The subject disclosure relates to the field of downhole electrical energy generation. More specifically, the subject disclosure relates to techniques for electrical energy generation from electro chemical reactions and/or nuclear decay for powering devices in downhole environments.
There are many different approaches to the generation of electrical energy which include: 1) using piezoelectric devices to convert vibration into electric energy, 2) converting energy from ocean waves into electric energy, 3) converting coriolis effect into energy, 4) using the electrical response phenomenon of electrostrictive polymers to harvest electrical power from the general movement of objects e.g. human walking motion, 5) converting EM radiation into electrical energy, 6) energy scavengers which adjust their frequency by altering liquid distributions on a beam, 7) collecting acoustic energy and transforming the acoustic energy into electrical energy for use by a sensor, 8) transmitting energy by pressure oscillations in a fluid, and 10) different systems for storing the energy and using the stored energy to power sensors.
This summary is provided to introduce a selection of concepts that are further described below in the detailed description. This summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used as an aid in limiting the scope of the claimed subject matter.
In accordance with some embodiments an apparatus and a method for converting electrochemical energy to electrical energy downhole is described. The apparatus includes a first electrode and a second electrode, the first and second electrodes being adapted and arranged to be deployed downhole and to form an anode and a cathode respectively upon exposure to an acidic fluid in a downhole environment, thereby generating electrical energy; and a downhole device adapted and arranged to be energized by the generated electrical energy while in a downhole environment. According to some embodiments the downhole device such as a sensor and/or a burrowing device, is less than about 1 mm in size and can be deployed via pumping into the formation.
According to some embodiments an apparatus for converting nuclear energy to electrical energy downhole is described. A first conductor contains a decaying radioactive isotope (such as 63Ni and/or 45Ca) which emits primarily electrons; a second conductor adapted and arranged to accept the electrons emitted by the first conductor and the first and second conductors adapted and arranged so as to form a capacitor that is charged by the emitted and accepted electrons, and to be deployed in a downhole environment; and a downhole device adapted to be energized using electrical energy stored in the capacitor. According to some embodiments, the apparatus is untethered with the surface such that electrical power from the surface is unavailable to the device
Further features and advantages will become more readily apparent from the following detailed description when taken in conjunction with the accompanying drawings.
Specific details are given in the following description to provide a thorough understanding of the embodiments. However, it will be understood by one of ordinary skill in the art that the embodiments may be practiced without these specific details. For example, systems, processes, and other elements in the invention may be shown as components in block diagram form in order not to obscure the embodiments in unnecessary detail. In other instances, well-known processes, structures, and techniques may be shown without unnecessary detail in order to avoid obscuring the embodiments. Further, like reference numbers and designations in the various drawings indicate like elements.
Also, it is noted that individual embodiments may be described as a process which is depicted as a flowchart, a flow diagram, a data flow diagram, a structure diagram, or a block diagram. Although a flowchart may describe the operations as a sequential process, many of the operations can be performed in parallel or concurrently. In addition, the order of the operations may be re-arranged. A process may be terminated when its operations are completed, but could have additional steps not discussed or included in a figure. Furthermore, not all operations in any particularly described process may occur in each embodiment. A process may correspond to a method, a function, a procedure, a subroutine, a subprogram, etc. When a process corresponds to a function, its termination corresponds to a return of the function to the calling function or the main function.
Furthermore, embodiments of the invention may be implemented, at least in part, either manually or automatically. Manual or automatic implementations may be executed, or at least assisted, through the use of machines, hardware, software, firmware, middleware, microcode, hardware description languages, or any combination thereof. When implemented in software, firmware, middleware or microcode, the program code or code segments to perform the required tasks may be stored in a machine readable medium. A processor(s) may perform the required tasks.
According to some embodiments, procedures and devices are described for electric energy generation from electrochemical use of substances for powering downhole devices. According to some other embodiments procedures and devices are described for electric energy generation from nuclear decay for powering downhole devices. According to some embodiments, the types of devices being powered are untethered or otherwise cannot benefit from direct power transmission from the surface. Examples of devices include small devices in downhole environments. Other examples of devices are sensors and other hardware such as flow control valves installed during completion. According to one example permanent and/or semi-permanent monitoring sensors make use of the energy generation techniques described herein.
According to some embodiments, methods and devices are described for electric energy generation from nuclear decay for powering devices, for example, small devices in downhole environments. The devices extract electrical energy from nuclear decay that produces charged particles. In such devices, the procedure uses a decaying isotope that emits kinetically-energetic charged particles which is placed on one side of a capacitor. The kinetic energy of the particles carries them to the opposing side of the capacitor where they are collected, thereby charging the capacitor. The process continues until the potential energy across the charged capacitor gap matches the kinetic energy of the emitted particles. As the capacitor is discharged, its voltage decreases, and charging resumes until the isotope has fully decayed.
According to some other embodiments, methods and devices are described for electric energy generation from electrochemical use of acid for powering devices, for example, small devices in downhole environments. The devices have two different metal electrodes and when the devices are immersed in an acidic electrolyte, the devices generate electric energy. According to some embodiments, the devices do not carry the acidic electrolyte. Rather, acid is injected into the well for several operations, as is common in the oilfield industry.
According to some embodiments, various devices such as one or more of sensor 140, valves 116-1, 116-2, 116-3, 142, and small devices 150 and 152 make use of energy generating using electrochemical reactions and/or nuclear decay, as will be described in further detail herein. In the case of electrochemical reaction energy generation, according to some embodiments, an acid is pumped into the wellbore 136 and into formation 102. Arrows 136-1, 136-2, 136-3 and 136-4 show the path of acid influx. According to some embodiments the acid is introduced as part of a treatment or other servicing of the wellbore, but is also beneficially used in the generation of electrical energy.
Referring to
According to some embodiments, it has been found that the isotope 63Ni possess safety properties including: (1) the isotope is a beta emitter (that is, it emits electrons); (2) the isotope decays to a stable atom; and (3) the emitted beta particles have relatively low energy that minimize the secondary emission of x-rays during collection. According to some embodiments, the isotope 45Ca is used which is a weak alpha emitter. According to some embodiments, a combination of isotopes is used. The half-life of 63Ni in embodiments is 101 years. The specific power of 63Ni is near 2.4 mW/g, with an optimal collection voltage of 17 kV. The isotope 45Ca has a shorter half-life of 163 days, and a specific power near 2.9 W/g, with an optimal collection voltage of 65 kV. The optimal collection voltage of these embodiments is very high compared to the voltage of typical circuitry being powered. Accordingly, the use of one or more of these embodiments is an energy source enabler of many devices. Example devices include: autonomous electrical and electromechanical devices for oil-drilling, logging, sand control, sensing, actuation, etc. The described embodiments thus provide a simple, long-life, low-cost, power source of electrical energy that is suitable for powering small autonomous devices such as shown in
Thus, according to some embodiments a procedure and a device for electric energy generation from nuclear decay for powering devices is provided, for example, small devices in downhole environments. According to some embodiments, devices powered according to the described techniques are inserted into the formation that surrounds an oil well while they are connected to micro devices that are powered by the generation system. The devices can be burrowing systems, micro robots, sensors, actuators of mechanisms such as deployable structures or others, etc.
Further details regarding electrical energy generation from electrochemical reactions will now be provided. The generation device according to these embodiments has two different metal electrodes. When the device is immersed in a medium that is impregnated in acidic electrolyte, the device generates electrical energy. According to some embodiments, the device does not carry the acidic electrolyte with it. In such a device, the procedure relies on having electrons moving from one of its metal electrodes to the other. The acid works as a bridge that facilitates the chemical reaction between anode, one of the metals, and the cathode, the other metal.
In oil exploration, acid is injected into the well for several operations. According to some embodiments, the device is immersed in the downhole formation fluid impregnated with acid. The device uses the acid as one of the components to provoke the electrochemical energy transformation. The energy transformation will occur when the electric circuit is closed. Advantageously, the electrodes are consumed when the circuit is closed. Some embodiments of this invention consist of the two electrodes separated by a volume that contains sensors, transmitters, electromechanical devices, etc.
According to some embodiments, the energy transformation process continues until the electrodes are consumed or the acid is not available in the environment in which the device is submerged or inserted.
Environments in which acid is present make this a particularly attractive energy source enabler of many devices. For example, the electrochemical generation techniques described herein can be used with autonomous electrical and electromechanical devices for oil-drilling, logging, sand control, sensing, actuation, and burrowing robotic devices, etc.
According to some embodiments, the generator can be used as an energizing module of locomotion systems, i.e. burrowing devices such as shown in
According to some embodiments, one or more of the techniques discussed in the following references which relate to nuclear battery technology can be used in connection with the teachings herein: U.S. Pat. No. 6,097,188; U.S. Patent Application Publ. No. 2007/0018110; U.S. Pat. Nos. 4,618,470; and 5,606,213, each of which is incorporated by reference herein.
Although only a few example embodiments have been described in detail above, those skilled in the art will readily appreciate that many modifications are possible in the example embodiments without materially departing from this invention. Accordingly, all such modifications are intended to be included within the scope of this disclosure as defined in the following claims. In the claims, means-plus-function clauses are intended to cover the structures described herein as performing the recited function and not only structural equivalents, but also equivalent structures. Thus, although a nail and a screw may not be structural equivalents in that a nail employs a cylindrical surface to secure wood parts together, whereas a screw employs a helical surface, in the environment of fastening wood parts, a nail and screw may be equivalent structures. It is the express intention of the applicant not to invoke 35 U.S.C. §112, paragraph 6 for any limitations of any of the claims herein, except for those in which the claim expressly uses the words “means for” together with an associated function.
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