Extended power system for downhole tools

A power system may include a primary battery and a reserve battery coupled with an actuator to actuate a downhole tool to perform operations downhole in a wellbore. The reserve battery may include an electrolyte having a solid state at an ambient temperate the wellbore. The primary battery may be coupled to the thermal battery to activate a heat source of the reserve battery. The heat source may generate a heat that melts the electrolyte to a molten state and actuates the reserve battery to transmit power to the actuator.

TECHNICAL FIELD

The present disclosure relates generally to wellbore tools and, more particularly (although not exclusively), to power systems usable to extend the operational lifespan of downhole tools in a wellbore.

BACKGROUND

Various downhole tools can be utilized in a wellbore adjacent to a subterranean formation. In some wells, certain downhole tools may remain downhole permanently or indefinitely to perform intervaled or delayed operations in the wellbore. The length of time and the conditions downhole in the wellbore may each individually, or both collectively, deplete the lifespan of a battery (or other power source) powering an actuator of the downhole tool, which in turn may decrease the operational lifespan of the downhole tool. In some instances, wellbore operations may be temporarily halted to retrieve or replace the battery to allow the downhole tool to complete the wellbore operation.

DETAILED DESCRIPTION

Certain aspects and examples of the present disclosure relate to a power system including a primary battery and a thermally activated reserve battery operable to extend the operational lifespan of a downhole tool to perform operations in a wellbore subsequent to the primary battery depleting. In one example, the primary battery may include a lithium battery and the reserve battery may include a thermal battery. The lithium battery and the thermal battery may be coupled to an actuator of the downhole tool to provide power for actuating the downhole tool to perform operations in the wellbore. The lithium battery may also be coupled to the thermal battery to provide an electrical signal to a heat source of the thermal battery. The electrical signal may cause the heating source to increase in temperature to melt a solid-state electrolyte positioned between an anode and cathode of each cell of the thermal battery. Melting the electrolyte may allow electrical current to be drawn from the thermal battery and transmitted to the actuator to power the downhole tool to complete the wellbore operation.

In some aspects, the lithium battery may provide sole power to the actuator of the downhole tool to perform initial operations in the wellbore. The thermal battery may provide power to the actuator to perform a temporary or final operation in the wellbore after the lithium battery is depleted to an insufficient level to power the downhole tool. A switch positioned between the lithium battery and the thermal battery may close to allow the lithium battery to activate a heat source of the thermal battery to melt the solid-state electrolyte. In some aspects, the switch may be controlled by a processor. The processor may also actuate the lithium battery to power the actuator of the downhole tool. The processor may be coupled to a pressure sensor and a temperature sensor. An operator positioned at the surface of the wellbore may change the ambient pressure or temperature in the wellbore to a predetermined threshold to signal the processor to actuate the lithium battery to power the actuator.

Maintaining the electrolyte in a solid-state prior to activating the heat source may allow the thermal battery to remain inert without depleting the thermal battery prior to it being initiated by activating the heat source. In some aspects, the lithium battery may naturally deplete as the length of time that the downhole tool and the power system of the downhole tool are deployed in the wellbore increases. Further, the increased temperature of the downhole environment may exacerbate the natural depletion of the lithium battery. The power system's ability to use a thermal battery as a reserve battery to actuate the downhole tool may extend the operational lifespan of the downhole tool, resulting in saving of both cost and time. For example, the extended lifespan of the downhole tool may save labor costs and time in retrieving the power system of the downhole tool from the wellbore to replace the lithium battery. Minimizing the need to retrieve and replace the power system may also prevent unnecessary delays in the wellbore operations, resulting in additional savings in operational costs and time.

Detailed descriptions of certain examples are discussed below. These illustrative examples are given to introduce the reader to the general subject matter discussed here and are not intended to limit the scope of the disclosed concepts. The following sections describe various additional aspects and examples with reference to the drawings in which like numerals indicate like elements, and directional descriptions are used to describe the illustrative examples but, like the illustrative examples, should not be used to limit the present disclosure. The various figures described below depict examples of implementations for the present disclosure, but should not be used to limit the present disclosure.

Various aspects of the present disclosure may be implemented in various environments. For example,FIG. 1is a cross-sectional schematic diagram depicting an example of a wellbore environment100in which a wellbore tool including a power system according to some aspects of the present disclosure may be deployed. The wellbore environment100includes a wellbore102extending from a surface of the earth through various earth strata, including a subterranean formation106from which hydrocarbons may be extracted using wellbore operations. A tubing string108extends from the surface104to the subterranean formation106. In some aspects, the tubing string108may consist of segmented pipes and provide a conduit through which formation fluids, such as hydrocarbons produced from the subterranean formation, may travel from the wellbore102to the surface104.

The wellbore environment100may include at least one downhole tool110. The downhole tool110may be coupled to the tubing string108. In some aspects, downhole tool110may include any tool usable to perform wellbore operations downhole in the wellbore102. A non-limiting example of a downhole tool110includes a valve, such as an isolation barrier valve. An isolation barrier valve may isolate a zone of the subterranean formation106and provide a bi-directional seal subsequent to a completed fracturing and gravel packing operation in another zone of the subterranean formation106downhole of the isolation barrier valve. The isolation barrier valve may include a power system112including batteries usable to power an actuation mechanism, such as a shifting tool to open and close the valve. The power system112may provide power to the actuation mechanism to allow the isolation barrier valve to remain operational for an extended period. Although an isolation barrier valve is described, the downhole tool110may include any tool positioned downhole in the wellbore102to perform one or more short-term operations downhole in the wellbore102and remain in the wellbore102for an extended time to perform at least one long-term operation. In some aspects, the long-term operation may include an operation in the wellbore102occurring months or a year or more after deployment of the downhole tool110into the wellbore102.

FIG. 2is a block diagram of the power system112for the downhole tool110ofFIG. 1according to one aspect of the present disclosure. The power system112is a multi-battery system that includes a lithium battery200and a thermal battery202to power an actuator204of the downhole tool110. In some aspects, the lithium battery200may serve as the primary battery to transmit power to the actuator204to actuate the downhole tool110. The lithium battery200may be comprised of one or more lithium cells. In some aspects, each lithium cell may produce approximately 1.5 volts to 3.7 volts. The size of the lithium battery200may depend on the power necessary to actuate the downhole tool110. In some aspects, each cell may include an anode, cathode, and electrolyte. In one example, the anode may include metallic lithium, the cathode may include manganese dioxide, and the electrolyte may include a salt of lithium that is dissolved in an organic solvent. The lithium battery200may include at least 0.15 kilograms of lithium per kilowatt-hour. In some aspects, the lithium battery200may include a lithium-ion battery. Although the lithium battery200is described, the primary battery for the power system112may include any type of battery sufficient to provide power to actuator204to actuate the downhole tool110. For example, the primary battery may include a magnesium battery, aluminum-ion battery, or a dry cell battery.

The thermal battery202may serve as the secondary, or reserve, battery for the actuator204. The thermal battery202may include a solid-state electrolyte that maintains a solid state at ambient temperatures in the wellbore. The thermal battery202may remain inert when the electrolyte is in its solid state to preserve the full power capacity of the thermal battery202without the thermal battery202depleting over time. When the electrolyte melts, the thermal battery202may become conductive to allow current to traverse the cells of the thermal battery202to power the actuator204.

The thermal battery202includes a heat source206that may be activated to melt the electrolyte. In some aspects, the heat source may be activated by an electric current flowing from the lithium battery200to the thermal battery202. Non-limiting examples of the heat source may include an electric element, an electric match, an electro-explosive device, such as a squib, or a percussion cap. For example, an electric match may include a device that ignites a combustible compound (e.g., a pyrogen) in response to an electric current being applied to the electric match. A squib may include a small explosive device similar to dynamite that may detonate a tube of an explosive substance in response to an electric current being applied to electric leads of the squib. A percussion cap may include a small cylinder of copper or brass with a closed end containing a shock-sensitive explosive primer (e.g., fulminate of mercury). The explosion created by the heat source206may raise the temperature of the electrolyte304to the melting point of the electrolyte304to convert it to a molten state.

The thermal battery202may include one or more cells. In some aspects, the size of the thermal battery202may depend on the power necessary to actuate the downhole tool110.

FIG. 3is a cross-sectional schematic diagram depicting an example of a battery cell300for the thermal battery202ofFIG. 2according to one aspect of the present disclosure. Each battery cell300of the thermal battery202may include an anode302, an electrolyte304, and a cathode306. The electrolyte304may be positioned between the anode302and the cathode306to physically separate them and control the conductivity of the cell300. In some aspects, the cells300of the thermal battery202may be stacked in parallel or serially depending on the size of the thermal battery202. The anode302may serve as the positively charged electrode of the cell300. In some aspects, the anode302may comprise one of lithium, calcium, or magnesium. The cathode306may serve as the negatively charged electrode of the cell300. In some aspects, the cathode306may include a chromate or sulfide, such as potassium dichromate (K2Cr2O7), pyrite (FeS2), or cobalt sulfide (CoS2). The electrolyte304may include a material that is substantially non-conductive when in a solid state to prevent current from flowing from the cathode306to the anode302. In some aspects, the electrolyte304may include an inorganic salt, such as lithium chloride, potassium chloride, sodium, or lithium salt. The electrolyte304may have a melting point at which the electrolyte304may convert to a molten state and have conductive properties to allow electrons to flow between the anode302and the cathode306to produce an electrical current that may be used to power the actuator204ofFIG. 2. In some aspects, the melting point of the electrolyte304may be higher than an ambient temperature downhole in a wellbore. For example, the ambient temperature downhole in the wellbore may reach temperatures as high as 150 to 175 degrees Centigrade. In some aspects, the melting point may be approximately 300 degrees Centigrade to prevent the ambient temperature of the wellbore from prematurely activating the thermal battery202. In some aspects, the electrolyte304may be chemically manufactured to achieve a desired melting point sufficient for the expected temperatures downhole in the wellbore.

The battery cell300also includes a heat source206A. In some aspects, the heat source206A may be a component of the heat source206of the thermal battery202ofFIG. 2. For example, each battery cell300of the thermal battery202may include a heat source206A to collectively form the heat source206ofFIG. 2. Each heat source206A of each battery cell300may be connected by a fuse strip308that may extend across multiple cells of the thermal battery202. In some aspects, the fuse strip308may receive electric current from the lithium battery200ofFIG. 2and transmit the current to the heat source206A to cause the explosion for melting the electrolyte304. Although the heat source206A is shown as separated from the electrolyte304, the heat source206A may be positioned adjacent to the electrolyte304without departing from the scope of the present disclosure.

Returning toFIG. 2, the actuator204may include a device that causes the downhole tool110to operate in response to power received from the lithium battery200or thermal battery202. In some aspects, the actuator204may be coupled to the lithium battery200and the thermal battery202in parallel to allow the actuator204to receive power from each of the batteries200,202individually. Using the previous example of the downhole tool110being a valve, the actuator204may include a shifting tool configured to apply a force to open or close the valve in response to receiving an electrical signal from the lithium battery200or the thermal battery202. In other examples, the actuator204may include a motor or other actuating means for opening or closing the valve. In some aspects, the actuator204may include any device configured to actuate the downhole tool110in response to receiving power from the lithium battery or the thermal battery202.

The power system112also includes a processor208to actuate the lithium battery200to provide power to the actuator204of the downhole tool110, or, in certain instances, to actuate the lithium battery200to provide power to the thermal battery202to activate the heat source206. The processor208may also be coupled to a switch210positioned between the lithium battery200and the thermal battery202to control the flow of electrical current between the lithium battery and the thermal battery202. The processor208may represent a single processor or a set of processors. In some aspects, the processor208may be in communication with a computer-readable medium, such as a random access memory (RAM) coupled to the processor208. The processor208may execute computer-executable program instructions stored in memory. Non-limiting examples of the processor208include a microprocessor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), field programmable gate arrays (FPGAs), and state machines. In some aspects, the processor208may further comprise programmable electronic devices such as programmable logic controllers (PLCs), programmable interrupt controllers (PICs), programmable logic devices (PLDs), programmable read-only memories (PROMs), electronically programmable read-only memories (EPROMs or EEPROMs), or other similar devices.

In some aspects, the processor208may comprise, or may be in communication with, media, for example computer-readable storage media, that may store instructions that, when executed by the processor208, can cause the processor208to perform the steps described herein as carried out, or assisted, by a processor208. Examples of computer-readable media may include, but are not limited to, an electronic, optical, magnetic, or other storage device capable of providing a processor with computer-readable instructions. Other examples of media comprise, but are not limited to memory chips, ROM, RAM, ASICs, configured processors, or any other medium from which a computer processor can read. The processor208, and the processing, described may be in one or more structures, and may be dispersed through one or more structures. The processor may comprise code for carrying out parts of one or more of the methods (or parts of methods) described herein.

In some aspects, the processor208may be configured to monitor the power levels of the lithium battery200. For example, the processor208may additionally be coupled to the lithium battery200by a sensor for monitoring the lithium battery's200power levels. In response to the processor208determining that the power levels of the lithium battery200are insufficient to provide power to the actuator204to actuate the downhole tool110, the processor208may close the switch to complete an electrical flow path coupling the lithium battery200to the thermal battery202. In some aspects, the power necessary to heat the heat source206may be less than the power necessary to cause the actuator204to actuate the downhole tool110. In additional and alternative aspects, the processor208may include a timer and may adjust the switch from an open position to a closed position at a predetermined or preprogrammed time after deployment of the downhole tool110and the power system112.

The power system112also includes one or more sensors coupled to the processor208, including a pressure sensor212and a temperature sensor214. The pressure sensor212may include a pressure gauge, a pressure transducer, or other sensor means for monitoring the pressure in the wellbore102. The temperature sensor214may include a thermometer, a thermistor, a thermocouple, a resistance thermometer, other sensor means for monitoring the temperature in the wellbore102. The sensors212,214may be powered by the lithium battery200. In some aspects, the sensors212,214may also be powered by the thermal battery202. The sensors212,214may provide measurements of the pressure and temperature in the wellbore, respectively, to the processor208. The processor208may execute instructions to actuate the lithium battery based on a triggering condition determined by the pressure or temperature in the wellbore. In some aspects, an operator of the wellbore may control the power system112by intentionally adjusting the pressure or temperature in the wellbore outside of normal wellbore pressures or temperatures to trigger the processor208to actuate the lithium battery200to provide power to the actuator204. For example, the operator may adjust pressure gauges positioned at the surface104of the wellbore102ofFIG. 1to a predetermined pressure or pressure range to signal the processor208to actuate the lithium battery200. In another example, the operator may adjust the temperature by creating an explosion in the wellbore to raise the temperature to a predetermined temperature or temperature range to signal the processor208to actuate the lithium battery200. In additional and alternative aspects, the timer of the processor208may cause the triggering condition to actuate the lithium battery200. For example, the downhole tool may function at specific time intervals and the processor208may be preprogrammed to execute instructions to actuate the lithium battery at the specified time intervals. In some aspects, when the switch210is in the closed position, the triggering condition may cause the lithium battery200to heat source206of the thermal battery202, actuating the thermal battery202to provide power to the actuator204to actuate the downhole tool110.

FIG. 4is a flow chart of a process for actuating the downhole tool110ofFIG. 1according to one aspect of the present disclosure. The process is described with respect to the components ofFIGS. 1-3, though other implementations are possible without departing from the scope of the present disclosure.

In block400, a first triggering condition may be detected. In some aspects, the triggering condition may be detected by the processor208in response to a signal received from the pressure sensor212or the temperature sensor214. For example, the pressure sensor212may sense the pressure in the wellbore102and transmit signals to the processor208corresponding to the sensed pressure. Similarly, the temperature sensor214may sense the temperature in the wellbore102and transmit signals to the processor208corresponding to the sensed temperature. The processor208may receive the signals from the sensors212,214and detect a triggering condition when one of the temperature or pressure is at a predetermined level or within a predetermined range. In some aspects, the temperature or pressure in the wellbore102may be intentionally adjusted by an operator at the surface104of the wellbore102to signal to the processor208to cause the actuator204to actuate the downhole tool110. In other aspects, the triggering condition may correspond to a predetermine time. For example, the processor208may include a programmed timer corresponding to times or time intervals programmed by the operator for actuating the downhole tool110to perform an operation in the wellbore102. The processor208may detect the programmed time or time interval using the timer. Although the triggering conditions related to pressure, temperature and time are described separately, in some aspects, the processor208may detect a triggering condition in response to a combination of conditions monitored by the sensors212,214or the processor's208timer.

In block402, power is transmitted to actuate the downhole tool110in response to the triggering condition. In some aspects, the processor208, in response to detecting the triggering condition, may actuate the lithium battery200to transmit power to the actuator204to actuate the downhole tool110. In some aspects, the processor208may monitor the power level of the lithium battery200to determine if the power level is sufficient for the actuator204to actuate the downhole tool110. In response to determining that the power level is inefficient, the processor208may actuate the switch210to move to a closed position to complete an electric flow path between the lithium battery200and the thermal battery202to allow the thermal battery202to provide power to the actuator204when future triggering conditions are detected. In other aspects, the processor208may include a timer and actuate the switch to close in response to an indication from the timer.

In block404, a second triggering condition is detected. In some aspects, the processor may detect the second triggering condition in a same manner as described for detecting the first triggering event. For example, the pressure sensor212or the temperature sensor214may sense a temperature or pressure in the wellbore102intentionally manipulated by an operator at the surface104of the wellbore102to signal to the processor208to cause the actuator204to actuate the downhole tool110. In some aspects, the second triggering condition may occur after the first triggering condition. For example, the first triggering condition may occur soon after the downhole tool110and the power system112are deployed in the wellbore102to signal the processor208to cause the downhole tool110to perform one or more initial operations in the wellbore102. In some aspects, the second triggering condition may be detected days, months, or a year or more later than the first triggering condition. In additional aspects, the second triggering condition may occur after the lithium battery200has been depleted to a level no longer sufficient to power the actuator204. For example, the lithium battery200may be naturally depleted due to the elapsed time until the second triggering condition. In another example, the increased temperature in the wellbore102may exacerbate the depletion of the lithium battery200.

In block406, the heat source206of the thermal battery202is activated in response to the second triggering condition. In some aspects, the processor208may, in response to detecting the triggering condition, actuate the lithium battery200. The lithium battery200may be depleted and unable to provide sufficient power to the actuator204to actuate the downhole tool110. But, the lithium battery200may have sufficient power to activate the heat source206. Subsequent to the processor208actuating the lithium battery200in response to the second triggering condition, the lithium battery200may transmit an electric signal (e.g., a power voltage signal) to the heat source206to cause the heat source to heat up. The heat of the heat source206may melt the electrolyte304in each cell300of the thermal battery202from a solid state to a molten state. The molten state of the electrolyte304in each cell300may allow the thermal battery202to generate electrical current.

In block408, power is transmitted to actuate the downhole tool110. In some aspects, the power may be transmitted by the thermal battery202to the actuator204to actuate the downhole tool110. In some aspects, the power transmitted by the thermal battery202may allow the actuator204to actuate the downhole tool110to perform a signal wellbore operation. In other aspects, the power transmitted by the thermal battery202may allow the actuator204to actuate the downhole tool110temporarily for a limited amount of time (e.g., minutes or one to two hours).

In some aspects, systems and methods may be provided according to one or more, or a combination of any portion, of the following examples:

A power system for a downhole tool may include a primary battery. The power system may also include a reserve battery coupled to the primary battery. The reserve battery may include an anode. The reserve battery may also include a cathode. The reserve battery may also include a solid-state electrolyte disposed between the anode and the cathode and meltable by a heat source to change from a solid state, at which the solid-state electrolyte prevents the reserve battery from providing power to an actuator, to a molten state, at which the reserve battery provides power to the actuator to actuate a downhole tool.

The power system of example 1 may also include a processor couplable to the primary battery to actuate the primary battery in response to a triggering condition. The triggering condition may include at least one of a predetermined temperature in a wellbore or a predetermined pressure in the wellbore.

The power system of examples 1-2 may also include a pressure sensor coupled to the processor and positionable to monitor a pressure in the wellbore.

The power system of examples 1-3 may also include a temperature sensor coupled to the processor and positionable to monitor a temperature in the wellbore.

The power system of examples 1-4 may also include a switch communicatively coupled to the processor and positioned between the primary battery and the reserve battery.

The power system of examples 1-5 may also include a processor communicatively couplable to the primary battery to monitor a power level of the primary battery.

The power system of examples 1-6 may feature the downhole tool being a valve, wherein the actuator is positionable proximate to the valve to open or close the valve.

The power system of examples 1-7 may feature the heat source including one of an electric element, an electric match, a squib, or a percussion cap.

The power system of examples 1-8 may feature the solid-state electrolyte including at least one of lithium chloride, potassium chloride, or sodium.

The power system of examples 1-9 may feature the primary battery being a lithium battery.

A method for actuating a downhole tool may include detecting, by a sensor, a first triggering condition. The method may also include transmitting power, by a first battery, to actuate the downhole tool to perform a first wellbore operation in response to the first triggering condition in a wellbore. The method may also include detecting, by the sensor, a second triggering condition, the second triggering condition occurring after the first triggering condition. The method may also include activating, by the first battery, a heat source of a second battery to actuate the second battery in response to the second triggering condition in the wellbore. The method may also include transmitting power, by the second battery, to actuate the downhole tool to perform a second wellbore operation.

The method of example 11 may feature the sensor including a pressure sensor. Detecting the first triggering condition may include detecting, by the pressure sensor, a pressure in the wellbore generated by an operator as a signal to actuate the downhole tool to perform the first wellbore operation.

The method of examples 11-12 may feature detecting the second triggering condition to include detecting, by the pressure sensor, a second pressure in the wellbore generated by the operator as a second signal to actuate the downhole tool to perform the second wellbore operation.

The method of examples 11-13 may feature activating the heat source of the second battery to include melting, by heat generated from the heat source, a solid-state electrolyte positioned between an anode and a cathode of the second battery to actuate the second battery.

The method of example 14 may feature the solid-state electrolyte including at least one of lithium chloride, potassium chloride, or sodium.

The method of examples 11-15 may feature activating the heat source of the second battery to include transmitting an electric signal from the first battery to the heat source. The heat source may include one of an electric element, an electric match, a squib, or a percussion cap.

The method of examples 11-16 may feature the first battery being a lithium battery.

A system may include a downhole tool positionable in a wellbore. The system may also include an actuator coupled to the downhole tool. The system may also include a thermal battery coupled to the actuator. The thermal battery may include an anode. The thermal battery may also include a cathode. The thermal battery may also include a heat source. The thermal battery may also include a solid-state electrolyte disposed between the anode and the cathode and meltable by the heat source to change from a solid state, at which the solid-state electrolyte prevents the thermal battery from providing power to the actuator, to a molten state at which the thermal battery provides power to the actuator to actuate the downhole tool. The system may also include a switch coupled to the thermal battery and movable between an open position to prevent an electric signal from actuating the heat source and a closed position to allow the electric signal to activate the heat source. The system may also include a processor coupled to the switch, wherein the switch is actuatable by the processor.

The system of example 18 may also include a lithium battery coupled to the processor and the thermal battery. The switch may be positioned between the lithium battery and the thermal battery. The lithium battery may be actuatable by the processor to generate the electric signal.

The system of examples 18-19 may feature the downhole tool being a valve. The actuator may include a shifting tool positionable proximate the valve to open and close the valve.

The foregoing description of the examples, including illustrated examples, has been presented only for the purpose of illustration and description and is not intended to be exhaustive or to limit the subject matter to the precise forms disclosed. Numerous modifications, adaptations, uses, and installations thereof can be apparent to those skilled in the art without departing from the scope of this disclosure. The illustrative examples described above are given to introduce the reader to the general subject matter discussed here and are not intended to limit the scope of the disclosed concepts.