Patent Application
20060102353
Not Applicable.
Not Applicable.
To drill a well, a drill bit bores thousands of feet into the crust of the earth. The drill bit typically extends downward from a drilling platform on a string of pipe, commonly referred to as a “drill string.” The drill string may be jointed pipe or coiled tubing, through which drilling fluid is pumped to cool and lubricate the bit and lift the drill cuttings to the surface. At the lower, or distal, end of the drill string is a bottom hole assembly (BHA), which includes, among other components, the drill bit.
In order to obtain measurements and information from the downhole environment while drilling, the BHA includes electronic instrumentation. Various tools on the drill string, such as logging-while-drilling (LWD) tools and measurement-while-drilling (MWD) tools incorporate the instrumentation. Such tools on the drill string contain various electronic components incorporated as part of the BHA. These electronic components generally consist of computer chips, circuit boards, processors, data storage, power converters, and the like.
Downhole tools must be able to operate near the surface of the earth as well as many thousands of feet below the surface. Environmental temperatures tend to increase with depth during the drilling of the well. As the depth increases, the tools are subjected to a severe operating environment. For example, downhole temperatures are generally high and may even exceed 200° C. In addition, pressures may exceed 20,000 psi. There is also vibration and shock stress associated with operating in the downhole environment, particularly during drilling operations.
The electronic components in the downhole tools also internally generate heat. For example, a typical wireline tool may dissipate over 100 watts of power, and a typical downhole tool on a drill string may dissipate over 10 watts of power. While performing drilling operations, the tools on the drill string typically remain in the downhole environment for periods of several weeks. In other downhole applications, drill string electronics may remain downhole for as short as several hours to as long as one year. For example, to obtain downhole measurements, tools are lowered into the well on a wireline or a cable. These tools are commonly referred to as “wireline tools.” However, unlike in drilling applications, wireline tools generally remain in the downhole environment for less than twenty-four hours.
A problem with downhole tools is that when downhole temperatures exceed the temperature of the electronic components, the heat cannot dissipate into the environment. The heat may accumulate internally within the electronic components and this may result in a degradation of the operating characteristics of the component or may result in a failure. Thus, two general heat sources must be accounted for in downhole tools, the heat incident from the surrounding downhole environment and the heat generated by the tool components, e.g., the tool's electronics components.
While the temperatures of the downhole environment may exceed 200° C., the electronic components are typically rated to operate at no more than 125° C. Thus, exposure of the tool to elevated temperatures of the downhole environment and the heat dissipated by the components may result in the degradation of the thermal failure of those components. Generally, thermally induced failure has at least two modes. First, the thermal stress on the components degrades their useful lifetime. Second, at some temperature, the electronics may fail and the components may stop operating. Thermal failure may result in cost not only due to the replacement costs of the failed electronic components, but also because electronic component failure interrupts downhole activities. Trips into the borehole also use costly rig time.
In general, there are at least two methods for managing the temperature of thermal components in a downhole tool. One method is a heat storing temperature management system. Heat storing temperature management involves removing heat from the thermal component and storing the heat in another element of the heat storing temperature management system, such as a heat sink. Another method is a heat exhausting temperature management system. Heat exhausting temperature management involves removing heat from the thermal component and transferring the heat to the environment outside the heat exhausting temperature management system. The heat may be transferred to the drill string or to the drilling fluid inside or outside the drill string.
A traditional method of managing the temperature of thermal components in a downhole tool using a heat exhausting system involves modest environmental temperatures such that the electronics operate at a temperature above the environmental temperature. In modest environments, the electronics may be thermally connected to the tool housing. The thermal connection allows the heat to dissipate to the environment by the natural heat transfer of conduction, convection, and/or radiation. This approach is limited by the temperature gradient between the electronics and the environment.
A traditional method of managing the temperature of thermal components in a downhole tool using a heat storage system in harsh thermal environments is to place the electronics on a chassis in an insulated vacuum flask. The vacuum flask acts as a thermal barrier to retard heat transfer from the downhole environment to the electronics. However, thermal flasks are heat storage systems that only slow the harmful effects of thermal failure. Because of the extended periods downhole in both wireline and drilling operations, insulated flasks may not provide sufficient thermal management for the electronic components for extended periods. Specifically, the flask does not remove the heat generated internally by the electronic components. A thermal mass, such as a eutectic material, can be included in the flask to absorb heat from the downhole environment as well as the heat generated internally by the electronics. However, both the thermal flask and the thermal mass are only used to thermally manage the temperature of the interior of the electronics compartment. Because the discrete components may internally generate heat, they may remain at a higher temperature than the average temperature of the interior of the electronics compartment. Thus, although the average temperature of the interior of the compartment may remain at a desired level, discrete components may exceed their desired operating temperatures.
Another temperature management method for downhole electronics proposes a vapor compression temperature management system using water or other suitable liquid; e.g., FREON®. In this method, liquid in one tank is thermally coupled with the electronics chassis of the downhole tool. The liquid absorbs heat via the heat exchanger from the downhole environment and the electronics, where the electronics are isolated from the liquid, and begins to vaporize. For example, water would begin to vaporize at 100° C. so long as the pressure of the tank is maintained at 1.01×105 Pa (14.7 psi). To maintain the pressure, the steam is removed from the tank and compressed and stored in a second tank, which is at or near the temperature of the downhole environment. However, sufficient steam must be removed from the first tank with a compressor to maintain the pressure at 1.01×105 Pa. Otherwise, the boiling point of the liquid will rise and thus raise the temperature of the electronics chassis in the first tank.
In practice, vaporization temperature management has significant problems. First, a compressor must be supplied that is able to compress the vapor to a pressure greater than the saturation pressure of the vapor at the temperature of the downhole environment; e.g., 1.55×106 Pa (225 psi) at 200° C. for water. Second, the method does not isolate the thermal components but instead attempts to cool the entire electronics region. While the average temperature of the region may remain at 100° C., the temperature of the discrete electronic components may be higher because they may internally generate heat. Additionally, due to the typically low efficiency of most temperature management systems and the typically relatively high amount of heat to be extracted, substantial power may be required by the system. This power is typically provided from downhole power generation devices such as turbine alternators. However, the downhole power generation devices are typically powered by drilling fluid being pumped through the inside of the drill string during drilling. At times during the drilling process, the pumping may be stopped to perform various tasks such as adding pipe to or removing pipe from the drill string. When the pumping is stopped, the downhole power generation devices are unable to supply power to the heat exhausting temperature management system. Thus, although temperature management is still required, those heat exhausting temperature management systems that require a source of power are unable to cool the thermal components when pumping is stopped because of the loss of power. Even if batteries are provided downhole, they are limited in the duration for which they can provide power to the heat exhausting temperature management system.
Another temperature management method proposes a sorbent temperature management system. This method again uses the evaporation of a liquid that is thermally connected via heat exchanger with the thermal components to manage the temperature of the components. Instead of using a compressor to remove the vapor, this method uses desiccants in a second tank to absorb the vapor as it evaporates in a first tank, thus providing heat storage while requiring no input power. However, the desiccants must absorb sufficient vapor in order to maintain a constant pressure in the first tank. Otherwise, the boiling point of the liquid will rise as the pressure in the lower tank rises.
However, prior sorbent temperature management systems manage the temperature of the entire electronics region, not the discrete thermal components. Thus, because of internal heat generation, the thermal components may remain at a higher temperature than the average temperature of the entire thermal component region. Second, the desiccants must absorb sufficient vapor in order to maintain a constant pressure in the first tank. Otherwise, the liquid will evaporate at a higher temperature and thus the temperature in the first tank will increase. Further, the amount of water in the first tank limits the system. Once all the water evaporates, the system no longer functions.
Another heat exhausting temperature management method involves a downhole thermoelectric refrigeration system comprising a cold heat exchanger and a hot heat exchanger thermally coupled by semiconductor materials. With the thermoelectric refrigeration system, the cold heat exchanger of the temperature management system is thermally coupled with the thermal components.
Due to the typically low efficiency of thermoelectric refrigeration temperature management systems and the typically relatively high amount of heat to be extracted, substantial power is required by the temperature management system. This power can typically only be provided from downhole power generation devices such as turbines and alternators. However, the downhole power generation devices are typically powered by drilling fluid being pumped through the inside of the drill string during drilling. At times during the drilling process, the pumping is stopped to perform various tasks such as adding pipe to or removing pipe from the drill string. When the pumping is stopped, the downhole power generation devices are unable to supply power to the heat exhausting temperature management system. Thus, although temperature management is still required, the thermoelectric refrigeration systems are unable to cool the thermal components when pumping is stopped because of the loss of power. Even if batteries are provided downhole, they are limited in the duration for which they can provide power to the thermoelectric refrigeration system.
Another temperature management method involves a downhole thermoacoustic temperature management system. An example of a downhole thermoacoustic temperature management system is described in U.S. Pat. No. 5,165,243, issued Nov. 24, 1992 and entitled “Compact Acoustic Refrigerator”, hereby incorporated herein by reference for all purposes. The compact acoustic refrigeration system cools components, e.g., electrical circuits, in a downhole environment. The system includes an acoustic engine that includes first thermodynamic elements for generating a standing acoustic wave in a selected medium. The system also includes an acoustic refrigerator that includes second thermodynamic elements located in the standing wave for generating a relatively cold temperature at a first end of the second thermodynamic elements and a relatively hot temperature at a second end of the second thermodynamic elements. A resonator volume cooperates with the first and second thermodynamic elements to support the standing wave. To accommodate the high heat fluxes required for heat transfer to/from the first and second thermodynamic elements, first heat pipes transfer heat from the heat load to the second thermodynamic elements and second heat pipes transfer heat from the first and second thermodynamic elements to the downhole environment.
For a more detailed description of the embodiments, reference will now be made to the following accompanying drawings:
The present invention relates to a thermal component temperature management system and includes embodiments of different forms. The drawings and the description below disclose specific embodiments with the understanding that the embodiments are to be considered an exemplification of the principles of the invention, and are not intended to limit the invention to that illustrated and described. Further, it is to be fully recognized that the different teachings of the embodiments discussed below may be employed separately or in any suitable combination to produce desired results. The term “couple”, “couples”, or “thermally coupled” as used herein is intended to mean either an indirect or a direct connection. Thus, if a first device couples to a second device, that connection may be through a direct connection; e.g., via conduction through one or more devices, or through an indirect connection; e.g., via convection or radiation. The term “temperature management” as used herein is intended to mean the overall management of temperature, including maintaining, increasing, or decreasing temperature and is not meant to be limited to only decreasing temperature.
The temperature management system 10 manages the temperature of at least one thermal component 12 that may, e.g., be mounted on at least one board 18 in the downhole tool 14. The thermal component 12 comprises, but is not limited to, heat-dissipating components, heat-generating components, and/or heat-sensitive components. An example of a thermal component 12 may be an integrated circuit, e.g., a computer chip, or other electrical or mechanical device that is heat-sensitive or whose performance is deteriorated by high temperature operation, or that generates heat. The board 18 is in turn mounted on a chassis (not illustrated) and installed within a cavity 15 of the downhole tool 14.
Heat Exchanger
The temperature management system 10 further comprises a heat exchanger 20 thermally coupled with the thermal component 12. In one embodiment, the heat exchanger 20 is thermally coupled via a conductive path to the thermal component 12. However, in other embodiments, the heat exchanger 20 may be thermally coupled with the thermal component 12 by radiation or convection. The heat exchanger 20 may be any appropriate type of heat exchanger, such as a conduction heat exchanger that uses heat conduction to transfer the heat through solids. The heat exchanger 20 may also comprise multiple layers of different materials, e.g., copper flow tubes with aluminum fins or plates. The heat exchanger 20 may also be a micro-capillary heat exchanger. The micro-capillary heat exchanger may also be a micro-channel, cold plate heat exchanger with stacked plates enclosed in a housing. The heat exchanger may also be a liquid cold plate heat exchanger.
Heat Storing Temperature Management System
The temperature management system 10 further comprises a heat storing temperature management system 11 thermally coupled with the heat exchanger 20. The heat storing temperature management system 11 removes heat from the thermal component 12 through the heat exchanger 20 and stores the removed heat in within the heat storing temperature management system 11. The heat storing temperature management system 11 comprises a heat sink 22 comprising a phase change material for storing the removed heat. The phase change material is designed to take advantage of the heat absorbed during the phase change at certain temperature ranges; e.g., a eutectic material. Eutectic material is an alloy having a component composition designed to achieve a desired melting point for the material. The desired melting point takes advantage of latent heat of fusion to absorb energy. Latent heat is the energy absorbed by the material as it changes phase from solid into liquid. Thus, when the material changes its physical state, it absorbs energy without a change in the temperature of the material. Therefore, additional heat will only change the phase of the material, not its temperature. To take advantage of the latent heat of fusion, the eutectic material may have a melting point below the desired maintenance temperature of the thermal component 12. The heat sink 22 may also comprise other types of thermal mass, such as copper, to store removed heat.
The heat sink 22 may be stored in a jacket 24 capable of withstanding downhole temperatures and shock conditions. For example, the jacket 24 can be a stainless steel container. Because the heat sink 22 may undergo a phase change, the jacket 24 may also be capable of withstanding the contraction and/or expansion of the heat sink 22.
Thermal Conduit System
The heat storing temperature management system 11 also comprises a thermal conduit system 26 for thermally coupling the heat exchanger 20 and the heat sink 22. The temperature gradient between thermal component 12 and the heat sink 22 is such that the heat sink 22 absorbs the heat from the thermal component 12 through the heat exchanger 20 and the thermal conduit system 26. The thermal conduit system 26 comprises a thermally conductive material for transferring heat from the heat exchanger 20 to the heat sink 22. The thermal conduit system 26 may alternatively comprise a coolant fluid conduit system that transfers the removed heat using a coolant fluid in a closed-loop or an open-loop system. The coolant fluid is thermally coupled to the heat exchanger 20 and the heat sink 22 and transfers heat absorbed from the heat exchanger 20 to the heat sink 22, returning the coolant fluid to a lower temperature. The thermal conduit system 26 maintains the coolant fluid separate from the heat sink 22 material. The path of the thermal conduit system 26 through the heat sink 22 may be straight or tortuous depending on the performance specifications of the temperature management system 10. For example, the thermal conduit system 26 may flow helically into the heat sink 22, reverse, and then flow helically out of the heat sink 22. The thermal conduit system 26 may also transfer heat to the heat sink 22 using any other suitable means. The fluid may be moved within the thermal conduit system 26 using a fluid transfer device, e.g., a fluid pump. Alternatively, the fluid in the thermal conduit system 26 flows via convection, i.e., by maintaining a temperature differential between any two-points in the system. The thermal component 12 may be immersed in fluid, e.g., water or a fluorinated organic compound, e.g., FLUORINERT®, or any other thermally conductive fluid. The fluid the thermal component 12 is immersed in need not be the same fluid as the coolant fluid in the thermal conduit system 26. For example, the thermal component 12 may be immersed in silicone oil or any other suitable fluid. Additionally, the thermal component 12 may be immersed in a fluid regardless of whether the thermal conduit system 26 is a fluid thermal conduit system. The fluid thermal conduit system 26 may be a single-phase or multiple-phase system. Examples of thermal conduit systems are discussed in U.S. patent application Ser. No. 10/602,236, filed Jun. 24, 2003 and entitled “Method and Apparatus for Managing the Temperature of Thermal Components”, hereby incorporated herein by reference for all purposes. Alternatively, the thermal conduit system may thermally couple more than one thermal component 12 to the heat sink 22. Also alternatively, the heat removed from the thermal component 12 may be absorbed directly by the heat sink 22; e.g., via conduction by being in contact with the heat exchanger, or via convection or radiation from the heat exchanger to the heat sink.
Thus, with the exception of the alternatives requiring a fluid transfer device, the heat storing temperature management system 11 requires no power to remove heat from the thermal component 12. Even with the fluid transfer device, the heat storing temperature management system 11 would require low amounts of power, e.g., less than 500 mw, and would be able to operate for approximately 9 hours on a conventional 9 volt battery.
Heat Exhausting Temperature Management System
The temperature management system 10 also comprises a heat exhausting temperature management system 40 thermally coupled with the heat storing temperature management system 11. The heat exhausting temperature management system 40 removes heat from the heat storing temperature management system 11 and transfers the heat to the environment outside the temperature management system 10.
In one embodiment, as illustrated in
The cold plate 44 of the heat exhausting temperature management system 40 is thermally coupled with the heat sink 22 of the heat storing temperature management system 11. The heat exhausting temperature management system 40 removes heat from the heat sink 22 at the cold plate 44 and transfers the removed heat to the hot plate 46. From the hot plate 46, the heat is then transferred to the environment outside the temperature management system 10. The heat may be transferred to the drill string 16, the drilling fluid traveling in the annulus 52 between the downhole tool 14 and the formation 17, or the drilling fluid being pumped through the drill string 16 and the downhole tool 14. The heat may be transferred from the hot plate 46 to the environment through conduction or through convection or radiation, or any combination of direct and indirect transfer. The heat exhausting temperature management system 40 allows removed heat to be transferred to the drilling fluid even though the drilling fluid may be at a higher temperature than the thermal component 12. The heat exhausting temperature management system 40 may also comprise more than one thermoelectric cooler thermally coupled with the heat storing temperature management system 11. Instead of a thermoelectric cooler, alternatively the heat exhausting temperature management system 40 may comprise a thermoacoustic system, a vapor compression system, or other suitable heat pumping device.
Power for the thermal component 12 and the thermoelectric cooler 40 may be supplied by a turbine alternator 42, which is driven by the drilling fluid pumped through the drill string 16. The turbine alternator 16 may be of the axial, radial, or mixed flow type. Alternatively, the alternator 42 may be driven by a positive displacement motor driven by the drilling fluid, such as a Moineau-type motor.
If the heat exhausting temperature management system 40 is powered primarily by, e.g., the turbine alternator 42, it may operate during pumping of drilling fluid through the drill string 16 and for short time periods with the pumps off. With the pumps on, the heat exhausting temperature management system 40 removes heat from the heat storing temperature management system 11 and allows the temperature management system 10 to maintain heat removal from the thermal component 12. There are, however, periods when drilling fluid is not pumped through the drill string 16. During these times, the heat exhausting temperature management system 40 may not be operational, unless there is some other source of power. However, even if the heat exhausting temperature management system 40 is not operating, the heat storing temperature management system 11 is able to remove heat from the thermal component 12 and store the removed heat the heat sink 22. Once drilling fluid flow is restored, the heat exhausting temperature management system 40 will then remove the stored removed heat from the heat sink 22. Thus, the heat storing temperature management system 11 and the heat exhausting temperature management system 40 combine to manage the temperature of the thermal component 12.
Alternatively, when the power source 36 is on, the heat exhausting temperature management system 40 may be operated by a control system that determines when the heat exhausting temperature management system 40 operates. The control system is represented by the flow chart shown in
Thermal Barrier
The temperature management system 10 may alternatively further comprise a thermal barrier 50 enclosing the heat storing temperature management system 11, the heat exchanger 20, and the thermal component 12. The thermal barrier 50 thus separates the heat storing temperature management system 11, the heat exchanger 20, and the thermal component 12 from the downhole environment. The thermal barrier 50 may also enclose only a portion of the heat storing temperature management system 11. The thermal barrier 50 hinders heat transfer from the outside environment to the heat storing temperature management system 11 and the thermal component 12. By way of non-limiting example, the barrier 50 may be an insulated vacuum “flask”, a vacuum “flask” filled with an insulating solid, a material-filled chamber, a gas-filled chamber, a fluid-filled chamber, or any other suitable barrier. In addition, the space 52 between the thermal barrier 50 and the tool 14 may be evacuated. Creating a vacuum aids in hindering heat transfer to the temperature management system 10 and the thermal component 12.
General Closing
The temperature management system 10 removes enough heat to maintain the thermal component 12 at or below its rated temperature, which may be; e.g., no more than 125° C. For example, the temperature management system 10 may maintain the component 12 at or below 100° C., or even at or below 80° C. Typically, the lower the temperature, the longer the life of the thermal component 12.
Thus, the temperature management system 10 may not manage the temperature of the entire cavity 15 or even the entire electronics chassis, but does manage the temperature of the thermal component 12 itself. When absorbing heat from the thermal component 12, the temperature management system 10 may allow the average temperature of the cavity 15 to reach a higher temperature than that at which the thermal components 12 are held. Absorbing heat from the thermal component 12 thus extends the useful life of the thermal component 12, despite the average temperature of the cavity 15 being higher. This allows the thermal component 12 to operate a longer duration at a given environment temperature for a given volume of heat sink than possible if the average temperature of the entire cavity 15 is managed.
Thermal Component, Heat Exchanger, and Heat Storing Temperature Management System
As with the temperature management system 10, the temperature management system 310 manages the temperature of a thermal component 312 mounted, e.g., on a board 318 in the downhole tool 14. The temperature management system 310 also comprises a heat exchanger 320 thermally coupled with the thermal component 312 as with the temperature management system 10. The temperature management system 310 also comprises a heat storing temperature management system 311 thermally coupled with the heat exchanger 320 as disclosed in the temperature management system 10, including similar reference numerals for like parts. The heat storing temperature management system 311 removes heat from the thermal component 312 through the heat exchanger 320 and stores the removed heat within the heat storing temperature management system 311. The heat storing temperature management system 311 also comprises a thermal conduit system 326 for thermally coupling the heat exchanger 320 and the heat sink 322.
Heat Exhausting Temperature Management System #2
The temperature management system 310 also comprises a heat exhausting temperature management system 340. However, in the temperature management system 310, the heat exhausting temperature management system 340 is thermally coupled with a second heat exchanger 321, which is thermally coupled to the thermal component 312 in a similar manner as the heat exchanger 320. Thus, instead of removing heat from the heat sink 322 of the heat storing temperature management system 311, the heat exhausting temperature management system 340 removes heat from the thermal component 312 through the second heat exchanger 321. The heat exhausting temperature management system 340 then transfers the removed heat to the environment outside the temperature management system 310. As before, the heat may be transferred to the drill string 16, the drilling fluid traveling in the annulus 52 between the downhole tool 14 and the formation 17, or the drilling fluid being pumped through the drill string 16 and the downhole tool 14. The heat may be transferred from the hot plate to the environment directly through conduction or indirectly through convection or radiation, or any combination of direct and indirect transfer. The heat exhausting temperature management system 340 allows removed heat to be transferred to the drilling fluid even though the drilling fluid may be at a higher temperature than the thermal component 312. The heat exhausting temperature management system 340 may also comprise more than one thermoelectric cooler thermally coupled with the thermal component 312, thus comprising multiple stages of heat exhausting temperature management. Instead of a thermoelectric cooler, alternatively the heat exhausting temperature management system 340 may comprise a thermoacoustic cooler or a vapor compression temperature management system. The temperature management system 310 may also be used to cool more than one thermal component 312.
Power for the thermal component 312 and the thermoelectric cooler 340, is similarly supplied by the turbine alternator 42, a battery, or combination thereof, which may be driven by the drilling fluid pumped through the drill string 16. Because the heat exhausting temperature management system 340 is powered by the turbine alternator 42, it may only operate during pumping of drilling fluid through the drill string 16. During that time, the heat exhausting temperature management system 340 removes heat from the thermal component 312 and allows the temperature management system 310 to maintain heat removal from the thermal component 312. There are, however, periods when drilling fluid is not pumped through the drill string 16. During these times, the heat exhausting temperature management system 340 may not be operational, unless there is some amount of battery power. However, when the heat exhausting temperature management system 340 is not operating, the heat storing temperature management system 311 is still able to remove heat from the thermal component 312 and store the removed heat the heat sink 322. Once drilling fluid flow is restored, the heat exhausting temperature management system 340 will then be able to begin removing heat from the thermal component 312. Thus, the heat storing temperature management system 311 and the heat exhausting temperature management system 340 combine to manage the temperature of the thermal component 312.
Alternatively, when the power source 36 is on, the heat exhausting temperature management system 340 may be operated by a control system that determines when the heat exhausting temperature management system 340 operates. The control system is similar to the control system described above and represented by the flow chart shown in
Thermal Barrier
The temperature management system 310 may also alternatively comprise a thermal barrier 350 enclosing the temperature management system 310. The thermal barrier 350 may also enclose only a portion of the temperature management system 310. The thermal barrier 350 hinders heat transfer from the outside environment to the temperature management system 310 and the thermal component 312.
General Closing
The temperature management system 310 removes enough heat to maintain the thermal component 312 at or below its rated temperature, which may be; e.g., no more than 125° C. For example, the temperature management system 310 may maintain the component 312 at or below 100° C., or even at or below 80° C. Typically, the lower the temperature, the longer the life of the thermal component 312.
Thus, the temperature management system 310 may not manage the temperature of the entire cavity 315 or even the entire electronics chassis, but does manage the temperature of the thermal component 312 itself. When absorbing heat from the thermal component 312, the temperature management system 310 may allow the average temperature of the cavity 315 to reach a higher temperature than that at which the thermal components 312 are held. Absorbing heat from the thermal components 312 thus extends the useful life of the thermal component 312, despite the average temperature of the cavity 315 being higher. This allows the thermal component 312 to operate a longer duration at a given environment temperature for a given volume of heat sink than possible if the average temperature of the entire cavity 315 is managed.
Thermal Component, Heat Exchanger, and Heat Storing Temperature Management System
As with the temperature management system 10, the temperature management system 410 manages the temperature of one or more thermal components 412 mounted on one or more boards 418 in the downhole tool 14. The temperature management system 410 also comprises a heat exchanger 420 thermally coupled with the thermal component 412 as with the temperature management system 10. The temperature management system 410 also comprises a heat storing temperature management system 411 thermally coupled with the heat exchanger 420 as disclosed in the temperature management system 10, including similar reference numerals for like parts. The heat storing temperature management system 411 removes heat from the thermal component 412 through the heat exchanger 420 and stores the removed heat in within the heat storing temperature management system 411. The heat storing temperature management system 411 also comprises a thermal conduit system 426 for thermally coupling the heat exchanger 420 and the heat sink 422.
Heat Exhausting Temperature Management System #3
The temperature management system 410 also comprises a heat exhausting temperature management system 440. However, in the temperature management system 410, the heat exhausting temperature management system 440 is thermally coupled with the heat exchanger 420, not the heat sink 422. Thus, instead of removing heat from the heat sink 422 of the heat storing temperature management system 411, the heat exhausting temperature management system 440 removes heat from the heat exchanger 420. The heat exhausting temperature management system 440 then transfers the removed heat to the environment outside the temperature management system 410. As before, the heat may be transferred to the drill string 16, the drilling fluid traveling in the annulus 52 between the downhole tool 14 and the formation 17, or the drilling fluid being pumped through the drill string 16 and the downhole tool 14. The heat may be transferred from the hot plate to the environment directly through conduction or indirectly through convection or radiation, or any combination of direct and indirect transfer. The heat exhausting temperature management system 440 allows removed heat to be transferred to the drilling fluid even though the drilling fluid may be at a higher temperature than the thermal component 412. The heat exhausting temperature management system 440 may also comprise more than one thermoelectric cooler thermally coupled with the thermal component 412, thus comprising multiple stages of heat exhausting temperature management. Instead of a thermoelectric cooler, alternatively the heat exhausting temperature management system 440 may comprise a thermoacoustic cooler or a vapor compression temperature management system. The temperature management system 410 may also be used to cool more than one thermal component 412.
Power for the thermal component 412 and the thermoelectric cooler 440 may be similarly supplied by the turbine alternator 42, which may be driven by the drilling fluid pumped through the drill string 16. If the heat exhausting temperature management system 440 is powered by the turbine alternator 42, it may only operate during pumping of drilling fluid through the drill string 16. During that time, the heat exhausting temperature management system 440 removes heat from the thermal component 412 through the heat exchanger 420 and allows the temperature management system 410 to maintain heat removal from the thermal component 412. There are, however, periods when drilling fluid is not pumped through the drill string 16. During these times, the heat exhausting temperature management system 440 may not be operational, unless there is some amount of battery power. However, when the heat exhausting temperature management system 440 is not operating, the heat storing temperature management system 411 is still able to remove heat from the thermal component 412 and store the removed heat the heat sink 422. Once drilling fluid flow is restored, the heat exhausting temperature management system 440 will then be able to begin removing heat from the thermal component 412. Thus, the heat storing temperature management system 411 and the heat exhausting temperature management system 440 combine to manage the temperature of the thermal component 412.
Alternatively, when the power source 36 is on, the heat exhausting temperature management system 440 may be operated by a control system that determines when the heat exhausting temperature management system 440 operates. The control system is similar to the control system described above and represented by the flow chart shown in
Thermal Barrier
The temperature management system 410 may also alternatively comprise a thermal barrier 450 enclosing the temperature management system 410. The thermal barrier 450 may also enclose only a portion of the temperature management system 410. The thermal barrier 450 hinders heat transfer from the outside environment to the temperature management system 410 and the thermal component 412.
General Closing
The temperature management system 410 removes enough heat to maintain the thermal component 412 at or below its rated temperature, which may be; e.g., no more than 125° C. For example, the temperature management system 410 may maintain the component 412 at or below 100° C., or even at or below 80° C. Typically, the lower the temperature, the longer the life of the thermal component 412.
Thus, the temperature management system 410 may not manage the temperature of the entire cavity 415 or even the entire electronics chassis, but does manage the temperature of the thermal component 412 itself. When absorbing heat from the thermal component 412, the temperature management system 410 may allow the average temperature of the cavity 415 to reach a higher temperature than that at which the thermal components 412 are held. Absorbing heat from the thermal component 412 thus extends the useful life of the thermal component 412, despite the average temperature of the cavity 415 being higher. This allows the thermal component 412 to operate a longer duration at a given environment temperature for a given volume of heat sink than possible if the average temperature of the entire cavity 415 is managed.
Thermal Component, Heat Exchanger, and Heat Storing Temperature Management System
As with the temperature management system 10, the temperature management system 510 manages the temperature of one or more thermal components 512 mounted on one or more boards 518 in the downhole tool 14. The temperature management system 510 also comprises a heat exchanger 520 thermally coupled with the thermal component 512 as with the temperature management system 10. The temperature management system 510 also comprises a heat storing temperature management system 511 thermally coupled with the heat exchanger 520 as disclosed in the temperature management system 10, including similar reference numerals for like parts. The heat storing temperature management system 511 removes heat from the thermal component 512 through the heat exchanger 520 and stores the removed heat in within the heat storing temperature management system 511. The heat storing temperature management system 511 also comprises a thermal conduit system 526 for thermally coupling the heat exchanger 520 and the heat sink 522.
Heat Exhausting Temperature Management System #4
The temperature management system 510 also comprises a heat exhausting temperature management system 540. However, in the temperature management system 510, the heat exhausting temperature management system 540 is thermally coupled with the thermal conduit system 526, not the heat sink 522. Thus, instead of removing heat from the heat sink 522 of the heat storing temperature management system 511, the heat exhausting temperature management system 540 removes heat from the thermal conduit 526. The heat exhausting temperature management system 540 then transfers the removed heat to the environment outside the temperature management system 510. As before, the heat may be transferred to the drill string 16, the drilling fluid traveling in the annulus 52 between the downhole tool 14 and the formation 17, or the drilling fluid being pumped through the drill string 16 and the downhole tool 14. The heat may be transferred from the hot plate to the environment directly through conduction or indirectly through convection or radiation, or any combination of direct and indirect transfer. The heat exhausting temperature management system 540 allows removed heat to be transferred to the drilling fluid even though the drilling fluid may be at a higher temperature than the thermal component 512. The heat exhausting temperature management system 540 may also comprise more than one thermoelectric cooler thermally coupled with the thermal component 512, thus comprising multiple stages of heat exhausting temperature management. Instead of a thermoelectric cooler, alternatively the heat exhausting temperature management system 540 may comprise a thermoacoustic cooler or a vapor compression temperature management system. The temperature management system 510 may also be used to cool more than one thermal component 512.
Power for the thermal component 512 and the thermoelectric cooler 540, may similarly be supplied by the turbine alternator 42, which may be driven by the drilling fluid pumped through the drill string 16. Because the heat exhausting temperature management system 540 is powered by the turbine alternator 42, it may only operate during pumping of drilling fluid through the drill string 16. During that time, the heat exhausting temperature management system 540 removes heat from the thermal component 512 through the thermal conduit 526 and allows the temperature management system 510 to maintain heat removal from the thermal component 512. There are, however, periods when drilling fluid is not pumped through the drill string 16. During these times, the heat exhausting temperature management system 540 may not be operational, unless there is some amount of battery power. However, when the heat exhausting temperature management system 540 is not operating, the heat storing temperature management system 511 is still able to remove heat from the thermal component 512 and store the removed heat the heat sink 522. Once drilling fluid flow is restored, the heat exhausting temperature management system 540 will then be able to begin removing heat from the thermal component 512. Thus, the heat storing temperature management system 511 and the heat exhausting temperature management system 540 combine to manage the temperature of the thermal component 512.
Alternatively, when the power source 36 is on, the heat exhausting temperature management system 540 may be operated by a control system that determines when the heat exhausting temperature management system 540 operates. The control system is similar to the control system described above and represented by the flow chart shown in
Thermal Barrier
The temperature management system 510 may also alternatively comprise a thermal barrier 550 enclosing the temperature management system 510. The thermal barrier 550 may also enclose only a portion of the temperature management system 510. The thermal barrier 550 hinders heat transfer from the outside environment to the temperature management system 510 and the thermal component 512.
General Closing
The temperature management system 510 removes enough heat to maintain the thermal component 512 at or below its rated temperature, which may be; e.g., no more than 125° C. For example, the temperature management system 510 may maintain the component 512 at or below 100° C., or even at or below 80° C. Typically, the lower the temperature, the longer the life of the thermal component 512.
Thus, the temperature management system 510 may not manage the temperature of the entire cavity 515 or even the entire electronics chassis, but does manage the temperature of the thermal component 512 itself. When absorbing heat from the thermal component 512, the temperature management system 510 may allow the average temperature of the cavity 515 to reach a higher temperature than that at which the thermal components 512 are held. Absorbing heat from the thermal component 512 thus extends the useful life of the thermal component 512, despite the average temperature of the cavity 515 being higher. This allows the thermal component 512 to operate a longer duration at a given environment temperature for a given volume of heat sink than possible if the average temperature of the entire cavity 515 is managed.
While specific embodiments have been shown and described, modifications can be made by one skilled in the art without departing from the spirit or teaching of this invention. The embodiments as described are exemplary only and are not limiting. Many variations and modifications are possible and are within the scope of the invention. Accordingly, the scope of protection is not limited to the embodiments described, but is only limited by the claims that follow, the scope of which shall include all equivalents of the subject matter of the claims.
