1. Field of the Disclosure
The present disclosure relates to regulating temperature of devices in a tool operating in a wellbore.
2. Description of the Related Art
Measurement-while-drilling operations generally employ a drilling tool that includes various sensors, processors and devices operating downhole in order to enable drilling operations. Typical downhole devices are composed of a multitude of printed circuit boards and individual components like sensors and integrated circuits. The lifetime of these electrical components depends on various factors including their operating temperature, their temperature specification, and temperature stability (low temperature variations have an important impact). As drilling takes place at increasingly greater depths and hence higher temperatures, there is a growing demand for downhole devices that operate at high temperatures.
The particular circumstances involved in operating devices in a measurement-while-drilling tool provide further difficulties with respect to heat generation. Due to a generally small installation space in the tool and the increasing level of heat generation, these extreme heat quantities over a small volume can be created and lead to overheating. The need for power dissipation therefore increases significantly. Using a temperature control system for an electrical device can significantly enhance the lifetime of the component. Therefore, there is a need to regulate the temperature of devices operating in a tool in a wellbore environment.
In one aspect, the disclosure provides an apparatus that includes a heat source, a channel associated with the heat source and a device configured to flow a carrier through the channel that absorbs heat from the heat source.
In another aspect, the disclosure provides an apparatus for use in a downhole tool, including a substrate; a heat source associated with the substrate, the heat source inducing heat into the substrate; a fluid channel in the substrate; and a fluid flow unit configured to flow a fluid through the fluid channel to regulate a temperature of the component.
In another aspect, the present disclosure provides a method for regulating a temperature of a device in a tool in a wellbore, including providing the device having a substrate having a fluid channel therein in the wellbore; inducing heat from a heat source into the substrate; and flowing a fluid through the fluid channel to regulate the temperature of the device.
The present disclosure is best understood with reference to the following figures in which like numerals generally refer to like elements and in which:
During typical drilling operations, a suitable drilling fluid 131 (also referred to sometimes as “mud” or “drilling mud”) from a mud pit (source) 132 may be circulated under pressure through a channel in the drill string 120 by a mud pump 134. The drilling fluid 131 may pass from the mud pump 134 into the drill string 120 via a desurger (not shown), a fluid line 138, and the Kelly joint 121. The drilling fluid 131 is generally discharged downhole at a wellbore bottom 151 through an opening (not shown) in the drill bit 150 and circulates uphole through an annular space 127 between the drill string 120 and the wellbore 126, returning to the mud pit 132 via a return line 135. The drilling fluid 131 lubricates the drill bit 150 and carries wellbore 126 cuttings and/or chips away from the drill bit 150. A flow rate sensor or dynamic pressure sensor S1 is typically placed in the fluid line 138 and may provide information about the drilling fluid 131 flow rate and/or dynamic pressure. A surface torque sensor S2 and a surface rotational speed sensor S3 associated with the drill string 120 may provide information about the torque and the rotational speed of the drill string 120, respectively. Additional sensors (not shown) may be associated with the line 129 to provide the hook load of the drill string 120.
In one aspect, the drill bit 150 may be rotated by only rotating the drill pipe 122. In another aspect, a downhole motor 155 (mud motor) may be disposed in the BHA 190 to rotate the drill bit 150. The drill pipe 122 may be rotated to supplement the rotational power of the mud motor 155 or to effect changes in the drilling direction. The mud motor 155 may be coupled to the drill bit 150 via a drive shaft (not shown) disposed in a bearing assembly 157. The mud motor 155 may rotate the drill bit 150 when the drilling fluid 131 passes through the mud motor 155 under pressure. The bearing assembly 157 may support the radial and/or the axial forces of the drill bit 150. A stabilizer 158 coupled to the bearing assembly 157 may act as a centralizer for the lowermost portion of the mud motor 155 and/or the BHA 190.
In one aspect, a drilling sensor module 159 placed near the drill bit 150 may contain sensors, circuitry, and/or processing software to determine dynamic drilling parameters, such as bit bounce of the drill bit 150, stick-slip of the BHA 190, backward rotation, torque, shocks, borehole pressure, annulus pressure, acceleration measurements, etc. A suitable telemetry and/or communication sub 172 may also be provided to communicate data to and from the surface. The drilling sensor module 159 may process the raw sensor information and/or may transmit the sensor information to a surface control 140 via the telemetry system 172 or a transducer 143 coupled to the fluid line 138, as shown at 145.
The communication sub 172, the power unit 178, and a formation evaluation (FE) tool 179 may all be connected in tandem with the drill string 120. Flex subs, for example, may be used in connecting the FE tool 179 to the BHA 190. The BHA 190 may perform various measurements, such as pulsed nuclear magnetic resonance (NMR) measurements and/or nuclear density (ND) measurements, for example, while the borehole 126 is being drilled. The BHA 190 may include one or more formation evaluation and/or other tools and/or sensors 177, such as a temperature sensor 177a, capable of making measurements of the downhole mud (drilling fluid) 131 temperature over time and arranged to do so, and/or a mud (drilling fluid) 131 dynamic pressure and/or flow rate sensor 177b, capable of making measurements of the downhole mud (drilling fluid) 131 dynamic pressure and/or flow rate. These various measurement devices may employ, for example, a microprocessor, a multi-layered circuit board or any other electrical components that generate excess heat during their operation. In another aspect, the devices or electrical components may be heated due to exposure to the temperature of the surrounding environment. Such heat-generating devices and/or heated devices may be provided with heat carrier channels proximate to them that provide a circulating heat carrier into and away from the device for removing heat. In one aspect, a heat-generating device or heated device may have a channel integrated therein to provide flow of the heat carrier within the device and to bring the heat carrier into thermal contact with the heat-generating portion (or heated portion) of the device. In another aspect, the heat carrier channel may be provided on one side of the device or may be wrapped around the device.
The communication sub 172 typically obtains the measurements from the various sensors and transfers the signals, to be processed at the surface. Alternatively, the signals may be processed downhole, using a downhole processor 177c in BHA. The communication between the surface and the downhole devices may be established using any suitable telemetry technique, including, but not limited to, mud pulse telemetry, electro-magnetic telemetry, acoustic telemetry, and wired pipe. The wired pipe may be: a coiled tubing, in which the tubing caries a communication link; or jointed tubulars, wherein the individual tubulars carry a communication link, such as an electrical conductor or an optical fiber.
The surface control unit 140 receives and processes signals from one or more other downhole sensors as well as the flow rate sensor S1, the surface torque sensor S2, and/or the surface rotational speed sensor S3 and other sensors used in the drilling system 100. The surface control unit 140 may display desired drilling parameters on a display 142 that may be utilized by an operator to control the drilling operations. The surface control unit 140 may typically include a computer or processor, at least one memory for storing programs and data, and a recorder for recording data. The surface control unit 140 may typically be configured to activate one or more alarms 144 under certain operating conditions.
The present disclosure provides a temperature control system for controlling temperature of one or more components in the BHA 190 or another apparatus, such as a wireline tools used for logging wellbores. The temperature control system, in general, pumps a heat carrier through a channel or a channel system made proximate to or integrated or embedded in a housing or body of the one or more components in the BHA 190. Such components may include, but are not limited to, electrical components (such as microprocessors, etc.), sensors or devices having multiple layers, such as multilayer circuit boards or substrates. The one or more components may be heat-generating components, components heated by the downhole environment, or other components that may benefit from rapid heat dissipation therefrom. The heat carrier flows through the channel system and carries heat to or away from the component in order to regulate (raise or lower) the temperature of the component. The geometry of the heat carrier channels and their proximity to the heat sources allows not only controlling of the temperature of the components but also allows removing of various hot spots. Although
The heat carrier 225 is a medium that is able to absorb or resorb thermal energy. The heat carrier may be in a gaseous, liquid or solid state or in any combination of these states. The thermal energy is stored in the heat carrier by temperature changes of the heat carrier, in chemical transformations or phase changes of the heat carrier or by any combination of these processes. The heat carrier 225 may be selected according to various selection criteria, such as the desired operating temperature of the heat-generating device 230 as well as the heat capacity, movability, viscosity and durability of the heat carrier 225. In an aspect in which the heat carrier 225 is a fluid, the fluid may be selected to have a boiling point that allows heat storage using the latent heat of the phase transition from liquid to gaseous. In another aspect in which the heat carrier is solid, the solid material may be selected to have a melting point that allows heat storage using the latent heat of the phase transition from solid to liquid.
In one aspect, the one or more heat carrier transfer devices 220a-c includes a thermal conduit system 224 for moving the heat carrier throughout the temperature control apparatus 200. The thermal conduit system 224 may include tubes, hoses or other encapsulation devices that have an entrance and an exit and encapsulate the heat carrier. The geometry and material of the heat carrier transfer device may be selected depending on the application, amount of dissipated heat and desired temperature gradient. In one embodiment, the thermal conduit system 224 is arranged to provide a closed-loop system in which the heat carrier 225 moves from the heat carrier storage unit 210 to a channel of the heat-generating device 230 and then to the heat sink device 240 and back to the heat carrier storage unit 210. In another embodiment, the thermal conduit system is arranged provide an open loop system in which the heat carrier 225 moves from the heat carrier storage unit 210 to a channel of the heat-generating device 230 and then to the heat sink device 240. An exemplary open loop system may include heat carrier transfer devices 220a and 220b but not the heat carrier transfer device 220c which otherwise returns the heat carrier 225 from the heat sink 240 to the heat carrier storage unit 210. Although the exemplary temperature control apparatus 200 has been described with respect to three heat carrier transfer devices 220a-c, this is not meant to be a limitation of the disclosure. Any number of heat carrier transfer devices may be used within the scope of the disclosure.
In one aspect, at least one of the heat carrier transfer devices, such as heat carrier transfer device 220a, includes a pump 222 for circulating the heat carrier 225 throughout the temperature control apparatus 200. The pump 222 may be selected according to various criteria, such as flow rate, pressure difference, operating temperature, power consumption, size, weight and durability under downhole conditions. In an alternate embodiment, a passive device, such as a heat pipe, may be used in place of the pump 222.
In one embodiment, the heat-generating device 230 includes a multi-layer circuit board 242 or individual electronic components or sensors having a multilayer structure. The exemplary multi-layer circuit board 242 includes at least one printed circuit board 232, one or more insulating layers 234, a cooling layer 236 and a carrier layer 237. In the exemplary multi-layer circuit board 242 of
The heat sink 240 absorbs or resorbs heat from the heat carrier 225 and dissipates it to a heat carrier storage unit 210. In one embodiment, heat is passively conducted to the environment, such as the drilling mud passing through the downhole tool. In another embodiment a heat pump actively transfers heat from the heat carrier 225 to the surrounding environment. The heat pump may move heat from the heat carrier 225 to the environment using mechanical work, where the source has a higher temperature than the environment. This provides an efficient transfer of heat since the temperature of the hot side of the heat pump is higher than the temperature of the environment and further since the environment has a much greater heat capacity. Such a system allows a rapid transfer of heat and brings the hot side of the heat pump close to thermal equilibrium with the environment, thereby lowering its temperature. In another embodiment the heat energy may be stored in a chemical transformation or a phase change reaction.
A sensor 245 may be disposed at or proximate the heat-generating device 230 in order to regulate operation of the temperature control apparatus 200. The sensor 245 may be configured to provide a suitable measurement to a controller 228. In one aspect, the measurement is a temperature measurement. The controller 228 may be responsive to a specific temperature of the heat-generating device and be configured to maintain the heat-generating device within a specified temperature range. Alternatively, the controller 228 may be responsive to a temperature gradient between the heat-generating device 230 and the surrounding environment and may be configured to maintain the temperature gradient between the heat-generating device and the environment within a specified range. In one aspect, the controller 228 may affect an operation of the pump 222 to provide faster or slower circulation of the heat carrier 225 through channel 238a. In another aspect, the controller 228 may affect operation of the heat sink 240 (i.e., the heat pump) to decrease or increase a rate at which heat is removed from the heat carrier 225 to the surrounding environment. The controller may also control the temperature of the heat sink (e.g. the temperature of the “cold” side of the heat pump). It is noted that although the sensor is described herein as providing a temperature measurement, in other aspects, the sensor may be configured to provide other measurements, such as a flow rate of the heat carrier through the channel system 238.
Although the disclosure includes a method and apparatus for regulating a temperature of a heat-generating device such as a multi-layer circuit board using for drilling purposes, the method and apparatus may also be used to regulate the temperature of devices used for other purposes such as monitoring purposes, activation purposes, and downhole activities not directly related to drilling a wellbore. Such devices may include temperature sensors, pressure sensors, hydraulic valves and other electronic components. In an alternate embodiment, the temperature control apparatus may be used to provide heat to batteries that are designed for operation at high temperatures or in a specific temperature range. In yet another alternate embodiment, the temperature control apparatus may be used to melt salt, which may be used as a buffer for storing heat and work.
In another aspect, the temperature control apparatus may be operated to adjust or alter a temperature of the exemplary heat-generating device to operate at a desired temperature range, such as an optimal operation temperature, thereby avoiding temperature ranges in which the device works with low reliability. It is also noted that mechanical fatigue or the break down of components is often caused by temperature cycling or thermal-induced stresses. Shocks of extreme temperature changes of up to 200 K have been noted in geothermal applications, such as in the start of production of hot fluid, the start of pumping to drill, etc. Thus, in one aspect, the disclosed temperature control apparatus may be used to reduce mechanical fatigue and maintain a mechanical strength of a component by reducing the impact of thermal stresses on the component.
Thus, in one aspect, the disclosure provides an apparatus that includes a heat source or a device whose temperature is desired to be regulated, a channel associated with the heat source and a flow device or a flow unit configured to flow a carrier through the channel, which carrier absorbs heat from the heat source.
In another aspect, the apparatus further includes a medium associated with the carrier configured to absorb heat from the carrier. The medium may be any suitable medium that is configured to absorb heat from the heated carrier, including, but not limited to, a heat sink, a device in thermal communication with the carrier that is at a temperature below the temperature of the carrier, and a fluid (such a drilling fluid) in thermal communication with the carrier that is at a temperature below the temperature of the carrier. In yet another aspect, the disclosure provides an apparatus for use in a downhole tool, including a substrate; a heat source associated with the substrate, the heat source inducing heat into the substrate; a fluid channel in the substrate; and a fluid flow unit configured to flow a fluid through the fluid channel to regulate a temperature of the component. The fluid flow unit may include a pump configured to supply the fluid from a storage unit to the channel. A heat sink receives fluid from the substrate. The heat sink may include a thermally conductive element configured to conduct heat from the fluid received from the substrate to a fluid flowing through the tool when the tool is in the wellbore. The apparatus may further include a conduit system configured to provide the fluid into the fluid channel and out of the fluid channel. The conduit system may provide an open loop path for the fluid or a closed loop path for the fluid. The heat source may be at least one of: (i) a component generating heat when the component is in operation; and (ii) an environment surrounding the substrate. A controller of the apparatus regulates the temperature of the component by controlling an operation of one at least one of: (i) a heat sink dissipating heat from the fluid, (ii) a heat sink dissipating heat into the fluid; and (iii) a pump circulating the fluid through the fluid channel. A sensor coupled to the substrate may provide a temperature measurement of the substrate to the controller to regulate the temperature of the component. A flow rate sensor configured measure a flow rate of the fluid through the fluid channel and provides the flow rate measurement to the controller to regulate the temperature of the component.
In another aspect, the present disclosure provides a method for regulating a temperature of a device in a tool in a wellbore, including providing the device having a substrate having a fluid channel therein in the wellbore; inducing heat from a heat source into the substrate; and flowing a fluid through the fluid channel to regulate the temperature of the device. The fluid may be provide to the substrate from a fluid storage unit and received from the substrate at a heat sink. In one embodiment, the heat sink comprises a thermally conductive element and the method further includes conducting heat from the fluid received from the substrate to a fluid flowing through the tool. A conduit system provides the fluid into the fluid channel and out of the fluid channel. The conduit system may provide one of: (i) an open loop path for the fluid; and (ii) a closed loop path for the fluid. In various embodiments, the heat source is at least one of: (i) a component associated with the substrate generating heat when the component is in operation; and (ii) an environment surrounding the substrate. The temperature of the component may be regulated by using a controller to control an operation of one at least one of: (i) a heat sink dissipating heat from the fluid, (ii) a heat sink dissipating heat into the fluid, and (iii) a pump circulating the fluid through the fluid channel. A temperature measurement of the substrate may be provided to the controller from a sensor coupled to the substrate to regulate the temperature of the component. Additionally, a flow rate of the fluid through the fluid channel may be provided to the controller to regulate the temperature of the component.
The embodiments described herein, therefore, are well adapted to carry out the invention. While various embodiments of the invention have been described for purposes of this disclosure, numerous changes known to persons of skill in the art may be made to practice the invention and to accomplish the results contemplated herein, without departing from the concept or the spirit of the invention. Various modifications will be apparent to those skilled in the art. It is intended that all such variations that are within the scope of the appended claims be embraced by the foregoing disclosure.
This application claims priority to U.S. Provisional Application Ser. No. 61/356,434, filed Jun. 18, 2010.
Number | Date | Country | |
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61356434 | Jun 2010 | US |