Patent Application
20120275274
Not applicable.
This invention is in the field of oil and gas production. Embodiments of this invention are directed to the monitoring and communication of measurements, such as pressures, from deep subsea equipment, such as blowout preventers and capping stacks installed at offshore oil and gas wells.
As known in the art, the penetration of high-pressure reservoirs and formations during the drilling of an oil and gas well can cause a sudden pressure increase (“kick”) in the wellbore itself. A significantly large pressure kick can result in a “blowout” of drill pipe, casing, drilling mud, and hydrocarbons from the wellbore.
Blowout preventers (“BOPs”) are commonly used in the drilling and completion of oil and gas wells to protect drilling and operational personnel, and the well site and its equipment, from the effects of a blowout. In a general sense, a blowout preventer is a remotely controlled valve or set of valves that can close off the wellbore in the event of an unanticipated increase in well pressure. Modern blowout preventers typically include several valves, or “rams”, arranged in a “stack” surrounding the drill string. The valves within a given stack typically differ from one another in their manner of operation, and in their pressure rating, thus providing varying degrees of well control, including sealing of the well annulus at various pressures. Many BOPs include a valve of a “blind shear ram” type, which can sever the drill string and seal the wellbore, serving as potential protection against a blowout. As known in the art, the individual valves in blowout preventers are hydraulically actuated in response to initiation by electrical signals; other techniques for activating the blowout preventer include an “Autoshear” approach in which the valves are activated automatically in the event of an unplanned LMRP disconnect, and a “deadman” automatic mode in which the valves are activated in the event that the control systems lose their communication, electrical power, and hydraulic functions. In addition, some blowout preventers can be actuated by remote operated vehicles (ROVs), should the internal electrical and hydraulic control systems become inoperable. Typically, some level of redundancy for the control systems in blowout preventers is provided.
To carry out monitoring and analysis, measurements are obtained from the blowout preventer during periodic testing, and also by monitoring certain parameters during drilling and well completion. In deep sub-sea environments, sensors for measuring downhole pressure and other parameters are conventionally deployed in the “Christmas tree” at the seafloor, and in the blowout preventer. In addition, during the drilling operation, measurements regarding the drilling operation can be acquired (measurement-while-drilling, or “MWD”) downhole, as can measurements regarding the surrounding formation into which the drilling is being performed (logging-while-drilling, or “LWD”). During production, sensors in the production tubing at the seafloor or below are often deployed to make electrical measurements from which corrosion monitoring can be carried out.
These and other measurements must be communicated in some manner to the surface, for analysis by the appropriate systems and personnel. Various conventional communication techniques utilize the drill pipe or production tubing as the communications medium. For example, wired drill pipe and production tubing is now commonplace, with signals transmitted from the seafloor or even downhole along wire or optical fibers running the length of the drill pipe or tubing to the surface. These wired or fiber optic communications approaches are available for communication of pressure measurements from the blowout preventer. Other telemetry approaches useful in the drilling context include mud pulse telemetry within the drill string, and electromagnetic telemetry (EM tools).
In each of these cases, however, communication of pressure measurements from the seafloor or below utilize an intact physical communications conduit between the subsurface sensors and surface vessels, in the offshore production context. Unfortunately, given the environment often encountered in offshore production, as well as the long distances between surface and seafloor in modern deep offshore production, the communication conduit can become corrupted, compromised, or discontinuous. For example, the wire or optical fibers in “wired” production tubing can corrode, break, or otherwise lose good transmission capability.
In some cases, the drill string or production tubing may itself become broken or cut, for example in the case of a blowout of the well and subsequent severing of the riser from the blowout preventer, thus severing the communications facility between the seafloor and the surface. In these events, the monitoring of pressures at the blowout preventer, or at a subsequently deployed capping stack placed over the blown-out well, becomes beneficial in managing the failed well. These pressure measurements may provide an indication of the ability of the blowout preventer or capping stack to control the well, and also indicate whether the well casing and rupture disks are intact and maintaining integrity. In addition, pressure measurements at production equipment, such as the choke and kill lines at the blowout preventer, allow monitoring of remediation efforts involved in shutting-in the well after the blowout preventer rams have been activated.
By way of further background, the use of remote operated vehicles (ROVs) is now commonplace in offshore drilling and production. Navigation of an undersea ROV requires knowledge of its position relative to the subsea installations. As known in the art, the dynamic positioning of ROVs can be accomplished by acoustic signaling between the ROV and multiple fixed transponders. The fixed transponders, for example computerized acoustic telemetry transponders (“Compatts”) such as those available from Sonardyne, Inc., include acoustic transceivers for communication with ROVs and surface vessels. According to one conventional positioning approach, the ROV issues an acoustic interrogation signal to a transponder (e.g., a Compatt) deployed at a known location, in response to which the transponder issues an acoustic signal. The response signal may be a simple tone at a frequency particular to the specific transponder, or may be a modulated wideband signal (such as a phase-shift keyed, or PSK, modulated signal) such as the wideband technology used by the Sonardyne Compatts. In one approach, for example as used by the Sonardyne Compatts, the modulated response signal from the transponder includes information indicating the location of the transponder as deployed. Based on the location information and the travel time of the response signal (e.g., the round-trip travel time of the interrogation signal plus the response) from multiple fixed-location transponders, the location of the ROV can be calculated using triangulation or trilateralization (in which the location information of the transponder is used in combination with the signal travel time).
By way of further background, modern transponders, such as the COMPATT5 and COMPATT6 acoustic transponders from Sonardyne, Inc., are capable of carrying out data telemetry. These transponders can be deployed with optional sensors, such as inclinometers, pressure sensors, and strain gauges, and include a modem function to acoustically communicate measurement data acquired from those sensors. By way of still further background, the COMPATT6 acoustic transponder can operate in a data logging mode, by way of which measurements from its end cap sensors obtained over time can be stored within the transponder.
Copending and commonly assigned application Attorney Docket No. 41000, entitled “Acoustic Telemetry of Subsea Measurements from an Offshore Well”, filed contemporaneously herewith and incorporated herein by reference, discloses a system and method of obtaining measurement data from sensors at subsea equipment, such as a blowout preventer and a capping stack, and acoustically communicating that measurement data from an acoustic transponder connected to the sensors to an ROV or transponder supported from a surface ship, for communication of that measurement data to a surface network. As is known in the industry, however, inclement surface conditions at sea and other factors can preclude the deployment of surface ships in the vicinity of the well, which breaks the communications links between the subsea sensors and the personnel monitoring and managing the well in the manner described in that copending application. But the need for relatively continuous and real-time measurements of conditions at the well may well continue, despite the inclement surface conditions.
Embodiments of this invention provide a communications system and method of operating the same by way of which pressure measurements and the like at subsea equipment can be acquired and stored subsea for later acquisition, in situations in which the normal communications facility has been severed, compromised, or otherwise corrupted.
Embodiments of this invention provide a system and method in which subsea measurements can be acquired and stored despite surface conditions preventing the deployment of surface vessels and remotely operated vehicles (ROVs).
Embodiments of this invention provide a system and method that is suitable for use in deep subsea environments.
Embodiments of this invention provide a system and method that can be readily and rapidly deployed into the blowout preventer after its activation and the resulting shearing of the drill string or production tubing, and in advance of approaching weather events such as hurricanes.
Embodiments of this invention provide a system and method that is compatible with various coupling mechanisms at subsea installations.
Embodiments of this invention provide a system and method suitable for use in connection with both blowout preventers and capping stacks.
Other objects and advantages of embodiments of this invention will be apparent to those of ordinary skill in the art having reference to the following specification together with its drawings.
This invention may be implemented into a sensor and acoustic transponder arrangement that can be installed at appropriate locations of a sealing element assembly, such as a blowout preventer or capping stack, after the severing or compromise of the riser and drill string, or production tubing, as the case may be. The sensor is installed by way of a flange, or hot stab, to be in fluid communication with the desired location of the well or subsea equipment, and in electrical communication with an acoustic transponder. One acoustic transponder is electrically connected to the sensor, and is capable of transmitting measurement data upon interrogation. A monitoring acoustic transponder is installed near the first transponder, for example in advance of a hurricane or other surface event that prevents deployment of remotely operated vehicles (ROVs) and the like. This monitoring acoustic transponder is operable to acoustically interrogate the transponder connected to the sensor, on a periodic basis, and to store the measurement data acoustically transmitted in response, within its own memory. Once it is again safe for ships to be in the area, the stored data are acoustically retrieved from the monitoring acoustic transmitter, for example in response to an acoustic interrogation signal issued from an ROV or an acoustic transponder suspended in the vicinity of the acoustic monitoring transponder. The retrieved measurement data are then communicated to surface personnel aboard ship or at an onshore data center.
According to another aspect of the invention, the monitoring transponder may be installed at a subsea location within acoustic range of one or more acoustic transponders coupled with sensors at the subsea equipment, and acquires and stores measurement data over the desired period of time (such as during a storm in the vicinity of the well). Retrieval of the stored data from the monitoring transponder is carried out by physically retrieving the monitoring transponder, for example by way of an ROV, at which time the stored measurement data are directly downloaded over a wired connection into the servers at the surface vessel. This approach eliminates the acoustic polling of the monitoring transponder by an ROV.
a through 5e are elevation, perspective, and schematic views of a sensor and transponder arrangement according to an embodiment of the invention.
a through 6e are elevation, perspective, and schematic views of a sensor and transponder arrangement according to another embodiment of the invention.
a is an elevation view illustrating an offshore well after a blowout event, and including an acoustic monitoring transponder according to embodiments of the invention.
b is a flow diagram illustrating the operation of deployment and data acquisition in the system of
c is a flow diagram illustrating the operation of recovering stored measurement data from the acoustic monitoring transponder in the system of
d is an elevation view illustrating recovery of stored measurement data from an acoustic monitoring transponder according to an alternative embodiment of the invention.
e is a flow diagram illustrating the operation of recovering stored measurement data from the acoustic monitoring transponder in the system of
This invention will be described in connection with certain embodiments, specifically as implemented in connection with a blowout preventer, and other subsea equipment such as a capping stack, associated with a deepwater offshore oil well, as it is contemplated that this invention is especially beneficial when implemented in such an application. However, it is contemplated that this invention will be beneficial if applied to other types of equipment in similar environments. Accordingly, it is to be understood that the following description is provided by way of example only, and is not intended to limit the true scope of this invention as claimed.
Modern offshore drilling operations are carried out by way of computer monitoring and control systems. In this regard, drilling control computer 22 is provided at drilling rig 16, to control various drilling functions, including the drilling operation itself and the circulation and control of the drilling mud. Blowout preventer control computer 24 is a computer system that controls the operation of blowout preventer 18. Each of computer resources 22, 24, receives various inputs from downhole sensors along the wellbore, including from sensors deployed within blowout preventer 18. While each of drilling control computer 22 and BOP control computer 24 are deployed at offshore platform 20, in this example, these computer systems are in communication with onshore servers and computing resources by way of radio or satellite communications.
As evident from this description,
An example of a blowout preventer 18 including its LMRP is shown in greater detail in
In this example, as shown in
Control pods 28B, 28Y are also shown schematically in
For purposes of the description of embodiments of this invention,
During well control operations, upon actuating the appropriate rams of blowout preventer 18, kill fluid is pumped through the drillstring into the wellbore, circulating back to wellhead 12 via the annulus, and out of the well through choke line 33C to the backpressure choke, which is controlled to reduce the fluid pressure to atmospheric. In those cases in which circulation through the drill string is not possible, drilling mud is pumped from the surface into kill line 33K (and also possibly via choke line 33C in redundant fashion); this approach is known in the art as “bullheading”. In the event in which riser 15 is severed from the top of blowout preventer 18, it is known to control the well by severing one or both of kill line 33K and choke line 33C from riser 15, and connect these lines 33K, 33C, via a jumper line, to a source of drilling mud at the surface, or to a downhole collection and disposal manifold, or to an alternative source or destination for the fluid. With this connection, heavy drilling mud can be routed through the jumpers into either or both of choke line 33K and kill line 33C into the well via blowout preventer 18, to regain control of the well.
In a situation such as that illustrated in
In the generalized arrangement of
According to embodiments of this invention, the measurements obtained by sensors 55 are communicated to the surface via ROV 50. As such, the output signal from each sensor 55 is electrically coupled to a corresponding acoustic transponder 60. In the example of
Underwater acoustic communications between ROV 50 and transponders 52 for purposes of ROV navigation can be tone-based, with each transponder 52 issuing a response signal at an assigned frequency with no modulation. However, underwater communication of actual measurement data necessitates a more complex protocol than a simple tone at a given frequency. In embodiments of this invention, each transponder 60 transmits an acoustic signal that is modulated with the measurement data from its sensor 55. In a subsea environment in which acoustic transceiver 51 at ROV 50 (including, as described below, each of multiple ROVs 50 in the vicinity) is acoustically receiving measurement data from each of multiple transponders 60 for each of multiple associated sensors 55, data-bearing communications from each transponder 60 must be communicated in a dedicated channel to avoid interference. According to embodiments of this invention, such communication of measurement data by transponders 60 to acoustic transceivers 51 at corresponding ROVs 50 can be accomplished via wideband acoustic transmission as now supported by modern acoustic transponders, such as the COMPATT 5 and COMPATT 6 transponders available from Sonardyne, Inc., for example. Also as described above, acoustic transceiver 51 at ROV 50 may be the same acoustic transducer that, in combination with its transceiver electronics, is used in the navigation of ROV 50. Alternatively, a dedicated acoustic transducer or transceiver electronics, or both, may be used, if desired.
According to embodiments of the invention following the Sonardyne approach, each transponder 60 is assigned a dedicated transponder address code, to be used in generating a response to an interrogation signal received at a particular interrogation frequency. In this wideband implementation, the interrogation signals may also be wideband signals, with ROVs 50 controlled from different surface vessels having different assigned interrogation address codes relative to one another; typically, the interrogation carrier frequency differs from the response carrier frequency.
The operation of this procedure begins with process 62, in which acoustic transceiver 51 at ROV 50 issues an acoustic interrogation signal to a selected one of transponders 60, to initiate acquisition of measurement data from its associated sensor 55. As mentioned above, in the wideband acoustic context, this interrogation signal may be a wideband signal at a preselected acoustic carrier frequency, encoded according to the address code associated with ROV 50, and possibly including an interrogation message addressed specifically to the selected one of transponders 60 from which a response is desired. In process 64, transponder 60 receives this interrogation signal, and recognizes it as such. In response to the received interrogation signal, transponder 60 acquires one or more quanta of measurement data from its sensor 55 for transmission to the acoustic transceiver 51. It is contemplated that the communication of measurement readings from sensor 55 to transponder 60 can be carried out in various ways. According to a simple approach, transponder 60 has an electrical input at which it continuously receives, directly from sensor 55, an analog signal representative of the measurement at the present time; in this case, acquisition process 66 is performed by transponder 60 simply by sampling the analog level at its sensor input. Alternatively, depending on the capability of transponder 60, acquisition process 66 may involve retrieving one or more previously sampled measurement readings (with or without some filtering applied) from its internal memory.
In any case, in process 68, transponder 60 transmits an acoustic response signal including the measurements acquired in process 66. According to the example described above, this transmitted response signal is in the form of a modulated acoustic carrier signal at a preselected carrier frequency, with the modulations including the measurement data encoded according to the transponder address code assigned to that particular transponder 60, distinguishing it from other transponders 60 in the vicinity. In process 70, that acoustic response signal is received by the acoustic transceiver 51 at ROV 50 that issued the interrogation signal in process 62; in process 72, the transceiver electronics at ROV 50 operate to recover the measurement data from the modulated response signal, and communicate that measurement data in the appropriate manner to ship 48 via umbilical 49. Typically, more than one transponder 60 is within range of ROV 50 in its current position, such that the interrogation and response sequence repeats in sequence. If a next transponder 60 to be interrogated is not currently within the acoustic range of ROV 50 (decision 73 is “no”), surface ship 48 then navigates ROV 50 to a position within acoustic range of that next transponder 60 in process 74, in order to interrogate and receive a measurement from its associated sensor 55. In either that case, or if that next transponder 60 to be interrogated is in range (decision 73 is “yes”), the data acquisition and storage process of
Alternatively, measurement data can be acquired from transponders 60 without the use of ROV 50. For example, a wideband acoustic transponder such as the COMPATT 6 transponder, serving as the acoustic communications device, may be suspended directly from ship 48 by way of an umbilical including the appropriate wired communications facility, as shown in 151 of
According to embodiments of this invention, the monitoring of important parameters such as pressure and temperature at a well following a blowout event can be obtained in a relatively frequent and real-time manner, despite loss of the normal communication medium between the well and the surface due to the blowout. Typically, the frequency of consecutive measurement data points will depend on the number of transponders 60 in the polling sequence carried out by ROV 50 (or transponder suspended from ship 48, as mentioned above). These pressure and temperature measurements assist in attaining and maintaining control of the well in this event. The communications capability provided by embodiments of this invention can meet this need.
However, transponders 60 may not generally be deployed with blowout preventer 18 at the time of drilling, due to reliability considerations, although the invention includes such use. In addition, sensors that are originally implemented in blowout preventer 18 may not survive a blowout event, or may not be in position to sense the pressures and temperatures that are of particular importance for a well control strategy that becomes necessary in a specific situation. Of course, capping stack 45 will certainly not be in place during drilling, and will only be implemented after the event. As such, post-blowout installation of sensors 55 and associated transponders 60 is contemplated to be necessary. Embodiments of this invention are directed to the construction and post-blowout installation of sensors 55 and transponders 60, as will now be described.
Referring now to
a is an elevation view of an example of capping stack 45, as connected to riser 15. In this example, capping stack 45 includes upper and lower blind shear rams 38a, 38b, respectively, and single test ram 39. In this example, flange 75 is present at test ram 39, and provides a location that is in fluid communication with the wellbore below test ram 39, and at which pressure, temperature, and other parameters that may be measured will be relevant to the control of the well following a blowout event. In an example of the implementation of this embodiment of the invention, one or more sensors 55 will be installed post-blowout at this flange 75, for acoustic communication of measurements to the surface in the manner described above in connection with
a also illustrates the location of instrumentation and control panel 76 (along the left-hand side of capping stack 45 in that view), that will be utilized in connection with this embodiment of the invention. For example, panel 76 may correspond to either the choke panel or kill panel at capping stack 45, by way of which an ROV 50 can open or close various valves at rams 38a, 38b to carry out the desired choke or kill operation.
c illustrates, in cross-section, sensor assembly 80 used in connection with this embodiment of the invention. Sensor assembly 80 includes pressure/temperature sensor 55PT. An example of pressure/temperature sensor 55PT useful in connection with this embodiment of the invention is a Cormon 11 kpsi dual-pressure and single-temperature transmitter, with a 4-20 mA output, available from Teledyne Cormon Limited. Sensor 55PT is installed into location 75 (
d illustrates the physical arrangement of the communications transmitter function associated with sensor 55PT. Electrical conduit 83 extends from battery can 84 mounted to panel 85, as shown in
e illustrates the electrical arrangement of sensor 55PT and its associated acoustic transponders 600, 60k. In the schematic of
Resistors 920, 921, in this example, are nominal 250 Ω resistors, for converting the sensor output current range of 4 to 20 mA to the acoustic transponder input voltage range of 1 to 5 volts, maximizing the resolution of the communicated results. As such, conduit 860 includes two wires connected across resistor 920 within battery can 84, communicating the voltage drop across resistor 920 to transponder 860; conduit 861 similarly includes two wires connected across resistor 921 in battery can 84, communicating the voltage drop across resistor 921 to transponder 60k. Transponders 600, 601 each include their own battery, and thus do not require power from battery can 84. Considering that transponders 600, 601 sense input voltage, these devices present very high input impedance to the sensor circuits.
Because absolute temperature and pressure readings from blowout preventer 18 or capping stack 45, as the case may be, are desirable in the attaining and maintaining of well control, it is of course important to precisely know the resistances of each of resistors 920, 921. It has been observed, in connection with this invention, that the specified precision of conventional precision resistors is not necessarily adequate for this purpose. According to this embodiment of the invention, post-installation calibration of these resistors can be carried out based on the calibration data of the sensors obtained at the time of manufacture. According to this approach, for the example of pressure sensor 550, independent knowledge of the ambient pressure can be obtained, for example by obtaining a measurement from ROV 50 or by calculation. A pressure measurement from sensor 550 is then obtained under those same ambient conditions, by way of interrogation by ROV 50 in the manner described above. The signal received from associated acoustic transponder 600 will correspond to the voltage across resistor 920 for that measurement. Using the manufacturer calibration data to estimate the current at the known ambient pressure, the communicated voltage communicated by transponder 600 can be divided by that estimated current to precisely determine the resistance value of resistor 920. Once that precise resistance value is determined, the measured voltages communicated by transponder 600 can be divided by that resistance value to obtain the output current from sensor 550, and thus an accurate measurement of pressure, upon scaling the measured output current within its full output current range (e.g., between 4 mA to 20 mA), which corresponds to the minimum and maximum pressures indicated by the calibration data at those full current range endpoints. It has been observed, in practice, that this calibration approach provides good accuracy in the measurements obtained from sensors 550, 551, and thus provides a way to calibrate these important measurements post-installation.
This embodiment of the invention thus enables installation and operation of the necessary equipment and resources after a blowout event to communicate relatively frequent and real-time measurements of important parameters, such as pressure, temperature, and the like, based upon which well control actions can be determined and evaluated.
According to another embodiment of the invention, as will now be described in connection with
a illustrates this arrangement in a generalized form. As shown in that Figure, kill line 33K of blowout preventer 18 has been severed from riser 15, and re-routed via jumper conduit 33J to a source of drilling mud at the surface, or to a downhole collection and disposal manifold, or to some other source or destination of the fluid conducted via jumper conduit 33J and kill line 33K, depending on the particular well control operation. In any case, parameters such as pressure and temperature at the interior of jumper conduit 33J are of interest to the well control operations. According to this embodiment of the invention, sensors 55PT are connected to be in fluid communication with jumper conduit 33J on one side, and in electrical connection with acoustic transponder 60. As described above, acoustic transponder 60 communicates acoustic signals encoded with data corresponding to the pressure or temperature measurements acquired by sensors 55PT, upon receipt of an interrogation signal from an acoustic communications device, such as acoustic transceiver 51 mounted on ROV 50 in combination with its transceiver electronics, as described above. In that example, acoustic transceiver 51 receives the encoded response signal from acoustic transponder 60, and its associated transceiver electronics then communicate data corresponding to the acquired measurements via umbilical 49 to computing and monitoring systems at ship 48.
b shows a hydraulic and electrical schematic of the sensor and communications system according to this embodiment of the invention. As will be apparent to those skilled in the art, the connection of kill line 33K or choke line 33C to some other source or destination in response to a blowout event requires the installation of the appropriate jumper conduit and other equipment, in connection with the well control procedure. According to this embodiment of the invention, a portion of the sensor and communications system is installed initially with this jumpering onshore, prior to deployment of the combination of jumper conduit 33J; sensors 55PT and acoustic transponder 60 are subsequently installed by way of an ROV at the appropriate time.
In this embodiment of the invention, system portion 100a is installed onto jumper conduit 33J prior to deployment. System portion 100a includes instrumentation tubing 102, which is in fluid communication with the vessel or tubing to be monitored, which in this case is jumper conduit 33J. Paddle valve 104 is in-line with instrumentation tubing, with dial gauge 106 optionally plumbed into instrumentation tubing 102 beyond paddle valve 104. Instrumentation tubing 102 terminates at hot stab receptacle 108, which is mounted to an appropriate gauge panel 125, which is shown in
Referring back to
c illustrates floatation attachment 130, to which housing 120 (and thus sensor 115 and its battery 114) is mounted. Floatation attachment 130 is a small panel to which housing 120 is mounted opposite lead cone 132; ROV handle 134 is mounted to the housing side of floatation attachment 130. Lead cone 132 facilitates mounting of floatation attachment 130 by an ROV in the subsea environment, by way of the insertion of lead cone 132 into opening 129 of panel 125.
d and 6e schematically illustrate the fluid and electrical connection among the various components of system portions 100a, 100b. As shown in
As shown in
The communication of measurements obtained by sensor 115 (within housing 120) according to this embodiment of the invention is similar to that described above for the flanged installation. Accordingly, upon insertion and mating of hot stab connector 110 into and with hot stab receptacle 108, the interior of housing 120 is in fluid communication with jumper conduit 33J, via hydraulic conduit 102, 112, and paddle valve 104. Sensor 115 is thus able to sense the particular parameter (e.g., pressure) of that fluid, and thus the fluid of jumper conduit 33J as desired. It is contemplated that this hot stab sensor installation will generally be better suited for sensing and communicating pressures rather than temperatures. Sensor 115 issues an electrical signal (e.g., a voltage within a specified range) to acoustic transponder 60 corresponding to the sensed pressure, temperature, or other parameter. Upon receipt of an acoustic interrogation signal from an acoustic communications device, such as acoustic transceiver 51 on ROV 50, as described above, acoustic transponder 60 transmits an acoustic signal encoded with data corresponding to the measurement obtained by sensor 115. In that example, acoustic transceiver 51 and its associated transceiver electronics at ROV 50 then communicate data corresponding to this and other measurements acquired from other sensors, to surface personnel via umbilical 49 and ship 48, in the manner described above.
According to this embodiment of the invention, post-blowout installation and operation of the necessary equipment and resources to monitor and frequently communicate real-time measurements of important parameters relevant to well control operations can be carried out.
In the event of blowout of an offshore oil and gas well, a large number of personnel may be involved in taking remedial action. Time may be of the essence in making decisions regarding well control actions to be taken, and the importance of those decisions requires evaluation of the best available subsea measurement data. Reliability in the acquisition and communication of those subsea measurement data at a relatively high frequency and continuously over time is therefore an important attribute of the overall measurement communication system.
As described in copending and commonly assigned application Attorney Docket No. 41000, entitled “Acoustic Telemetry of Subsea Measurements from an Offshore Well”, filed contemporaneously herewith and incorporated herein by reference, a high level of communications network redundancy can be implemented in connection with the acoustic telemetry of measurements at blowout preventer 18 and capping stack 45. This redundancy includes the use of multiple ROVs 50 in the vicinity of blowout preventer 18 and capping stack 45, each interrogating each acoustic transponder 60 and receiving measurement data in response. These multiple ROVs 50 are supported from multiple associated surface ships 48, each of which has its own computer network on board, by way of which measurement data acquired from subsea sensors at blowout preventer 18 and capping stack 45 can be monitored and analyzed as desired. In addition, according to the redundancy implemented in this embodiment of the invention, each ship 48 includes multiple communication facilities for communicating those data and local analysis. Those communications facilities include satellite communications capability and also wireless radio communications capability. For example, wireless radio communications may be used for communications within a “local” area network made up of the computer networks among ships 48 that are at sea and in the vicinity of the well. Satellite communications may be used in connection with that “local” area network as well and also for communication with one or more data centers located on shore, or around the world as the case may be.
In any event, according to embodiments of this invention, substantial redundancy is provided in the communications network involved in obtaining and integrating measurement data from subsea sensors at the well following a blowout event, without requiring the riser, drill string, or other physical conduit to be in place. As such, if an issue arises regarding any one of the radio or satellite communications links, multiple alternative data paths in the overall network are provided according to embodiments of this invention, whether among the ships at the well site, or among onshore facilities such as data centers, or both. This redundancy also does not rely on a single data acquisition and processing protocol, thus enabling multiple vendors to be involved at the well. The overall robustness of the system is therefore improved.
The communication of measurement data from sensors 55 and acoustic transponders 60 via ROVs 50 to surface personnel requires deployment of ROVs 50 and their supporting surface ships 48 in the vicinity of the well. As is well known in the industry, however, surface conditions at sea are not always conducive to the deployment of ships 48 and ROVs 50, especially in storm-vulnerable locations such as the Gulf of Mexico. In particular, tropical storms and hurricanes require evacuation of surface vessels from sea-going locations in the path of those storms. According to the systems described above, which rely on ROVs and the like to communicate measurement data from the seafloor to the surface, such evacuation breaks the communications links between the subsea sensors and the personnel monitoring and managing the well. Especially in events such as blowouts and the remediation of those blowouts, the need for relatively continuous and real-time measurements of conditions at the well continues, however.
According to embodiments of the invention, capability for acquiring measurement data from subsea equipment at the well, for example at blowout preventer 18 and capping stack 45 in the situation of
a illustrates a subsea situation similar to that described above in connection with
In the situation of
According to this embodiment of the invention, acoustic monitoring transponders 150 may be implemented by way of a conventional acoustic monitoring transponder 150 having data logging capability, and capable of wideband or other high data rate acoustic communications capability for transmitting and receiving acoustic signals encoded with measurement data. An example of such a modern transponder suitable for use in connection with this embodiment of the invention is the COMPATT6 acoustic transponder available from Sonardyne, Inc. Other transponders that include these capabilities may alternatively be used.
In addition to the placement or mounting of acoustic monitoring transponders 150, as described above, the manner and timing of the deployment of acoustic monitoring transponders 150 may vary. It is contemplated, for example, that acoustic monitoring transponders 150 will generally not be deployed at the same time as acoustic transponders 60 and sensors 55 as the case may be. According to this approach, acoustic monitoring transponders 150 would be deployed only if necessary in advance of an approaching tropical storm or hurricane; acoustic communications via ROV 50 as described above would be the usual technique for communicating measurement data to the surface. Alternatively, of course, acoustic monitoring transponders 150 may be deployed in conjunction with the deployment of measurement acoustic transponders 60. Further in the alternative, acoustic monitoring transponders 150 may themselves be the same transponders as used for ROV navigation (i.e., may serve also as transponders 52 in the situation of
According to embodiments of this invention, the measurements obtained by each sensor 55 are communicated to its corresponding acoustic transponder 60. Each transponder 60 receives an output electrical signal from its associated sensor 55, and upon receiving an acoustic interrogation signal, that transponder 60 transmits an acoustic signal encoded with data representative of the pressure, temperature, or other parameter sensed by sensor 55. In this embodiment of the invention, acoustic monitoring transponder 150, deployed in the vicinity of the well, issues the interrogation signal to transponders 60a through 60c, and stores measurement data encoded within the acoustic response signal transmitted by transponders 60a through 60c in response to that interrogation signal. Acoustic monitoring transponder 150 is operating in a “data logging” operational mode in this instance, and stores those measurement data in its internal memory resource. In this embodiment of the invention, it is contemplated that acoustic monitoring transponder 150 will be operating essentially in an autonomous fashion, periodically issuing acoustic interrogation signals to each of transponders 60a through 60c individually, and storing the measurement data in the corresponding response signals for later retrieval. ROV 50 is thus not involved in the acquisition and storing of measurement data at acoustic monitoring transponder 150, in this embodiment of the invention.
The view of
Referring now to
In process 162, one or more acoustic monitoring transponders 150 are deployed near the well. For clarity, this process of
Decision 163 determines whether conditions at the surface of the sea, overlying the well, remain safe for surface ships 48 and thus for the navigation of ROVs 50 supported by those ships 48. If so (decision 163 is “yes”), process 64 is performed to acquire and communicate measurement data from sensors 55 via transponders 60 and ROV 50, in the manner described above in connection with
The acquisition and monitoring operation begins with process 168, in which acoustic monitoring transponder 150 transmits an acoustic interrogation signal to one of its associated transponders 60. This interrogation signal can be identical, as far as transponder 60 is concerned, to that issued by acoustic transceiver 51 at ROV 50 in the data acquisition process described above in connection with
If multiple transponders 60 are to be interrogated by acoustic monitoring transponder 150, processes 168 through 176 will then be repeated by acoustic monitoring transponder 150 and the remaining transponders 60 to be interrogated within a given interval. Specifically, in decision 177, acoustic monitoring transponder 150 determines whether additional sensors within its range are to be interrogated within this interrogation period. If so (decision 177 is “yes”), then an index indicating the particular sensor 55 and transponder 60 to be interrogated is incremented, and control returns to process 168 to interrogate and retrieve measurement data from that sensor 55 via its transponder 60.
As mentioned above, the measurement data acquisition and storage performed by acoustic monitoring transponder 150 in this embodiment of the invention is contemplated to be carried out periodically, according to configuration information communicated to it in process 166, or stored within acoustic monitoring transponder 150 prior to deployment. If no more sensors 55 are to be interrogated in this monitoring period (decision 177 is “no”), decision 179 is executed to determine whether the monitoring period has yet elapsed. If not (decision 179 is “no”), acoustic monitoring transponder 150 continues to wait until that period has elapsed, at which time (decision 179 is “yes”), control returns to process 168 in which acoustic monitoring transponder 150 next interrogates the first transponder 60 in its sequence to acquire its next measurement value. The process continues for each deployed acoustic monitoring transponder 150, interrogating each of its associated transponders 60, in the absence of ROV 50 or other surface-supported vehicles.
c illustrates an example of the operation of this system in retrieving the stored measurement data from acoustic monitoring transponder 150. This data retrieval will typically be performed as soon as practicable after the storm conditions at the surface, or other situation precluding the deployment of surface ships 48 and ROVs 50, has cleared. In process 180 of
It is contemplated, in this embodiment of the invention, that ROV 50 will acquire and communicate measurement data from sensors 55 and transponders 60 under calm surface conditions. In this case, process 188 is then performed by the acoustic transceiver 151 at ROV 50 transmitting an acoustic control signal to acoustic monitoring transponder 150 to de-activate its monitoring (i.e., interrogation and acquisition) operation. Acoustic monitoring transponder 150 then may be retrieved, if desired, or may simply remain idle awaiting the next event causing it to be activated.
An alternative data recovery process is also shown in
Referring now to
The operation of the arrangement of
According to this embodiment of the invention, two options are provided for communicating the acquired measurement data to the surface network. In one approach (option 1 of
According to another option (option 2 of
In either option, the stored measurement data acquired over time by acoustic monitoring transponder 150 are retrieved without requiring deployment of an ROV or other underwater vehicle. These approaches can, in some instances, reduce the cost of acquiring the measurement data, by enabling the use of lower-cost transponders rather than navigable ROVs and the like.
According to this embodiment of the invention, therefore, measurement of critical pressures, temperatures, and other parameters at the seafloor can be acquired even if storm and other inclement surface conditions preclude the use of ROVs and surface support ships. The subsea measurement data can be acquired at relatively high frequency (e.g., on the order of every few minutes) and stored locally, near the seafloor, for later retrieval. The local acquisition and storage by acoustic monitoring transponders, according to this embodiment of the invention, is essentially transparent to the measurement acoustic transponders, minimizing the pre-storm emergency deployment actions and thus facilitating rapid response.
According to embodiments of this invention, sensors can be installed subsea, for example after an event such as blowout of a well, and their measurements obtained and communicated without the presence of a riser, drill string, or production tubing supporting the communications medium. In particular, sensors and corresponding acoustic transceivers are installed at locations of a blowout preventer, capping stack, or other sealing element assembly, with the acoustic transceivers capable of acoustically communicating the measurement data upon interrogation by a remotely-operated vehicle in the vicinity of the well. According to an embodiment of the invention, if ROV operation becomes imprudent due to storms and hurricanes in the well vicinity, acoustic monitoring transponders can be deployed to acquire and store the measurement data for later retrieval. Upon receipt of the measurement data at a surface vessel, a redundant communications network is implemented by way of which data may be communicated among the vessels in the vicinity, and by satellite to onshore data centers, for monitoring and analysis. The continuous and real-time measurements acquired and analyzed in this manner facilitate the rapid and effective selection and evaluation of well control actions.
It is contemplated that embodiments of this invention can be utilized in alternative applications. For example, it is contemplated that this invention can be readily applied, by those skilled in the art having reference to this specification, to subsea structures for which a communications medium is not already in place. For example, the sensors may correspond to corrosion detectors, implemented into subsea structures (e.g. subsea pipelines) and their measurements acoustically communicated to ROVs, in the manner described herein.
While the present invention has been described according to its embodiments, it is of course contemplated that modifications of, and alternatives to, these embodiments, such modifications and alternatives obtaining the advantages and benefits of this invention, will be apparent to those of ordinary skill in the art having reference to this specification and its drawings. It is contemplated that such modifications and alternatives are within the scope of this invention as subsequently claimed herein.
This application claims the benefit of U.S. Provisional Application No. 61/479,260 filed Apr. 26, 2011. This application is related to copending and commonly assigned Attorney Docket Number 41000 entitled “Acoustic Telemetry of Subsea Measurements from an Offshore Well”, filed contemporaneously herewith and incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 61479260 | Apr 2011 | US |
