DE102004053251A1 - A downhole tool cooling apparatus and method of cooling a component disposed in a downhole tool - Google Patents

Abstract

A downhole tool cooling apparatus (20) having an insulating chamber (24) disposed in the downhole tool (20) adapted to receive an object (47) to be cooled and a Stirling cooler (22) disposed in the downhole tool (20) a cold end configured to remove heat from the insulating chamber (24) and a hot end adapted to dissipate heat.

Description

The The invention relates to a cooling device for a Downhole tool and method for cooling a downhole tool arranged component according to the preamble of claim 1 or 8th.

On the field of hydrocarbon and water exploration and production are various well logging and monitoring techniques known. Drilling hole tools or instruments are used which are provided with sources for sending energy through a borehole is formed, which is an underground formation crosses. The radiated energy passes through the borehole fluid ("Mud") and get in the surrounding formations, which generates signals that be detected and measured by one or more sensors, the typically also disposed on the downhole tools. By processing the detected Signal data is obtained a profile of the formation properties.

One Borehole tool with multiple energy emitting sources and sensors To measure various parameters can be at the end of a cable, a Wireline, a drill string or the like. lowered into a borehole become. The cable or the wireline is with a mobile processing center at the earth's surface and provides the means by which data is sent up to the surface become. With this kind of data acquisition over a wireline is it possible to drill and to measure formation parameters as a function of depth, i. while that Drill hole tool is pulled uphole in the borehole.

As an alternative to wireline borehole data acquisition techniques, it is known to collect data on downhole conditions during the drilling process. By collecting and processing such information during the drilling process, the drill operator may alter or correct drilling steps to optimize performance. Techniques for collecting data on downhole conditions and moving the drilling assembly during the drilling operation are known as measurement-while-drilling (MWD) techniques. Similar techniques, where the emphasis is more on the measurement of formation parameters than on the movement of the drilling assembly, are known as data-tray-while-drilling (LWD) techniques. Data Logging While Tripping (LWT) is an alternative to the LWD and MWD techniques. In the LWT technique, a small diameter insertion tool at the end of a drilling pass just before the drill pipe is withdrawn is lowered through the drill pipe downhole. The insertion tool is used to measure downhole physical values as the drill string is being withdrawn or withdrawn from the wellbore. Measured data is stored in memory in the insertion tool as a function of time during retraction. At the surface, a second set of equipment stores the depth as a function of the time to move out, allowing the measurements to be assigned to the depth. 1 shows a conventional data collection tool 12 that in a borehole 11 is arranged, which is an underground formation 10 crosses. The data collection tool 12 can on a wireline 13 via a wireline control mechanism 14 be introduced. In addition, the data collection tool 12 with a device 15 be connected to the earth's surface, which may include a computer.

Downhole tools are extreme temperatures (up to 260 ° C) and pressures (up to 30,000 psi, respectively about 200 MPa, and in some cases up to 40,000 psi, corresponding to about 275 MPa). These tools are common with sensitive components, such as electronic devices, equipped, often not for such low environments are designed. At the manufacturers of electronic Components dominate the trend, the high-volume commercial Market to use, which makes it difficult to drill hole components to find that increased among these Temperatures reliable work. At the same time, the oil industry is tending to seek deeper and hotter Reservoirs. Therefore, there is a need for methods or devices which make it possible the sensitive electronic components at high temperatures to operate. The redesign of silicon chips to help with this high temperatures (for example, above 150 ° C) work, is costly and has a significant impact on development time and hence the time it takes to get the product up the market is coming. The alternative to this are devices that the electronic components against the high temperatures protect. Conventional techniques include those that are sensitive Components opposite the hot ones Isolate environment, for example, by placing them in Dewar vessels become. This technique protects the tool only for a certain period of time, and the type of vessels leads to a significant risk of breakage. A better approach is to use an active cooling device.

A cooling device capable of providing several watts of cooling for heat-protected electronic components in downhole tools would enable the use of electronic and sensor technologies that would otherwise be unsuitable for high temperature applications. This would also reduce the ever-increasing costs of developing and implementing high-temperature electronics. Finally, such a cooling device would make it possible to introduce new techniques of underground exploration and production.

A cooler for use in a borehole must be in the limited space in the downhole tool. Various miniature cooling devices, the for the use in well tools are known. For example, beats Aaron Flores, "Active Cooling for Elektronis in a Wireline Oil Exploration Tool ", Dissertation, MIT, 1996, a technique based on a unique vapor compression cycle based. However, this approach requires very careful sealing and Lubrication due to high pressures in the condenser.

Out Gloria Bennett "Active Cooling for Downhole Instrumentation: Miniature Thermoacoustic Refrigerator ", Dissertation, University of New Mexico, 1991, UMI 1991.9215048, is an active cooling device for borehole tools known on a thermoacoustic miniature refrigerator based. Although this approach is promising, the ones used are Components relatively bulky and the capacity of a thermoacoustic miniature refrigerator is uncertain.

Of the Invention is therefore the object of a cooling device for a A downhole tool and a method of cooling a tool in a downhole tool arranged component according to the preamble of claim 1 or 8 create, with which an improved cooling is possible.

These Task is according to the features of claims 1 and 8 solved.

hereby will be an improved cooling for borehole tools created. The cooling device is able to drill downhole components at significantly lower temperatures to hold so that this Components an increased Efficiency and an extended one Have life. The cooling device comprises a closed system with a minimum number of moving ones Parts, creating a more uniform, bumplessly and quiet operation allows which is advantageous in terms of the selection requirements On impact- and vibration resistance of the drill hole tool to be attached Instruments.

Further Embodiments of the invention are the following description and the dependent claims refer to.

The The invention is described below with reference to the attached figures illustrated embodiments explained in more detail.

1 shows a known downhole tool in a borehole.

2 shows a downhole tool with a Stirling cooler.

3 illustrates the heat transfer with a Stirling cooler.

4 shows a free-piston Stirling cooler.

5 illustrates the Stirling cycle.

6 illustrates different states of the pistons in the Stirling cooler in a Stirling cycle.

7 schematically shows an active cooling device with an air flow.

8th schematically shows a cooling device with a liquid.

9 illustrates a method of making a downhole tool.

10 illustrates a method for cooling sensors, electronics or the like. in a downhole tool.

embodiments The invention relates to cooling devices for use in downhole tools. These cooling devices are based on Stirling cycles, who can work efficiently in a closed system, no Need lubrication and at relatively lower To press work in comparison to vapor compression devices. A Stirling engine or cooler based on the well-known thermodynamic Stirling cycle. A Stirling engine uses heat (temperature difference) as the energy source to to provide a mechanical work. A Stirling cooler works opposite: he uses mechanical energy to get a temperature difference to create, for example, as a cooler or freezer.

Various configurations of Stirling engines / coolers are known. These can be classified into kinematic and free-piston types the. Kinematic Stirling engines use pistons coupled to drive mechanisms to translate linear piston motions into rotational motions. Kinematic Stirling engines may also be classified as alpha type (two pistons), beta type (piston and displacer in one cylinder), and gamma type (pistons and displacer in separate cylinders). Free-piston Stirling engines use harmonic motion mechanics that can use even springs or magnetic field vibrations to provide harmonic motion.

Due to significant technical requirements, Stirling engines are rarely used in practice, and the use of Stirling coolers is limited to the specialty of cryogenics and military applications. The development of Stirling engines / coolers includes practical considerations such as efficiency, vibration, life and cost. The use of Stirling engines / coolers on downhole tools results from the limited space available in a downhole tool (typically about 7.5 to about 15 cm in diameter) and the adverse environment in the borehole (e.g., temperatures up to 260 ° C, pressures to to 30,000 psi, corresponding to about 200 MPa or more, and jarring up to 250 g or more) additional difficulties. Stirling engines have been proposed for use as electric generators for downhole tools, cf. US 4,805,407 ,

embodiments of the present invention use any Stirling cooler. Some embodiments use free piston Stirling cooler. A embodiment a free-piston Stirling cooler uses a linear motor with a moving magnet.

2 shows a borehole tool according to the invention 20 according to the downhole tool 12 of the 1 , The illustrated downhole tool 20 includes an elongated housing 21 which different components 23 protects. The components 23 may include electronic devices that must be protected from high temperatures. The components 23 are in an insulating surround or chamber 24 arranged and with a Stirling cooler 22 connected. At the other end of the Stirling cooler 22 can have more components 25 of the downhole tool 20 be provided. The components 25 Other electronic devices can be used to control the Stirling cooler 22 or mechanisms for removing heat from the hot end of the Stirling cooler 22 include.

3 schematically illustrates the heat removal according to the invention using a Stirling cooler. A Stirling cooler 22 works as a heat pump, taking heat from a cold reservoir 33 to the mud flow (heat reservoir) 31 derives. In this way, the object to be cooled (cold reservoir 33 ) effectively removes heat to the other end, the hot end, of the Stirling cooler 22 "Pumped" and for example in the mud flow 31 derived. The Stirling cooler 22 can be in direct contact with the object to be cooled. Alternatively, the Stirling cooler 22 spaced from the object to be cooled, wherein a heat transfer mechanism 35 between the two is provided to transfer heat. The heat transfer mechanism 35 may be any suitable heat transfer device, such as a heat pipe, including those that operate with circulating liquids. Embodiments of the invention may be implemented with cold and / or hot side heat transfer mechanisms.

4 illustrates a free-piston Stirling cooler for use in embodiments of the invention. The illustrated Stirling radiator 40 is on an object to be cooled 47 attached. To transfer heat between the object 47 and the Stirling cooler 40 may be provided as described above, a heat transfer device. The Stirling cooler 40 includes two pistons 42 . 44 in a cylinder 46 are arranged. The cylinder 46 is filled with a working gas, typically air, helium or hydrogen, at a pressure which reaches a multiple, say 20 times, the atmospheric pressure. The piston 42 is to a permanent magnet 45 coupled, which is adjacent to an electromagnet 48 is arranged, which is fixed to the housing. Will the electromagnet 48 energized, its magnetic field interacts with that of the permanent magnet 45 to a linear movement of the piston 42 to cause in the figure to the right and to the left. The permanent magnet 45 and the electromagnet 48 thus form a linear motor with a movable magnet. The concrete dimensions and forms of in 4 shown magnets are for illustration only. The places of the electromagnet 48 and the permanent magnet 45 can also be reversed, ie the electromagnet 48 can on the piston 42 be attached while the permanent magnet 45 attached to the housing.

The electromagnet 48 and the permanent magnet 45 may be formed of any suitable material. The turns and layers of the electromagnet 48 are preferably chosen so that it can withstand a high temperature, for example up to 260 ° C. The permanent magnet 45 may be formed of a samarium-cobalt (Sm-Co) alloy to provide high performance at high temperatures. The for operation of the electromagnet 48 required electricity may be supplied from the surface of the earth or from conventional downhole tool batteries, downhole generators, or any other means.

The movement of the piston 42 causes a change in the gas volume of the cylinder 46 , The cylinder 44 is in the cylinder 46 as a displacer in Stirling engines of the kinematic type movable. The movement of the piston 44 is caused by a pressure difference between both sides of the piston 44 triggered. The pressure difference comes from the movement of the piston 42 , The movement of the piston 44 in the cylinder 46 Moves the working gas from the left side of the piston 44 on the right side of the piston 44 , and vice versa. This movement of the gas, coupled with the compression and decompression processes, results in heat transfer from the object 47 to the heat dissipation device 43 , This reduces the temperature of the object 47 , The Stirling cooler 40 can be a feather mass 41 include to reduce vibrations that originate from the movements of the piston and the magnetic motor.

Even though 4 shows a Stirling cooler with a magnetic motor that requires electricity to drive the Stirling engine, other sources of energy or drive mechanisms may be used. For example, the operation of the Stirling radiator (eg, the forward and reverse movements of the piston 42 in 4 ) may be implemented by mechanical means, such as a liquid powered system that utilizes the energy of the mud flow and is coupled to a valve system and / or a spring. The hydraulic pressure of the mud flow can also be used to push the piston in one direction while the spring is used to push the piston in the other direction. A conventional valving system may be used to intermittently control the mud flow to the piston. The coordinated action of a hydraulic system, a spring and a valve system thus results in a forward and backward movement of the piston 42 ,

The movement of the gas on the right and the left side of the piston 44 , coupled with the compression and decompression of the gas in the cylinder 46 through the piston 42 , leads to four different states in a Stirling cycle. 5 represents these four states as well as the transitions between these states in a pressure-volume diagram. 6 illustrates the four states and the direction of the movements of the pistons 42 and 44 in a Stirling cycle.

In a process a from a state 1 to a state 2 the piston moves 44 in 6 from left to right, while the piston 42 fixed. Therefore, the volume remains in the cylinder 46 , please refer 4 , unchanged. The working gas in the cylinder 46 moves from one side of the piston 44 on the other side.

In a second process b from the state 2 to a state 3 the piston moves 42 to the right, whereby the volume in the cylinder, cf. cylinder 46 in 4 , is increased. The magnet motor drives the movement of the piston 42 at. Due to the increased volume in the cylinder, the gas expands and absorbs heat.

In a process c from the state 3 to a state 4 the piston moves 44 to the left and forces a movement of the working gas on its right side. The volume of the gas remains unchanged.

In a process d from the state 4 back to the state 1 the piston moves 42 under drive by the magnet motor to the left. As a result, the working gas is compressed. The compression results in a release of heat from the working gas. The released heat is passed through the heat dissipation device 43 to a heat sink or to the environment, such as the drilling mud, derived. This completes the Stirling cycle. The net result is the transfer of heat from one end of the device to the other. Thus, when the Stirling radiator is in thermal or thermal contact with the object to be cooled, either directly or through a heat transport mechanism (Object 47 in 4 ), heat can be removed from the object. As a result, the temperature of the object can be reduced or heat generated on the object can be removed.

7 schematically shows an embodiment of a cooling device with a Stirling cooler. The illustrated Stirling radiator 22 is here with an insulating surround or chamber 24 coupled. In the chamber 24 is an interior 26 for providing a path for air flow over one or more components 23 in the chamber 24 are arranged. The interior 26 can be formed using any known conventional material. A fan 27 is in the chamber 24 arranged to air around the components or objects to be cooled 23 to circulate, thereby actively removing heat from the components 23 dissipates, on the cold side of the Stirling cooler 22 is transmitted. The ventilator 27 can by the electrical power supply, which also includes the Stirling cooler 22 drives, or by an independent power supply, such as a separate battery operated. The illustrated embodiment further comprises a heat exchanger 28 on, at one end of the chamber 24 is arranged to increase the cooling efficiency via the cooler / chamber interface and to cool the circulating air. The heat exchanger 28 may be a conventional heat sink or other suitable device. In further embodiments, multiple fans 27 be provided to increase the cooling air flow.

8th shows a further embodiment of a cooling device with a Stirling cooler. The illustrated Stirling radiator 22 is with an insulating surround or chamber 24 coupled. In the chamber 24 is an inner liquid-based cooling system 29 arranged. The cooling system 29 has a flow loop that allows a liquid to flow in a closed loop of objects or components 23 to a heat exchanger 28 to flow on the cold side of the Stirling radiator 22 is attached. The cooling system 29 may be formed using known materials, for example a plurality of tubes. The heat exchanger 28 may be an ordinary heat sink or other suitable device. The cooling liquid, which may be water or a suitable alternative, is by means of a pump 30 , which are coupled to the flow lines and from the power supply of the Stirling cooler 22 or an independent power supply is pumped in the flow loop.

In the 8th shown cooling device shows the cooling system 29 in the middle of the chamber 24 such that the at least one component to be cooled 23 the cooling system 29 surrounds. In addition, other embodiments are possible in which the cooling system 29 in different configurations and lengths, depending on the spatial conditions implemented. For example, the cooling system 29 inside the walls of the chamber 24 be formed or form this. In such embodiments, the cooling system is 29 not in the middle of the chamber 24 arranged. Embodiments with the liquid-based cooling system 29 have an increased cooling efficiency, since the liquid of the at least one component 23 heat dissipates and they are the cold side of the Stirling cooler 22 over the heat exchanger 28 supplies. In addition, the use of a cooling liquid and possibly of insulated cooling lines allows a greater spatial separation between the Stirling cooler and the component to be cooled.

Instead of of the described free-piston Stirling cooler, other types of Stirling coolers can be used be inclusive those based on kinematic mechanisms, for example Dual Piston Stirling Radiator and Piston and displacer Stirling cooler.

According to the invention Stirling cooler used, to electronic devices, sources, sensors or other heat-sensitive ones Cool parts, who have to work downhole in the adverse environment. In these embodiments are the ones to be cooled Components in an insulating chamber, such as a dewar, arranged, and the cold end of the Stirling cooler is either directly or indirectly via a heat transfer mechanism coupled to one side of the chamber. The cooling device according to the invention can a significant amount of heat, for example, 150 W, dissipate. This makes it possible for the components to provide an environment below 125 ° C, even if the temperature in the borehole is 175 ° C. Model studies show that the embodiments according to the invention a cooling device with a stirling cooler in able to dissipate heat at a rate up to 400W.

Some aspects of the invention relate to methods of making a downhole tool having a cooling device according to the present invention. A schematic representation of a portion of a downhole tool including an inventive embodiment of a cooling device with a Stirling cooler is shown in FIG 2 shown. It will be understood that the embodiments of the invention are not limited to any particular type of downhole tool. Rather, the invention may be used with any sub-surface tool or instrument including wireline tools, LWD / MWD / LWT tools, spiral tubing tools, tubing tools, and for long term or permanent placement, such as in a well casing , for monitoring a reservoir.

9 illustrates a method of manufacturing a downhole tool according to the invention. The illustrated method 70 includes the step 72 by placing an insulating skirt or chamber in a downhole tool. The chamber may be a dewar or a chamber formed of an insulating material suitable for downhole use. The chamber may also be formed by a cutout on the insulating tool body. Subsequently, an electronic device, which must operate at relatively low temperatures, introduced into the insulating chamber, step 74 , Alternatively, the electronic device, a source for emitting electromagnetic radiation, sensors or the like may be placed in the insulating chamber before the latter is mounted in the downhole tool. Then a Stirling cooler is mounted in the downhole tool, step 76 , The order of arranging the Stirling cow Lers and the insulating chamber is not important, ie the Stirling cooler can be attached to the downhole tool in front of the insulating chamber. Preferably, the Stirling cooler is disposed adjacent to the insulating chamber. However, if space limitations do not permit placement of the Stirling radiator adjacent the insulating chamber, the Stirling radiator may also be spaced from the insulating chamber and a heat transfer mechanism interposed therebetween to conduct heat from the chamber to the Stirling radiator.

10 shows a method of cooling a sensor or electronics or the like arranged in a downhole tool. The procedure 100 includes a step 105 for providing a Stirling cooler in the downhole tool, adjacent to the sensor or electronics, and a step 110 for operating the Stirling cooler, in particular by supplying the Stirling cooler with energy such that heat is removed from the sensor or the electronic device.

Claims (14)

Cooling device for a downhole tool ( 20 ), characterized by a borehole tool ( 20 ) arranged insulating chamber ( 24 ) used to pick up an object to be cooled ( 47 ) and one in the downhole tool ( 20 ) arranged Stirling cooler ( 22 ), which removes heat from the insulating chamber ( 24 ) configured cold end and designed to dissipate heat hot end. Cooling device according to claim 1, characterized in that the Stirling cooler ( 22 ) is a free-piston Stirling cooler. Cooling device according to Claim 2, characterized in that the free-piston Stirling cooler has a permanent magnet ( 45 ) having. Cooling device according to one of claims 1 to 3, characterized by a power source for supplying the Stirling cooler ( 22 ), wherein the energy source is an on-surface electrical energy source, a downhole battery, a hydraulic power source, or a downhole power generator. Cooling device according to one of claims 1 to 4, characterized by a heat transfer mechanism ( 35 ) between the cold end of the Stirling cooler ( 22 ) and the insulating chamber ( 24 ), which is used to conduct heat from the insulating chamber ( 24 ) to the cold end of the Stirling cooler ( 22 ) is configured. Cooling device according to one of claims 1 to 5, characterized in that the insulating chamber ( 24 ) for providing an air flow in the vicinity of the object to be cooled ( 23 ) is configured. Cooling device according to one of claims 1 to 5, characterized in that the insulating chamber ( 24 ) for providing a liquid flow in the vicinity of the object to be cooled ( 23 ) is configured. Method for cooling a component arranged in a downhole tool ( 23 ), characterized by providing a Stirling cooler ( 22 ) in the downhole tool ( 20 ) in the vicinity of the component ( 23 ) and supplying the Stirling cooler ( 22 ) with energy such that heat from the component ( 23 ) Will get removed. Method according to claim 8, characterized in that as Stirling cooler ( 22 ) a free-piston Stirling cooler is used. Method according to claim 9, characterized in that a free-piston Stirling cooler with a permanent magnet ( 45 ) is used. Method according to one of claims 8 to 10, characterized that electrical Energy from an electrical energy source at the surface, one Battery in the borehole, a hydraulic energy source or a Energy generator is provided in the borehole. Method according to one of Claims 8 to 11, characterized in that the component ( 23 ) in an insulating chamber ( 24 ) in the downhole tool ( 20 ), the chamber ( 24 ) for providing an air flow or a liquid flow in the vicinity of the component ( 23 ) is configured. Method according to one of Claims 8 to 12, characterized in that a component ( 23 ) is used with a sensor. Method according to one of claims 8 to 13, characterized in that a component ( 23 ) is used with an electronic device.