage vessel in response to activation from the surface and fluid in the underwater storage vessel is automatically replenished from another fluid storage vessel located at the surface.

This invention relates to a control system and, more particularly, to a remotely operated control system which provides fluid under high pressure for operating apparatus located in deep water.

It is necessary in connection with deep water well drilling or producing operations to provide safety apparatus to shut off the well which is positive in action, fast acting and which is operable from a surface location. The necessity of such equipment can be appreciated not only because of the extreme pressures which may be suddenly released during drilling of the well but also in connection with the necessity of shutting off the well because of surface conditions such as violent storms. This is especially important in connection with floating drilling rigs which must shut down the well when it is necessary to temporarily abandon the position. In such an event, all the surface equipment is disconnected from the sub-sea elements and the only remaining portions are the sub-sea well head which has mounted thereon the blowout preventers. This equipment being located at the bottom of the body of water is, as can be readily realized, safe from damage by the storm and does not present a hazard to navigation.

The usual arrangement for providing control or shut-off of the well is by means of blowout preventers which are operated by fluid pressure provided thru control lines descending from the floating rig. The disadvantage of this arrangement is that the control lines must necessarily be of a small diameter to withstand the high pressures which are required to operate the blowout preventers. The blowout preventers themselves require a large volume of fluid for operation and therefore cause a large pressure dro across the control line. In order to overcome this large pressure drop because of the large amount of fluid required, additional control lines have been added in parallel in the past.

It has been known to utilize the sea water itself as the pressure conveying fluid to operate the blowout preventers in what is commonly referred to as an open pressure system. However, such a system produces corrosion and sticking of the blowout preventers so that it is unreliable in operation.

Accordingly, it is the main object of the present invention to provide a hydraulic control system for operating well shut-off apparatus on a sub-sea well positively and quickly without encountering the above-mentioned disadvantages.

It is another object of the present invention to provide a well shut-off apparatus control system in which all electrical equipment is provided above the water level for safety and accessibility.

It is a further object of the invention to provide a control system for operating well shut-off apparatus quickly and positively which utilizes fluid in a closed system.

It is another object of the invention to provide a control system for operating well shut-off apparatus wherein the working parts are protected from corrosion and sticking.

Briefly stated, applicants invention comprises a control system for operating Well shut-ofl. apparatus located under water at the Well head which consists of a pressurized sub-sea fluid storage vessel located adjacent the well shutoff apparatus for providing fluid under pressure for operation thereof. Valves, which are controlled from remote points above the water surface, are provided in the piping between the sub-surface storage vessel and the well shutoff apparatus. A fluid sump is also provided adjacent the well head and connected to the well shut-off apparatus to receive the fluid displaced therefrom upon operation. A surface-located recharging means is provided for recharging the pressurized sub-surface storage vessel after operation of the well shut-off apparatus. A recycling means is also provided for transferring the fluid accumulated in the sub-sea sump as a result of an operation of the well shut-off apparatus to a surface located sump means which is joined to said recharging means thereby conditioning the system for a further operation of the blowout preventers.

The foregoing and other features and benefits of this invention are described below in greater detail and are illustrated in the drawings, in which:

FIG. 1 is a schematic flow diagram of the control system showing the necessary control tubing and piping between the control system components.

FIG. 2 is a schematic vertical section of a two-position four way control valve.

FIG. 3 is a schematic vertical view showing the locations of the sub-sea components of the control system with respect to the sub-sea well head.

FIG. 4 is a plan view of the sub-sea components of the control system shown in FIG. 3.

The fluid used in the control system described herein is hydraulic fluid such as oil which not only conveys the pressures applied thereto but also serves as a preservative and a lubricant to minimize sticking and thereby increase the reliability of operation. It will be appreciated that other fluids may be used such as certain gases and still fall within the scope of the instant invention.

12 and 13. A further blowout preventer 14 is shown schematically in dotted line form to indicate that further blowout preventers can be included in addition to the other blowout preventers and can be adequately controlled by adding the necessary valves in the control system to take care of each additional blowout preventer. Blowout preventers are well known in the oil Well drilling industry and are usually connected at the well head to the top of the deepest string of pipe which has been set and cemented in the well. The preventers are equipped with rams or equivalent elements which can be operated to seal the annular space between the drill pipe and the string of casing to which the blowout preventer is attached.

The underwater storage vessel 21 is located at the bottom of the body of water adjacent the well head and is connected to the blowout preventers 12 and 13 by means of piping 22. This underwater storage vessel contains a gas such as nitrogen trapped therein which is pressurized by the fluid in the system. The nitrogen is maintained under a pressure of approximately 2500 p.s.i. which is considered an adequate pressure to operate the blowout preventers. Inserted in the piping 22 are valves 23 and 24 for providing control of the operation of the blowout preventers 12 and 13, respectively. These valves are twoposition four-way pilot controlled valves. As can be seen more clearly from FIG. 2, these valves have, in each of two positions, two distinct paths therethrough in which the fluid may be forced in either direction. The valves are shown operated by pistons which are, in turn, controlled by manually operated valves 27 and 28 at the surface. Surface valves 27 and 28 are also of the twoposition four-way type, a cross-section of which would look like FIG. 2. A variety of four-Way valves exist in the art, any one of which could be adapted for use in the present control system. Accordingly, a detailed explanation of the valves is not believed to be warranted. The surface valves 27 and 28 are shown connected to the underwater control valves 23 and 24 by flexible tubing 31, 32 and 33, 34, respectively. The surface valves 27 and 28 are connected via conduit 37 to a pressurized surge chamber 41. The surge chamber is pressurized only to 150 p.s.i. since the fluid pressure is only required to operate the valves. Thus, the tubing 31, 32 and 33, 34 running from the surface to the sub-surface equipment is not subjected to high pressures. The valves are also connected to surface sump tank 51 via common conduit 35. The common conduit 35 carries the fluid displaced by any operation of the pistons of valves 23 and 24 to the sump tank 51.

The blowout preventers when operated displace considerable fluid which is fed to an underwater sump tank 42 via piping 43. The sump tank 42 is originally vented by means of tubing 46 which extends to a two-position valve 94 at the surface equipment which leads in one position thereof to the atmosphere. The sub-sea sump tank 42 is connected to the surface sump tank via conduit 52. The surface sump tank contains a float operated pneumatic valve 93 which operates the two-position diaphragm controlled valve 94 to change from the previously mentioned vent position to a position connecting the air compressor 95 to the sub-sea sump tank 42 via conduit 46. The two-position valve 94 is returned to its vent position when the fioat 92 of float operated switching means 93 reaches a predetermined height in said surface sump tank causing the pressure applied to valve 94 by valve 93 to be relieved.

The sump tank 51 is connected via conduit 53 to a pump 54 which in turn is connected to storage chamber 62 via conduit 63. A 2500 p.s.i. pressure is maintained in storage chamber 62 by pump 54 which is controlled by pump control switch 64 which turns on pump motor 65 thereby causing pump 54 to pump the fluid from sump tank 51 to the storage chamber until the pressure is of a sufiicient value to shut off the pump control switch 64.

The storage chamber 62 is connected to the sub-sea storage vessel 21 via conduit 72, valve 73 and a check valve 74. The normal flow of fluid is from line 72 to vessel 21 through the check valve 74. The check valve has a needle valve 75 in parallel therewith. In the event that line 72 should break, the check valve would prevent rapid lo s of pressure from storage vessel 21, thereby roviding time in which the blowout preventers can be operated before the pressure is lost through needle valve 75. The needle valve 75 is provided so that the pressure of pressure storage vessel 21 can be read by gauge 96 at the surface. The opening of the needle valve 75 can be very small since there is essentially no flow of fluid during normal operation of the gauge. It can be seen that this arrangement matintains the sub-sea storage vessel 21 at the required 2500 p.s.i. pressure needed to provide operation of the blowout preventers. The transferral of the fluid from surface storage chamber 62 to the sub-sea storage vessel 21 is initiated by positioning valve 73 to the recharge position. When the pressure gauge 96 indictates the desired pressure has been attained in the subsea storage vessel, the recharge valve 73 can be returned to its operate position. A second output of the storage chamber 62 is shown connected to surge chamber 41 via conduit 77. A pressure reducing valve 78 is provided in the conduit 77 between the storage chamber 62 and the surge chamber 41 to maintain a constant pressure in the surge chamber.

As previously mentioned, FIG. 2 shows a cross-section of a two-position four-way control valve such as might be used for any of the valves 23, 24, 27 and 28. As can be seen, the control valve has two separate paths 8'1 and 82 therethrough which are capable of passing fluid in either direction. It can be seen that a rotation of the valve spool will make the connections shown in dotted line form, thereby providing completely diflferent paths 83 and 84 for the fluid flow. For example, considering valve 23, the fluid under pressure from storage vessel 21 will flow through the valve as shown so as to close the blowout preventer 12 whereas the return fluid from the blowout preventer passes through the valve and through piping 43 to sump tank 42. A 90 change of the valve spool will connect the fluid from pipe 22 to the open conduit going to the blowout preventer thus opening blowout preventer 12 whereas the displaced fluid will pass through the conduit 25 marked close, through the valve 23 to the sump tank 42 via piping 43. It will be appreciated that other control valve arrangements could be used to perform the same function. For example, a single pilot two-position valve with spring return would require only one control line per valve wherein the pressure in the control line would position the valve to hold the blowout preventer open and loss of pressure would allow the valve to close thus providing a fail-safe control in the event that the control tubing should break.

Referring to FIG. 3 there is shown schematically the position of the sub-surface storage vessel 21 and the sump tank 42 with respect to the blowout preventers 12 and 13. The well head, designated generally as 86, is shown seated on the water bottom 87. Sub-surface storage vessel 21 and sump tank 42 are shown mounted directly on the well head base 91. It will be appreciated that short lengths of piping such as piping 22 and 43 connect the storage vessel 21 and the sump tank 42 to the control valve respectively. It will be appreciated that there is no limitation on the diameter of the pipe 22 and 43 because of the high operating pressures used since they do not have to be flexible and can, therefore, be made of suitable strong metal. The relatively large diameter of the pipes and their short lengths will allow an extremely fast response of the blowout preventers when the control valves 23 and 24 are set fOr operation thereof since high pressures and large volume of flow can be obtained.

FIG. 4 shows a plan view of the apparatus of FIG. 3

and more particularly, shows the relationship of the control valves 23 and 24 to the blowout preventers 12 and 13. The corresponding parts in FIG. 3 and FIG. 4 are designated by similar reference numerals.

The detailed operation of the blowout preventer control system starting with the blowout preventers in the openposition will now be described. To close the blowout preventers, the operator at the remote surface location would set the valves 27 and 28 into the position shown schematically in FIG. 1. This would allow the fluid from surge chamber 41, which is under 150 p.s.i. pressure, to flow through both valves 27 and 28, through control tubing 32 and 34, to valves 23 and 24, respectively. The fluid under pressure in control tubing 32 and 34 would cause the hydraulic pistons of valves 23 and 24 to position the valves as shown in FIG. 1. Accordingly, the pressure from storage vessel 21 which is under 2500 p.s.i. pressure passes through the control valves 23 and 24 from piping 22 to the blowout preventers via pipes 25 and 26, each of which is marked close. The blowout preventers will, accordingly, close and the fluid displaced by the closing thereof will flow through pipes 19 and 20, the valves 23 and 24 as shown in FIG. 1, and thru piping 43 to sump tank 42. It will be appreciated that the blowout preventers can be operated simultaneously by one surface control switch or individually as shown in FIG. 1. The control system should now be reset for any further operation of the blowout preventers. This is accomplished by operating recharge valve 73 so as to connect the surface storage chamber 62 which is maintained at 2.500 p.s.i. pressure to the sub-surface storage vessel 21. This will cause the pressure in storage vessel 21 to again build up to the 2500 p.s.i. pressure which is in the area necessary for operation of the blowout preventers. As the pressure in surface storage chamber 62 drops below the 2500 p.s.i. pressure, the pump control switch automatically engages and starts the motor 65 of pump 54 which pumps fluid from the surface sump tank 51 via conduit 53 into storage chamber 62 until the pressure is again brought up to the required 2500 p.s.i. It can be seen that a recycling of the fluid from the sub-sea sump tank 42 to the surface sump tank 51 is necessary. This is accomplished automatically by the float controlled pneumatic valve 93 in the surface sump tank 51 which in turn operates two-position valve 94 to disconnect the sub-sea sump tank from vent and connect it to the air compressor 95. The air from the compressor 95 increases the pressure in the sump tank 42 thereby causing the excess fluid accumulated therein as a result of the operation of the blowout preventer to flow to the surface sump tank via conduit 52. As the fluid fills the surface sump tank 51, the float 92 will reach a position at which the float controlled valve 93 will shut-off and, accordingly, two-position valve 94 will again be operated and the sub-surface sump tank 42 is again vented to the asmosphere. Thus, the entire system is now in its initial condition and ready for any subsequent operation of the blowout preventers. At this time, the. recharge valve should be placed in the operate position. The pressure gauge 96 as previously mentioned indicates the pressure in the sub-sea storage vessel 21.

It can be seen that all of the electrical equipment of the hydraulic control system is located at the control station above the sea level and that all the necessary operating controls are also available for operation and servicing. It can also be seen that the particular control system provides fast and positive operation of the blowout preventers since the flow of fluid under pressure to the preventers is not limited by long lengths of small diameter conduits. Also, the system is a closed system thus preventing contamination of the fluid utilized in the system. This is important since the system must be protected from corrosion and sticking to provide reliability especially since the system in practice is operated at infrequent intervals but with maximum importance on positive operation when needed, that is, whenever the well threatens to blow out.

Obviously, many modifications and variations of the invention, as herein-before set forth, may be made without departing from the spirit and scope thereof, and therefore only such limitations should be imposed as are indicated in the appended claims.

I claim:

1. A control system for operating well shut-off apparatus located at a sub-sea well head, comprising a pressurized sub-sea fluid storage vessel located adjacent said subsea well head, a short length of large diameter pipe connecting said pressurized sub-sea fluid storage vessel to said well shut-off apparatus for passing large volumes of fluid under pressure in a short time to operate said well shutoff apparatus, a sub-sea fluid sump vessel located adjacent said well head, a short length of large diameter pipe connecting said sub-sea fluid sump vessel to said well shut-off apparatus for passing the large volume of fluid in a short time which is displaced by an operation of said shut-ofl? apparatus, a sub-sea two position four-way valve connected to both said pressurized sub-sea fluid storage vessel pipe for selectively applying said fluid under pressure to open and close said well shut-off apparatus and to said sub-sea fluid sump vessel pipe for correspondingly selectively applying the fluid displaced by said opening and closing of said well shut-0E apparatus to said sub-sea fluid sump vessel, a surface located fluid pressure source, a surface located two-way four-position valve for connecting said surface fluid pressure source to said sub-sea two-postion four-way valve to provide remote control operation thereof, surface located recharging means for recharging both said pressurized sub surface fluid storage vessel after operation of said well shut-01f apparatus and said surface fluid pressure source, a surface located sump means joined to said recharging means for supplying fluid thereto, and recycling means for transferring the fluid accumulated in said subsea sump vessel as a result of an operation of said well shut-off apparatus to said surface located sump means thereby conditioning said system for a further operation of said well shut-off apparatus.

2. A control system for operating apparatus located under water, comprising fluid pressure means located under water adjacent said apparatus and connected thereto for providing fast positive operation of said apparatus, sump means connected to and located adjacent said underwater apparatus for accumulating the fluid displaced by operation of said underwater apparatus, underwater valve means for switching the path of the pressurized fluid to operate said underwater apparatus either of two ways, means for controlling said underwater valve means from the surface of said water, means for recycling said fluid accumulated in said underwater sump means and means for recharging said underwater pressure means after an operation thereby conditioning said system for a further operation of said underwater apparatus, said recharging means comprising a pressurized surface located storage vessel and an automatically controlled pump to maintain said storage chamber at a predetermined pressure.

3. A control system for operating apparatus located under water, comprising fluid pressure means located under water adjacent said apparatus and connected thereto for providing fast positive operation of said apparatus, sump means connected to and located adjacent said underwater apparatus for accumulating the fluid displaced by operation of said underwater apparatus, underwater valve means for switching the path of the pressurized fluid to operate said underwater apparatus either of two ways, means for controlling said underwater valve means from the surface of said water, means for recycling said fluid accumulated in said underwater sump means and means for recharging said underwater pressure means after an operation thereby conditioning said system for a further operation of said underwater apparatus, said recycling means including a surface located sump means which includes a fluid level responsive valve controlled by the fluid level in said surface located sump means, a two-position valve operated in response to said fluid level responsive valve and a pneumatic pressure source, said two-position valve in one position connecting said underwater fluid sump means to the atmosphere and in the other position connecting the pneumatic pressure source to said underwater fluid sump means to provide pressure for transferring the excess fluid in said underwater fluid sump means to said surface sump means.

References Cited UNITED STATES PATENTS Kofahl 175-8 X Bauer et a1. 166'-.6 Haeber et a1. 166.6 Rhodes et al 175-7 Hoch 166.6 Lewis 166.6 Shatto et a1 166--.5

CHARLES E. OCONNELL, Primary Examiner.

R. E. FAVREAU, Assistant Examiner.

Claims

1. A CONTROL SYSTEM FOR OPERATING WELL SHUT-OFF APPARATUS LOCATED AT A SUB-SEA WELL HEAD, COMPRISING A PRESSURIZED SUB-SEA FLUID STORAGE VESSEL LOCATED ADJACENT SAID SUBSEA WELL HEAD, A SHORT LENGTH OF LARGE DIAMETER PIPE CONNECTING SAID PRESSURIZED SUB-SEA FLUID STORAGE VESSEL TO FLUID WELL SHUT-OFF APPARATUS FOR PASSING LARGE VOLUMES OF FLUID UNDER PRESSURE IN A SHORT TIME TO OPERATE SAID WELL SHUTOFF APPARATUS, A SUB-SEA FLUID SUMP VESSEL LOCATED ADJACENT SAID WELL HEAD, A SHORT LENGTH OF LARGE DIAMETER PIPE CONNECTING SAID SUB-SEA FLUID SUMP VESSEL TO SAID WELL SHUT-OFF APPARATUS FOR PASSING THE LARGE VOLUME OF FLUID IN A SHORT TIME WHICH IS DISPLACED BY AN OPERATION OF SAID SHUT-OFF APPARATUS, A SUB-SEA TWO POSITION FOUR-WAY VALVE CONNECTED TO BOTH SAID PRESSURIZED SUB-SEA FLUID STORAGE VESSEL PIPE FOR SELECTIVELY APPLYING SAID FLUID UNDER PRESSURE TO OPEN AND CLOSE SAID WELL SHUT-OFF APPARATUS AND TO SAID SUB-SEA FLUID SUMP VESSEL PIPE FOR CORRESPONDINGLY SELECTIVELY APPLYING THE FLUID DISPLACED BY SAID OPENING AND CLOSING OF SAID WELL SHUT-OFF APPARATUS TO SAID SUB-SEA FLUID SUMP VESSEL, A SURFACE LOCATED FLUID PRESSURE SOURCE, A SURFACE LOCATED TWO-WAY FOUR-POSITION VALVE FOR CONNECTING SAID SURFACE FLUID PRESSURE SOURCE TO SAID SUB-SEA TWO-POSITION FOUR-WAY VALVE TO PROVIDE REMOTE CONTROL OPERATION THEREOF, SURFACE LOCATED RECHARGING MEANS FOR