Patent Application
20150027735
This disclosure relates generally to equipment utilized and operations performed in conjunction with a subterranean well and, in an example described below, more particularly provides for long term electrical power storage in downhole tools.
It is known to store electrical power downhole in batteries. The batteries may be used to operate electronic circuitry of a downhole tool. In order to conserve the electrical power while the electronic circuitry is not being actively used in operation of the tool, the electronic circuitry can be placed in “sleep” mode.
Unfortunately, the electronic circuitry continues to consume electrical power, even while in sleep mode. For example, the electronic circuitry may need to receive and process measurements made by a sensor, in order to detect when the electronic circuitry should “awaken” from the sleep mode. This electrical power consumption by the electronic circuitry in the sleep mode can significantly reduce the stored electrical power over long periods of time.
Therefore, for the above reasons and others, it will be appreciated that improvements are continually needed in the art of providing long term electrical power storage for downhole tools. Such improvements can be useful whether or not batteries are used for downhole electrical power storage, and whether or not any circuitry is awaken from a sleep mode, etc.
Representatively illustrated in
The tubular string 12 may be of the type known to those skilled in the art as casing, liner, tubing, a production string, a work string, a drill string, etc. Any type of tubular string may be used and remain within the scope of this disclosure.
The packers 18a-e seal off an annulus 20 formed radially between the tubular string 12 and the wellbore 14. The packers 18a-e in this example are designed for sealing engagement with an uncased or open hole wellbore 14, but if the wellbore is cased or lined, then cased hole-type packers may be used instead. Swellable, inflatable, expandable and other types of packers may be used, as appropriate for the well conditions, or no packers may be used (for example, the tubular string 12 could be expanded into contact with the wellbore 14, the tubular string could be cemented in the wellbore, etc.).
In the
The zones 22a-d may be sections of a same formation 22, or they may be sections of different formations. Each zone 22a-d may be associated with one or more of the injection valves 16a-e.
In the
It is sometimes beneficial to initiate fractures 26 at multiple locations in a zone (for example, in tight shale formations, etc.), in which cases the multiple injection valves can provide for injecting fluid 24 at multiple fracture initiation points along the wellbore 14. In the example depicted in
Preferably, the other valves 16a,b,d,e are closed while the fluid 24 is being flowed out of the valve 16c and into the zone 22b. This enables all of the fluid 24 flow to be directed toward forming the fractures 26, with enhanced control over the operation at that particular location.
However, in other examples, multiple valves 16a-e could be open while the fluid 24 is flowed into a zone of an earth formation 22. In the well system 10, for example, both of the valves 16b,c could be open while the fluid 24 is flowed into the zone 22b. This would enable fractures to be formed at multiple fracture initiation locations corresponding to the open valves.
It will, thus, be appreciated that it would be beneficial to be able to open different sets of one or more of the valves 16a-e at different times. For example, one set (such as valves 16b,c) could be opened at one time (such as, when it is desired to form fractures 26 into the zone 22b), and another set (such as valve 16a) could be opened at another time (such as, when it is desired to form fractures into the zone 22a).
One or more sets of the valves 16a-e could be open simultaneously. However, it is generally preferable for only one set of the valves 16a-e to be open at a time, so that the fluid 24 flow can be concentrated on a particular zone, and so flow into that zone can be individually controlled.
At this point, it should be noted that the well system 10 and method are described herein and depicted in the drawings as merely one example of a wide variety of possible systems and methods which can incorporate the principles of this disclosure. Therefore, it should be understood that those principles are not limited in any manner to the details of the system 10 or associated method, or to the details of any of the components thereof (for example, the tubular string 12, the wellbore 14, the valves 16a-e, the packers 18a-e, etc.).
It is not necessary for the wellbore 14 to be vertical as depicted in
In other examples, the principles of this disclosure could be applied in circumstances where fluid is not only injected, but is also (or only) produced from the formation 22. In these examples, the fluid 24 could be oil, gas, water, etc., produced from the formation 22. Thus, well tools other than injection valves can benefit from the principles described herein.
Referring additionally now to
In
In
Initially, the chamber 66 is at or near atmospheric pressure, and contains air or an inert gas. Thus, the support fluid 63 can readily flow into the chamber 66, allowing a sleeve 32 to displace downwardly, due to a pressure differential across a piston 52.
In
The magnetic sensor 40 is preferably separated from the flow passage 36 by a pressure barrier 82 having a relatively low magnetic permeability. The pressure barrier 82 may be integrally formed as part of the plug 80, or the pressure barrier could be a separate element, etc.
Suitable low magnetic permeability materials for the pressure barrier 82 can include Inconel and other high nickel and chromium content alloys, stainless steels (such as, 300 series stainless steels, duplex stainless steels, etc.). Inconel alloys have magnetic permeabilities of about 1×10−6, for example. Aluminum (magnetic permeability ˜1.26×10−6), plastics, composites (e.g., with carbon fiber, etc.) and other nonmagnetic materials may also be used.
One advantage of making the pressure barrier 82 out of a low magnetic permeability material is that the housing 30 can be made of a relatively low cost high magnetic permeability material (such as steel, having a magnetic permeability of about 9×10−4, for example), but magnetic fields produced by a magnetic device 38 (not shown in
In some examples, a relatively high magnetic permeability material 84 may be provided proximate the magnetic sensor 40 and/or pressure barrier 82, in order to focus the magnetic flux on the magnetic sensor. A permanent magnet (not shown) could also be used to bias the magnetic flux, for example, so that the magnetic flux is within a linear range of detection of the magnetic sensor 40.
In some examples, the relatively high magnetic permeability material 84 surrounding the sensor 40 can block or shield the sensor from other magnetic fields, such as, due to magnetism in the earth surrounding the wellbore 14. The material 84 allows only a focused window for magnetic fields to pass through, and only from a desired direction. This has the benefit of preventing other undesired magnetic fields from contributing to the sensor 40 output.
When the actuator 50 is actuated, the piercing member pierces the pressure barrier 48, thereby allowing the support fluid 63 to flow into the chamber 66, and allowing the sleeve 32 to displace downward due to a pressure differential across the piston 52. When the sleeve displaces downward, openings 28 in the housing are unblocked, thereby permitting fluid flow between the annulus 20 and the passage 36.
A locking device 54 (for example, a snap ring) can be used to prevent subsequent upward displacement of the sleeve 32. In other examples, it may be desired to close the valve 16 after it has been opened. In those examples, the locking device 54 may not be used, or it may be releasable.
Note that the valve 16 is depicted in the drawings and described herein as merely one example of a downhole tool that can embody principles of this disclosure. Other examples of valves that can embody the principles of this disclosure are described in U.S. patent application Ser. No. 13/440,823.
Packers 18a-e and other types of downhole tools can embody this disclosure's principles. Other downhole tools can be activated by permitting current flow between an electrical power source and an electrical load of any type. Therefore, the scope of this disclosure is not limited to the details of the valve 16, or to any particular type of downhole tool.
Referring additionally now to
The control system 34 as depicted in
At an appropriate time, the circuitry 42 delivers electrical power from an electrical power source 56, such as, batteries, a charged capacitor, etc., to actuate the actuator 50. In other examples, the circuitry 42 may permit electrical current flow between the power source 56 and another type of electrical load (such as, a data gathering device, a heater, etc.).
In the
Another (optional) sensor 58 can be used for determining whether the actuator 50 should be actuated. For example, the sensor 58 could sense pressure so that, unless the valve 16 is positioned downhole (e.g., exposed to a pressure of at least, say, 500 psi), the circuitry 42 will not cause the actuator 50 to actuate. Any number and/or type of sensors may be used for determining whether and when the actuator 50 should be actuated, in keeping with the principles of this disclosure.
However, in this example, the circuitry 42 is not continuously monitoring outputs of the sensors 40, 58, and is not in a “sleep” mode, during most of its presence downhole. Instead, a switch 60 is used to selectively permit current flow between the power source 56 and the circuitry 42, in response to generation of electricity downhole by a generator 62. In this manner, the control system 34 does not consume electrical power during most of its presence downhole and, thus, the electrical power is conserved.
The generator 62 is caused to generate electricity when it is desired for the circuitry 42 to begin monitoring the sensor 40 and/or sensor 58. For example, the switch 60 would be “off” as the tubular string 12 of
Referring additionally now to
The switch 60 is depicted in
When a conducting channel is formed between a source and drain of the transistor 68 (for example, by application of a voltage from the generator 62 to the gate of the transistor), a voltage drop is created between a gate and a source of the switch 60, thereby causing a conductive channel to be formed between the source and a drain of the switch. At this point, electrical current flow between the power source 56 and the control circuitry 42 is permitted.
Another transistor 70 maintains the voltage applied to the switch 60 gate, even though the generator 62 may discontinue generating electricity. If it is desired to turn the switch 60 “off” after it has been turned “on,” a reset circuit can readily be configured to selectively ground a gate of the transistor 70. This can permit testing of the switch circuit (and the control circuitry 42, sensors 40, 58, etc.) at surface, prior to installing the control system 34 in the wellbore 14.
It is not necessary for semiconductor devices as described above to be used in the switch circuit. In other examples, electromechanical devices, such as relays or latching relays, may be used.
As mentioned above, the generator 62 is depicted in
In the system 10 of
The thermoelectric generator 62 could be positioned so that it is exposed to the relatively hot environment on one side, and to the relatively cool fluid 24 on an opposite side. For example, the thermoelectric generator 62 could be positioned in a side wall of the valve 16, such as, in a wall of the housing 30 (see
A phase changing material, such as a fuseable alloy, or a heat sink (not shown) could be used to maintain a consistent or larger temperature difference over a longer period of time. For example, a heat sink can be used to increase the temperature differential and, thus, to increase the electrical power generated.
Referring additionally now to
A wire coil 72 can be positioned in the housing 30 encircling the passage 36 so that, as the magnetic device 38 displaces through the coil, a voltage is produced at a terminal 74 of the coil. The terminal 74 can be connected to the switch circuit of
It may be desirable for the sensor 40 (see
For example, after displacing the magnetic device 38 through the passage 36, one downhole tool could be actuated in response to displacing another corresponding magnetic device, and another downhole tool could be actuated in response to displacing yet another corresponding magnetic device, etc. The scope of this disclosure is not limited to any particular method of actuating downhole tools after the switch(es) 60 have been turned “on.”
It is not necessary for the actuator 50 to cause an overt physical actuation of the downhole tool 16. Instead, activation of the tool 16 in response to the generation of electricity by the generator 62 could be in the form of, for example, initiation of data recording (e.g., as in during a formation test, a completion or conformance evaluation, etc.). Thus, activation of the downhole tool 16 can comprise supplying electrical current to any type of electrical load, in keeping with the scope of this disclosure.
Referring additionally now to
A “power harvester” can be used for the device 86. One suitable power harvester for use as the device 86 is a VOLTURE™ energy harvester marketed by Mide Technology of Medford, Mass. USA. Other devices which can function to generate electricity from movement or vibration may also be used.
Thus, it will be appreciated that a variety of techniques can be used to generate electricity downhole, so that the switch 60 can be turned “on” when desired. Electricity can be generated in response to flow of the fluid 24 through the passage 36 (e.g., as in the
It may now be fully appreciated that the above disclosure provides significant benefits to the art of controlling activation of downhole tools. In examples described above, electrical energy can be stored downhole for extended periods of time, without being used by circuitry of downhole tools.
A method of activating a downhole tool 16 in a subterranean well is provided to the art by the above disclosure. In one example, the method can comprise: configuring the downhole tool 16 having an electrical power source 56, an electrical load (such as, an actuator 50, a downhole data gathering device, etc.), control circuitry 42 which controls activation of the electrical load, and a switch 60 which selectively permits electrical current flow between the electrical power source 56 and the control circuitry 42; and generating electricity downhole, thereby causing the switch 60 to permit the electrical current flow between the electrical power source 56 and the control circuitry 42.
The generating step can include flowing a fluid 24 downhole. The flowing step can include producing a thermal gradient at a thermoelectric generator 62 and/or producing motion at an electrical generator 62.
The fluid 24 may comprise a fracturing fluid and/or a stimulation fluid. Other types of fluid (such as, production fluid, cement, etc.) can be used.
The generating step may include displacing an object (such as, the magnetic device 38) downhole.
The method can also include, after the generating step, the control circuitry 42 causing the activation of the electrical load in response to a sensor 40 coupled to the control circuitry 42 detecting a predetermined stimulus. The stimulus could be a magnetic field, a certain number of magnetic fields, a specific magnetic field pattern, a pressure level or signal, etc. However, in some examples, the activating may be accomplished without use of a sensor to sense a predetermined stimulus.
A tool 16 for use in a subterranean well is also described above. In one example, the tool 16 can include an electrical power source 56 which stores electrical power, an electrical load, control circuitry 42 which controls activation of the electrical load, a switch 60 which selectively permits electrical current flow between the electrical power source 56 and the control circuitry 42, and an electrical generator 62.
The switch 60 may permit the electrical current flow between the electrical power source 56 and the control circuitry 42 in response to generation of electrical power by the electrical generator 62.
The tool 16 may also include a sensor 40. The control circuitry 42, in response to detection by the sensor 40 of a predetermined signal, can cause the activation of the electrical load, but only if the switch 60 permits electrical current flow between the electrical power source 56 and the control circuitry 42. The sensor 40 may comprise a magnetic field sensor.
The electrical power source 56 can comprise a battery. Other types of electrical power sources, such as charged capacitors, etc., can be used.
The electrical generator 62 may comprise a thermoelectric generator. The thermoelectric generator 62 can generate electricity in response to fluid 24 flow through a flow passage 36 of the tool 16. A thermal gradient could be produced in other ways, for example, Joule-Thomson cooling due to gas flow, setting of cement, etc. Other types of electrical generators may be used.
Another method of activating a downhole tool 16 in a subterranean well can comprise: displacing at least one of a fluid 24 and an object (such as the magnetic device 38) at the downhole tool 16 in the well, generating electricity downhole in response to the displacing, permitting electrical current flow between a downhole electrical power source 56 and a downhole control circuitry 42 in response to the generating step and, after the permitting step and in response to detection of a predetermined signal, the control circuitry 42 causing activation of a downhole electrical load (such as, the actuator 50, a heater, a data gathering device, etc.).
Causing the activation of the electrical load can include the control circuitry 42 permitting electrical current flow between the electrical power source 56 and the electrical load.
The displacing step can include producing a thermal gradient at the downhole tool 16. The displacing step can include producing movement (such as, vibration of the membrane 76) at the downhole tool 16.
If the displacing step comprises flowing the fluid 24, the fluid 24 may include a stimulation and/or a fracturing fluid. As mentioned above, other types of fluids may be used, as well.
Although various examples have been described above, with each example having certain features, it should be understood that it is not necessary for a particular feature of one example to be used exclusively with that example. Instead, any of the features described above and/or depicted in the drawings can be combined with any of the examples, in addition to or in substitution for any of the other features of those examples. One example's features are not mutually exclusive to another example's features. Instead, the scope of this disclosure encompasses any combination of any of the features.
Although each example described above includes a certain combination of features, it should be understood that it is not necessary for all features of an example to be used. Instead, any of the features described above can be used, without any other particular feature or features also being used.
It should be understood that the various embodiments described herein may be utilized in various orientations, such as inclined, inverted, horizontal, vertical, etc., and in various configurations, without departing from the principles of this disclosure. The embodiments are described merely as examples of useful applications of the principles of the disclosure, which is not limited to any specific details of these embodiments.
In the above description of the representative examples, directional terms (such as “above,” “below,” “upper,” “lower,” etc.) are used for convenience in referring to the accompanying drawings. However, it should be clearly understood that the scope of this disclosure is not limited to any particular directions described herein.
The terms “including,” “includes,” “comprising,” “comprises,” and similar terms are used in a non-limiting sense in this specification. For example, if a system, method, apparatus, device, etc., is described as “including” a certain feature or element, the system, method, apparatus, device, etc., can include that feature or element, and can also include other features or elements. Similarly, the term “comprises” is considered to mean “comprises, but is not limited to.”
Of course, a person skilled in the art would, upon a careful consideration of the above description of representative embodiments of the disclosure, readily appreciate that many modifications, additions, substitutions, deletions, and other changes may be made to the specific embodiments, and such changes are contemplated by the principles of this disclosure. For example, structures disclosed as being separately formed can, in other examples, be integrally formed and vice versa. Accordingly, the foregoing detailed description is to be clearly understood as being given by way of illustration and example only, the spirit and scope of the invention being limited solely by the appended claims and their equivalents.
