Subsea energy storage for blow out preventers (BOP)
11060372 ยท 2021-07-13
Assignee
- 1169997 Ontario Ltd. Operating as Aspin Kemp & Associates (Ontario, CA)
- TRANSOCEAN SEDCO FOREX VENTURES LIMITED (Grand Cayman, KY)
Inventors
Cpc classification
E21B33/0355
FIXED CONSTRUCTIONS
International classification
E21B33/035
FIXED CONSTRUCTIONS
E21B41/00
FIXED CONSTRUCTIONS
Abstract
A subsea energy storage for well control equipment, wherein stored energy near a well on the sea floor monitors and activates well control equipment independently of, or in conjunction with, hydraulic energy. Energy to the subsea energy storage can be supplied by surface umbilical, remotely-operated vehicle, or by subsea electrical generation from stored hydraulic energy. Stored electrical energy may also recharge stored hydraulic energy. A subsea control system is configured to record data, compare the data to predetermined event signatures, and operate the well control equipment with stored electrical energy.
Claims
1. A method, comprising: storing electrical energy near a well on a sea floor in an energy storage device, wherein the energy storage device is configured to provide stored electrical energy to operate well control equipment, and wherein the step of storing electrical energy includes: receiving a trickle charge of a current level below a first threshold from an umbilical connection to a surface power source during a first time period; receiving additional power of a current level above a second threshold from the umbilical connection to the surface power source during a second time period; storing hydraulic energy near the well on the sea floor in a hydraulic energy storage tank, wherein the hydraulic energy storage tank is configured to provide stored hydraulic energy to operate the well control equipment; operating a pump from the stored electrical energy to generate the stored hydraulic energy; and activating the well control equipment with a combination of the stored electrical energy, the received additional power, and the stored hydraulic energy, wherein the step of activating includes: activating the well control equipment for a first duration of time with the stored electrical energy and activating the well control equipment for a second duration of time with the stored hydraulic energy.
2. The method of claim 1, wherein the first time period is a time period comprising low-power sensing operations.
3. The method of claim 1, wherein the additional power comprises direct current (DC) power.
4. The method of claim 1, wherein the step of activating the well control equipment comprises activating a shear ram, and wherein activating the shear ram includes: activating the shear ram with the stored electrical energy to move the shear ram a first distance; and activating the shear ram with the stored hydraulic energy to move the shear ram a second distance.
5. The method of claim 2, further comprising, during the first time period: receiving data from a sensor near the well; and activating the well control equipment based on the data received from the sensor.
6. The method of claim 5, wherein the sensor is operated from the stored electrical energy.
7. The method of claim 5, further comprising: recording data from the sensor for a period of time; comparing the recorded data to at least one of a predetermined event signature and a historical event signature; and determining an event has occurred involving the well control equipment based, at least in part, on the step of comparing.
8. The method of claim 1, further comprising power conditioning the trickle charge received from the umbilical connection at the sea floor for storage in the energy storage device.
9. An apparatus, comprising: well control equipment; a subsea electrical power supply coupled to the well control equipment and configured to provide stored electrical energy to operate the well control equipment; a connector to receive an umbilical cable that is coupled to a surface power supply; a hydraulic reservoir configured to provide stored hydraulic energy; a hydraulic line coupled to the hydraulic reservoir and coupled to the well control equipment, the hydraulic line configured to supply the well control equipment with the stored hydraulic energy; and a control system configured to: receive a trickle charge of a current level below a first threshold from the umbilical cable during a first time period to provide the subsea electrical power supply with electrical energy; receive additional power of a current level above a second threshold from the umbilical cable during a second time period; and operate the well control equipment with a combination of the stored electrical energy, the received additional power, and the stored hydraulic energy, wherein the control system is further configured to: operate the well control equipment for a first duration of time with the stored electrical energy, and operate the well control equipment for a second duration of time with the stored hydraulic energy.
10. The apparatus of claim 9, wherein the first time period is a time period comprising low-power sensing operations.
11. The apparatus of claim 9, wherein the additional power comprises direct current (DC) power.
12. The apparatus of claim 9, wherein the control system is configured to operate a shear ram, and wherein the control system is configured to operate the shear ram by performing steps comprising: operating the subsea electrical power supply to move the shear ram a first distance using the stored electrical energy; and operating a hydraulic actuator to move the shear ram a second distance using the stored hydraulic energy.
13. The apparatus of claim 10, further comprising a sensor coupled to the control system, in which the control system is configured to receive data from the sensor during the first time period and configured to activate the well control equipment based, at least in part, on the data received from the sensor.
14. The apparatus of claim 13, wherein the sensor is configured to operate from the stored electrical energy.
15. The apparatus of claim 13, in which the control system is further configured to: record data from the sensor for a period of time to obtain recorded data; compare the recorded data to at least one of a predetermined event signature and a historical event signature; and determine an event involving the well control equipment has occurred based, at least in part, on the step of comparing.
16. The apparatus of claim 9, further comprising power conditioning circuitry configured to condition the received trickle charge for storage in the subsea electrical power supply.
Description
BRIEF SUMMARY OF THE DRAWINGS
(1) For a more complete understanding of the disclosed system and methods, reference is now made to the following descriptions taken in conjunction with the accompanying drawings.
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DETAILED DESCRIPTION
(8) In one embodiment, a blowout preventer (BOP) system may include a closed-loop hybrid electric/hydraulic system. Subsea energy storage is provided, allowing as-needed delivery of electrical power, such as through a low voltage, high current signal, to well bore electric components.
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(10) In conventional shear ram systems, valves to existing subsea, pressurized hydraulic fluid tanks are used to manipulate the cylinders through both low-power and high-power regions. As a hydraulic accumulator tank moves hydraulic fluid into the close line the pressure falls rapidly. In conventional ram systems, the highest pressure zone of the hydraulic tanks is wasted on moving the cylinders through the low-power region, where the cylinders are simply moved into place to contact the obstruction to be cut.
(11) The present embodiment provides increased efficiency by using hydraulic pump 206 to move hydraulic cylinders of ram 208 through the low-power region. When the cylinders contact an obstruction to be cut, pressurized hydraulic fluid tank valve 214A may be opened allowing high-pressure hydraulic fluid from tank 214 into the closed hydraulic line 230. The high-energy hydraulic fluid may assist in closing the cylinders of ram 208 to shear an obstruction in the well bore 220. In this way, the high-energy fluid is utilized for cutting, rather than just moving the cylinder through the low power region. Although a hybrid electrical/hydraulic system is described, the system may also use the hydraulic pump 206 to operate the cylinders of ram 208 through both the low-power phase and high-power phase.
(12) The use of electrical components, such as the pump 206, in the subsea system may allow redundancy to be increased. For example, the pressurized hydraulic fluid within tank 214 may be used to move the cylinders of ram 208 through the low-power region. Likewise, pump 206 may drive the cylinders of ram 208 through the high-power region. In one embodiment, sea water may be used in place of hydraulic fluid, such as in emergency situations when hydraulic fluid is unavailable. Hydraulic fluid may later be flushed through the subsea system to remove contaminants left by the sea water.
(13) The closed-loop design of the embodiment shown in
(14) A subsea electrical/hydraulic design may also provide other functionality. With the availability of the subsea stored electrical subsystem a BOP may perform local processing of data.
(15) The control board 310 may include memory and a processor. The processor may be configured to perform functions, such as collection of data from sensors 312 and control of motor 330 and/or valve 340 and other functions described in this disclosure. In one example, the control board 310 may be configured to activate the shear ram with stored electrical energy to move the shear ram a first distance and activate the shear ram with stored hydraulic energy to move the shear ram a second distance.
(16) Control board 310 may receive power from power supply 304 and information processed by communication block 308, which may be received from communications connection 360. The communications connection 360 may be a wireless connection without galvanic electric connections, which removes traditional electrical connectors and the water tight seals used to insulate the electrical connects from sea water. Communication transmissions may enter and leave the valve and sensor pack 202 via connection 360. In addition, communication block 308 may incorporate wireless technology for communicating with the sensors 312. Embedded sensors 312 may report status information to control board 310. One or more sensors may provide humidity, temperature, pressure, vibration, acceleration, flow, torque, position, power, or other information particular to a given valve, motor, or actuator. Control board 310 telemeters the raw measurements of sensors 312 for reporting purposes to the surface or to other subsea components. In addition, control board 310 may perform calculations, converting raw measurement data into interpretable telemetry, and/or other processing. For example, control board 310 may apply user-programmable calibrations to sensors 312. Because power may be stored and supplied in the subsea environment, system 300 may receive closed-loop feedback on any mechanical device. Moreover, control board 310 may include memory to allow recording of electrical signatures of one or more remote devices. Control board 310 may then interpret status information from the remote devices by comparing the electrical signatures with predetermined electrical signatures or historical signatures for the remote devices. For example, the control board 310 may be pre-programmed with an electronic signature for a shear ram failure that includes approximate measurements over time from a shear ram that may indicate a failure of the shear ram. The recorded electronic signature for the shear ram may then be compared with this pre-programmed electronic signature to determine if a failure has occurred or if service is required.
(17) Communications between control board 310, actuators, motors, valves, rams, indicators, and sensors may be by wired connection. In certain embodiments, wireless communication between components may be implemented, such as through radio frequency (RF) communications.
(18) Control board 310 may do more than just communicate with and interpret information from sensors 312. The connection to power module 306 may allow control board 310 to actively manipulate motor/actuator 330 as well as valve 340. Control board 310 may include dynamic memory, allowing aggregation of sensor data over time with time-stamps. According to one embodiment, control board 310 may record data over a set period of time to determine normal or even abnormal operating parameters and then, using on-board comparison algorithms, compare current data parameters to these historical parameters. In this way, control board 310 can determine whether an event has occurred. Moreover, the memory of control board 310 allows data logging to not be restricted by bandwidth limitations or line noise in the communications line 360. Thus, higher resolution data capture is possible. Operators may then download particular time-stamped event logs as desired through the communications line 360. Control board 310 may send detailed information about the valve's health and status, such as how fast the valve closed, how much energy was used to close the valve, the temperature increase during valve closure, high vibration or acceleration, etc. Moreover, control board 310 may compare the valve closure to previous closures to determine the health of the valve.
(19) According to one embodiment, control board 310 autonomously manipulates well equipment according to preprogrammed conditions. Thus, even if communication is cut off to the surface, subsea control board 310 possesses the power and the processor capability to independent operate the BOP. Control board 310 may also facilitate day-to-day operational corrections without the need for human intervention.
(20) According to another embodiment, control board 310 may process mathematical models of normal or abnormal operation of various components of well bore equipment. For example, given standard hydraulic start pressure, head-loss algorithms, depth of equipment, shear strength of an obstruction to be cut, etc., mathematical modeling will be able to calculate or estimate the amount of hydraulic fluid exiting a given accumulator. If that number differs by a certain amount, control board 310 may issue an event code that would alert operators on the surface. In addition, control board 310 may take autonomous action based on the event code. Over time, aggregated data and mathematical modeling provides operators additional information regarding the operation of a particular BOP. Operators may then update control board 310 autonomous response parameters according to predicted signatures.
(21) Subsea processing of data may allow for quicker control of equipment. For example, existing hydraulics may measure flow in limited places due to topside communication limitations discussed above. As a result, existing subsea hydraulic systems are prevented from simultaneously opening two valves upstream of a single flow meter because the operator would lose information regarding the flow through each individual valve. With the use of electrical system control, however, each valve could maintain its own powered valve and sensor pack complete with on-board sensors to measure flow, temperature, vibration, pressure, etc. Thus, more sensors and more actuators may be operated independently. Also, electrical control systems allow operators to make more adjustments and make adjustments more rapidly. As such, this feature may reduce time to emergency disconnect due to vessel problems.
(22) In deep sea, high-pressure environments, visual valve status may be limited by the availability of power and access to systems for processing data. According to one embodiment, an indication of the status of the valve may be available. Indication block 314 of
(23) According to one embodiment, the closed-loop electrical control system described herein may be modular in design, forgoing the use of a central topside processor and infrastructure. In this example, multiple components of well equipment may contain identical valve and sensor packs, as described in
(24) System 400, as depicted in
(25) Subsea power storage may allow each subsea actuator/sensor pack to be independent of any complex power source. Power distribution is low voltage and can be on the same conductors that are used for communication. In embodiments with DC power distribution, alternating electric and magnetic fields through the conductors is reduced, which removes a source of noise from the communications lines. The storage of power in a subsea system, such as the lower main riser package (LMRP), removes high peak currents from the umbilical cable circuit. Further, in certain embodiments, the subsea systems may operate with momentary or continuous loss of power from the surface. In embodiments with trickle charge capability, the management of voltage may be simpler and reduce the use for complex transformers at the subsea equipment. Further, surface-level Uninterrupted Power Systems (UPS) may be provided to supply DC power over the umbilical for additional redundancy. DC power on the surface-to-subsea umbilical lines also eliminates complex impedance issues and greatly simplifies the design of the cable. Because lower peak currents allow for smaller cable, more cable may be stored on the surface vessel. Lower gauge cable is also easier and faster to terminate, resists kinking, and simplifies repairs. Lower gauge cable is also faster and less expensive to replace, and can be terminated with existing ROV technology.
(26) Electronics package 404 may regulate power through system 400. In the embodiment shown in
(27) Electronics package 404 monitors and maintains an appropriate charge for storage device 402. In the embodiment shown, electronics package 404 may contain electronics and sensors such as associated with
(28) Subsea-stored electrical energy may be used to drive motor 414, which in turn is coupled to hydraulic pump 416. Motor 414 and pump 416 may have multiple uses in the subsea system. For example, pump 416 may accept hydraulic recharge fluid from ROV 434 and pump the fluid into hydraulic reservoir 410. Hydraulic reservoir 410 may be an ambient pressure fluid bladder contained in protective housing 411. Pump 416 may also transfer hydraulic fluid from ambient-pressure reservoir 410 to high-pressure hydraulic energy storage tanks 430. Pump 416 may pressurize tanks 430, creating hydraulic energy storage for use in ram 470 or for use in charging battery 402. Pump 416 may also accept hydraulic fluid from the surface along umbilical 452 for use in resupplying hydraulic reservoir 410. Pump 416 may also accept hydraulic fluid from ROV 432. In addition, pump 416 may drive motor 414 to recharge storage device 402. In power generation mode, ROV 434 pushes hydraulic fluid through pump 416 to ambient pressure reservoir 410. Pump 416 turns motor 414, which generates electricity to charge storage device 402. In an alternate embodiment, hydraulic fluid may be discarded to the sea through external valve 420. Hydraulic fluid may also or alternately be sent through pump 416 from pressurized hydraulic energy storage tanks 430.
(29) System 400 provides additional uses for an ROV. As mentioned, ROV 432 and ROV 434 may replenish hydraulic fluid to system 400. ROV 434 may also recharge storage device 402 through pump 416 and generator 414. In addition, ROV 434 may communicate directly with electronics package 404 in the event of problems with umbilical 450. Likewise, ROV 434 may provide raw DC power to electronics package 404 for use in powering system 400 or for recharging storage device 402. ROV 434 connects through induction and RF coupling device 442 which is capable of transferring both power and communications without a copper to copper connection.
(30) System 400 may include a conventional hydraulic energy storage subsystem. Pressurized hydraulic accumulator tanks 430 may be coupled to hydraulic operated valve and pump unit 460. Unit 460 contains pump 462, valve 464, sensor and electronics pack 466, and indicator 468. According to conventional hydraulic ram operation, high pressure hydraulic fluid may be passed through regulator 476 to valve 464 where it is directed to open or close ram 470. Excess hydraulic fluid may be exhausted to the sea through port 469. In the embodiment of
(31) In certain other embodiments, the indicator 468 may be a wireless interface to allow reporting of valve data to a hand held device accessed by a technician while the BOP is accessible on a ship deck or in a storage yard. While certain components of the subsea system are located on deck or in the storage yard, they may be provided power and communications interfaces to allow receiving of sensor data and verifying of operational components before installation subsea. Additionally, close loop hydraulic circuits discussed elsewhere allow operation of the BOP on the ship deck of in the storage yard without top-side hardware and hydraulic fluid.
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(33) Topside electronics 512 may communicate with electronics package 530. Telemetry may be sent topside and operational commands may be conveyed to well equipment. Telemetry and executed commands may be logged on data logging equipment 516. Telemetry may be displayed on topside displays 514 and also sent to remote locations via a internetwork or intranetwork 510. Commands may also be relayed via network 510.
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(35) LMRP 630 may contain an independent hydraulic energy storage 654 or be connected to BOP 670 hydraulic energy storage 664 through, for example, multipath hydraulic stabs 660 for hydraulic power connections to rams and valves. Electric power and communications may be transferred between LMRP 630 and BOP 670 through communication and energy transfer ports 656 and 662. Ports 656 and 662 may be hardwire connected or wirelessly coupled through induction. BOP 670 may include multiple rams 470 surrounding well bore 454. In one embodiment, rams 470 may include independent hydraulic-operated valve and pump units 460. In other embodiments, hydraulic-operated valve and pump units 460 may be interconnected to control and monitor multiple rams 470.
(36) The systems and methods described herein are scalable, and may be applied to either existing or new well equipment. Although the present disclosure and its advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the disclosure as defined by the appended claims. Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods and steps described in the specification. As one of ordinary skill in the art will readily appreciate from the present invention, disclosure, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized according to the present disclosure. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps.