MXPA97003404A - Apparatus and method for actively cooling instrumentation in a elev temperature environment - Google Patents

Abstract

The present invention relates to an apparatus for actively cooling instrumentation contained in a diagnostic tool, comprising: a) a first container having a cooling agent thereon, the first container being positioned adjacent to the instrumentation; ) a heat exchanger in thermal communication with the first container and the instrumentation, for transferring heat from the instrumentation to the cooling agent in the first container, c) a second container for receiving the heated cooling agent, and d) a compressor in communication with fluid with the first container, to extract the heated cooling agent from the first container and compress the heated cooling agent, the compressor is furthermore in fluid communication with the second container, to transfer the heated cooling agent compressed to the second container

Description

APPARATUS AND METHOD FOR COOLING INTO ACTIVE FORM INSTRUMENTATION IN AN ELEVATED TEMPERATURE ENVIRONMENT Field of the Invention This invention relates to an apparatus and method for cooling instruments in an apparatus while operating that apparatus in high temperature environments. In particular, it is related to the use of a cooling agent to cool the electronic parts in a tool of diag- nosis when the tool is exposed to temperatures of terrestrial formation and in this way prevent tool failure.

BACKGROUND OF THE INVENTION The environment found by downhole oil exploration tools can be very severe. Temperatures of up to and in excess of 2009C and pressures of up to 1.38x10 Pa are not rarer. Consequently, producers of petroleum exploration tools must design strong tools that can operationally support these conditions for periods of time. prolonged Probably the most difficult of all conditions to design electronics that can safely operate in high temperature environments. Conventional electronic components are usually rated to operate only up to around 125QC. In this way, it is necessary to create or experimentally find electrical components that can survive temperatures at the bottom of the well. Since the components are constantly changing through new manufacturing techniques, updating, etc., this process of creating electronic components is expensive, time consuming and never ends. In an effort to combat the high temperature requirement of electronics, the chassis or electronic compartments in downhole tools could be maintained at or below 125 ° C. At present, tools classified at 1755 are sometimes inserted into Dewar flasks when scanning for excess of 175 g C. The Dewar flasks act to isolate the electronics from the tool and to slow down the heating of the electronic chassis similar to a "large thermal bottle." The flask is a passive system that extends the residence time in the well of the tools in approximately Four to six hours often, the wellbore residence times required for exploration are much greater than those due to the expensive Matraz Dewar system.The problem at hand points to the need for an active cooling system that can maintain the electronic chassis at less than 1255C for extended periods of time.Conventional electronics could then be used without the need for costly high-temperature co-connectors.

Active cooling systems already exist for a variety of applications such as cooling of food products, motor vehicles and buildings. These active cooling systems, better known as air conditioners and refrigerators, can operate effectively for extended periods of time with little or no maintenance. A cooling system causes the heat to move. Take heat from one location and move it to another location. The location from which the heat was removed evidently becomes colder. For example, a refrigerator takes heat from the interior and moves it outside. The heat flows into the air and the interior, having lost heat, becomes colder. The active compression cooling systems of v¿ by work by evaporation. When a liquid becomes vapor, it loses heat and becomes colder. This change is because the vapor molecules need energy to move and leave the liquid. This energy comes from the liquid; the molecules left behind have less energy and so, as reused, the liquid is colder. For an active cooling system to work continuously, the same cooling agent (etc., Freon) must be used repeatedly for an indefinite period. These cooling systems have three basic patterns; the vapor compression system, the gas expansion system and the absorption system. The vapor compression system is the most effective and is used more extensively than the other provisions. The vapor compression system consists of four main elements: an evaporator, a compressor, a condenser, an expansion device. Referring to Figure 1, in the evaporator 1, the cooling agent boils (evaporates) at a temperature sufficiently low to absorb heat from a space or medium that is cooling. The boiling temperature is controlled by the pressure maintained in the evaporator, since the higher the pressure, the higher the boiling point The compressor 2 removes steam as it is formed, at a speed sufficiently fast to maintain the desired pressure. This steam is then compressed and delivered to a condenser 3. The condenser dissipates the heat to circulating water or air. The condensed liquid cooling agent, which is now ready to be used in the evaporator 1, is sharply reduced in pressure by passing it through an expansion valve 4. Here, the pressure and temperature of the cooling agent decrease until they reach the Dilution and evaporator temperature, thus allowing the cooling cycle to be repeated. During the expansion part of the liquid of the cold agent evaporates instantaneously to steam so that a mixture of liquid and instant steam enters the evaporator. In a cooling system, the low pressure in the evaporator is established by the cooling temperature to be maintained. The high pressure maintained in the condenser is finally determined by the available cooling medium (etc., the temperature of the circulating water or the air temperature of -atmosphere). The process is one in which the cooling agent absorbs heat at a low temperature and then under the action of mechanical work, the cooling agent is compressed and raised to a temperature high enough to allow rejection of this heat. The mechanical work or energy supplied to the compressor as energy is always required to raise the temperature of the system. To further explain the cooling process, the four main components are discussed in more detail. The evaporator 1 is the part of the cooling system in which cooling actually occurs. The liquid and steam cooling agent of the valve 4 of delivery are intorucen towards the evaporator. As the liquid evaporates, it absorbs heat at a low temperature and cools its surrounding media or media in contact with it. The evaporators can be direct expansion (acting directly to cool a space or product) or they can operate as indirect expansion units to cool a secondary medium, such as water or a brine which in turn is pumped to a more distant point utilization. A domestic refrigerator, for example, is a direct expansion unit in which its evaporator directly cools the air in the food compartment and also directly contacts the water trays used to make ice. Evaporators vary widely in design, with those used to cool air often made as continuous pipe coils, with fins mounted outside the tubes to provide more surface contact to the air being cooled. For cooling fluid, such as brine water, the cuirass and tube dosing is common. In this case, the brine passes through the tubes surrounded by the cooling agent of evaporation (evaporation), which is contained in the cylindrical shell m_yor. The brine tubes, in turn, are welded or laminated to pipe ends at the end of the shell to prevent leakage of the cooling agent from the shell or into the brine circuit. The expansion valve 4 feeding the evaporator should control the flow so that sufficient cooling agent flows into the evaporator for the cooling load, but not in such excess that the liquid passes over the compressor, with the possibility of causing damage to it. The compressor 2, the key element of the system, can be activated by means of an electric motor, steam engine or internal combustion, or steam or gas turbine. Most compressors are of the reciprocating type (piston) and vary from fractional horsepower energy, such as those found in domestic refrigerators or in small air-conditioning units, to large, multi-cylinder units that serve to large industrial systems. In these large multi-cylinder units, the capacity can be controlled with automatic devices that prevent certain cylinders from closing. For example, in a six-cylinder unit, if the valves are kept open on two of the cylinders to keep them inoperative, the capacity of the machine is reduced by a third when operating at normal speed. Centrifugal compressors are used for cooling units. These compressors use impellers - centrifuges that rotate at high speed. Centrifugal compressors depend for their compression to a large extent on the action-dynamics of the gases themselves as they flow in the diffusion passages of the compressor. These compressors can be large centrifugal compressors made with a single impeller or with two to four or more impellers in series, to compress the gas through the required scale. These compressors are used extensively for large air conditioning installations and also for use in the industrial field when gases are compressed for liquefaction or for transprotection, such as in the natural gas industry, and when the air is compressed to produce oxygen or liquid nitrogen. The condenser 3 of the steam system must dissipate the value of the hot steam it receives from the compressor and condense this vapor to liquid for new use by the evaporator. The condensers dissipate heat to the ambient atmosphere through their surfaces externally with fins or by means of a shell and tube arrangement in which the steam delivers heat to a circulating fluid (water, etc.) which passes through. of tubes that make contact with the cooling agent vapcr. The steam temperature is maintained above that of the surrounding water or air by compression to ensure that heat is transferred to the refrigerant.; in this way, when the steam is left ex pander, its temperature drops well below that of the cooling agent. Double tube condensers are also used. In these units, the vapor and condenser of cooling agent pa in a direction through the annular space between 1 or two t, while the water, which flows in the opposite direction to-through the central tube, performs the cooling function. The concept of air conditioning works on the principle of exchanging heat of a substance heated a cold substance. In this principle, the temperature of a hot substance (such as a fluid) is transferred to a cold flow. As the temperature of the hot fluid decreases, the temperature of the cold fluid increases. Thermal exchangers are manufactured in many different designs and are widely used in various industries. Thermal exchangers are given different names when they serve a special purpose. In this way, boilers, evaporators, superheats, condensers and coolers can all be considered interchangeable heat exchangers. An example of a heat exchanger is illustrated in Figure 2a and explains the basic operation of a heat exchanger. This exchanger is constructed from two tubes 5 and 6 in a concentric arrangement. Inlet and outlet ducts are provided for desfluids. In the scheme, the cold fluid flows through the inner tube 7 and the hot fluid through the inlet tube 5 in the same direction through the annular gap between the outer tube and the inner tube. This disposition of flow is called parallel flow. In the same the heat is transferred from the hot fluid through the wall of the inner tube (the heating surface) to the cold fluid. Temperature in both fluids varies as shown in Figure 2b. In trace 9, the hot fluid temperature decreased from t ^. to t ^. In trace 10, the temperature of the cold fluid to mint of t. a t «. The amount of heat Q that is transferred from one fluid to the other per unit of time, called heat flow, can be calculated from the following equation mc (t. t,) (D This equation shows that the heat flux 0 { kW) can be obtained by multiplying the mass by unit of fluid time (m (kg / sec) by the specific heat c (KJ / kg-sC) of the fluid and by any increase in temperature t1 - t2 (QC) of the input fluid at the outlet of the thermal exchange The specific heat is a property of the fluid involved and its current state The amount of heat left by the hot fluid must be the same as the amount of heat received by the cold fluid. Flux of mass and the increase of temperature for the cold or the arrangement for the hot fluid, therefore, can be recorded in equation (1) .The heat exchanger may have to be taught, for example, to increase the temperature of a prescribed mass per unit of time m2 of cold fluid of t.at.This value in equation (1) then determines the flow Q of heat that has to be transferred in the thermal exchanger. the following discussion to calculate the heating surface of the exchanger. The temperature difference / ^ t ,, between the fluids at the inlet of the heat exchanger decreases to the value / jt? at the exit, as illustrated in Figure 2a. A heat exchanger is operated in counterflow when the direction of one of the fluids is reversed. The counterflow arrangement has the advantage that the outlet temperature t. The cooler fluid can be increased beyond the outlet temperature t 2 of the hot fluid. In addition, a smaller surface area in counterflow is required than in parallel flow to transfer the same heat quantity. This is because the average temperature difference -? > tm in the backflow heat exchanger, par flow of heat determined and the pre-entered inlet temperatures, is higher than in the parallel flow exchanger.

The heating surface of the heat exchanger can be obtained from the equation: The equation indicates that the required surface area A (m) is or has been dividing the heat flux 0 obtained with the equation (1) between the U coefficient of total heat transfer and the difference in mean temperature. The larger heat exchangers use a beam of tubes through which one of the fluids flows.The tubes are enclosed in a shell with provisions for other fluid to flow through the spaces between the tubes.The fluid flowing out of the tubes can be directed either in the same direction or against the actual flow in the tube bundles.In the last arrangement, the parallel or opposite fl ash can be approximated in the manner shown in Figure 2. In another arrangement, the cold fluid is distributed. In such a way that it flows in parallel through the pipes, it controls the heating surface and is then collected by means of a collector.This arrangement creates a cross-flow, as shown schematically in FIG. Figure 2. In nuclear reactors the fuel rods can replace the tubes, and the cooling fluid flowing through the rods eliminates the heat generated by the fission process. Similarly, rods containing electric resistance heaters can supply heat to the fluid passing through the intercalator between the rods. As mentioned above, there is a need for a downhole cooling system that can keep the electronics of the diaphragm tool cold in order to avoid tool failure from the extreme temperatures of the bottom of the well. There have been efforts to apply the cooling concept to downhole tools. In 1977, Mechanics Research tried to develop a system that incorporated a refrigeration technique to be used in a geothermal well. The design of the system was a closed system that would operate continuously, similar to the refrigerator cooling concept of Figure 1. However, the specific objective of the project was to develop a compressor for said system. The project did not achieve its main objectives. Therefore, there is still a need for a system that can actively cool instrumentation in a high temperature environment.

SUMMARY OF THE INVENTION In the present invention, a continuous cooling system allows constant low-pressure vaporization of a water tank while it is in thermal communication with the bottom-well logging-machine electronic chassis. The tool electronics and a lower water tank are in thermal communication with each other through a cold heat exchanger. The heat of the electronics, as well as that -from the bottom of the hot well (until approximately 2005C) causes the water in the lower tank to boil or vaporize to vapor. As the water evaporates, the vapor is removed from the tank. compresses through a compressor to a superior tank. By moving the steam from the lower tank as it is generated, its resulting pressure and temperature can be regulated and thus regulate the temperature of the electronic components. For example, the temperature of the lower tank can be maintained at approximately 1005 C if its internal pressure is maintained at approximately 1.01 x 10 Pa. The steam in the upper tank must be compressed at a pressure greater than the saturation pressure of the tank. at the temperature of the well in order to empty the lower tank. A well of 200QC would require a pressure of 1.55 x 10 Pa. Once the steam enters the upper tank, it is allowed to cool to the temperature of the well. A control system between a lower tank pressure sensor and the compressor maintains a constant pressure evaporation in the lower tank. Once the lower tank empties of water, the system runs out and the tool must return to the surface and the tank be filled. Likewise, the upper tank must be emptied before the tool re-enters the well. Three main subsystems are combined in the present invention as shown in Figure 3. The subsystems are the compressor 11, the cold thermal exchanger 10 (evaporator) and the hot thermal exchanger 12 (condenser). cordless electronics that includes heat dissipation electronics An outline of the present invention in its simplest form is shown in Figure 4. The evaporator 17 encompasses a lower water tank 16 stored in thermal contact with a heat exchanger 18 cold, the electronics are all inside a 15 Dewar flask, this system allows the heat from the conduction to the flask and the electronic component dissipation to be transferred to the water tank, consequently the water starts to evaporate. The second main component is the compressor 23. The compressor keeps the lower tank 17 at the specific atmospheric pressure value. to this task by pulling the vaporized water or steam out of the lower tank and transporting it to the upper tank or hot thermal exchanger, outside the Dewar flask. In this way, the compressor must reach pressures greater than or equal to the water saturation pressure at a determined well temperature, together with the current flow regimes produced by the total cooling load. For example, the worst case of a 2009C well requires compressor output pressures equal to or greater than 15.5 x 10 Pa and a flow rate equal to 3.5 x 10 kg / s to the cooling load of 80-W. The super thermal / interca biadro 24 thermal tank is simply a tank to which compressed steam is transported and allowed to condense at the drilling temperatures. The volume of the upper tank must be at least 1.16 times larger than the lower tank due to the specific volume - increased water saturated at 200 ° C above that at 100 ° C. In addition, with knowledge of thermal transfer coefficients of the worst case in the downhole system, the upper tank must be thermally conductive towards the well. The thermal transfer of the cooling load and the compressor work should be achieved with a tamper as small as possible over that of the well.

Brief Description of the Drawings Figure 1 is a schematic representation of the components of a cooling concept for cooling. Figure 2 is an isometric cross-sectional view of a parallel flow heat exchanger. Figure 2b is a graph of the changes in fluid temperatures occurring in the parallel heat exchanger. Figure 3 is a diagram of the one-step hybrid vapor compression system of the present invention. Figure 4 is a diagram of the active cooling system of the present invention. Figures 5a-5d represent a diagram of a sample electronics chassis. Figures 6a-6d depict a diagram of a cold heat exchanger. Figures 7a-7c depict a diagram of the cold heat exchanger and lower tank assembly of the present invention. Figure 8 is a diagram of a compressor assembly Figures 9a-9b depict a diagram of the lubrication assembly of the present invention. Figure 10 is a diagram of the upper heat exchanger tank assembly of the present invention Figures 11 a-11 c represent a diagram of the compressor / motor assembly.

Detailed Description of the Invention The total assembly of the invention is shown in Fig. 4 and includes the sample electronics 16, the cold exchanger 19 / lower tank (evaporator), the compressor 23, the lubrication system and the exchanger 24 hot thermal / upper tank (condenser). The invention is described in the context of a designed and manufactured prototype of the invention. Even when they are not compatible with the bottom of the well, aluminum pieza was used in the prototype. Use aluminum in the lower and upper tank tubes, and the compressor valve head part. In practice, the upper tank tubes and the compressor valve head piece should not be made of aluminum in an oozo bottom design. Figures 5a-5d show the electronic chassis assembly containing electronic tooling of the diag.

The detailed drawings are provided in the Applicant's publication entitled "Active Cooling for Electrons in Oil Line Exploration Tool", Massachusetts Institute of Technology, June 1996. The chassis has a base 30 made of aluminum. The diameter and lengths of the chassis are 0.0699 m and 0.43 m, respectively. The end plates 31 and 32 are connected to the chassis base 30 by screws 35. The end piece 31 is connected to a bottom tank and, therefore, is shorter in length than the end foot 32. A set 34 of instruments containing electronic components is fixed to the chassis as shown. It is fixed to the base through screws 36. The set of instruments contains the electronic components 37. In the test structure, the Kapton Strip heaters serve as the electronic parts. These heaters have a resistance of 16.6 ohms and when connected in parallel they have a total resistance, R. of 6.4 ohms at a temperature of 100 - C. The sample electronics are activated by a power supply of C Hewlett Packard # 6443B. The voltage, V.p? At., Required to produce an electronic heat dissipation, PhO. +, Is equal to: heat ^ PheatRl (3) Electronic heat dissipation valves between 0"and 50 are available with the given power supply.

Figures 6a-6d show the cold-heat exchanger assembly. As shown, the electronic chassis 40 has a chassis base part 30, electronic sample end pieces 31 and 32 fixed to an instrument assembly 34. Also shown is a portion of a cold heat exchanger 41 adjacent to the electronics 37. The heat pipe retainer 42 contains heat pipes 43. The heat pipes 43 are mounted in the fastener channels. A heat pipe clamp 44 secures the tubes to the fastener 43. The screws 36 and 46 secure the heat exchanger and the heat pipe clamp. In Figures 7a-7c, prototype 39 of heat exchanger has 0.457 m by 0.065 by 0.00660, Flat heat pipes 43 TPhcBS by Noren Products mounted on an aluminum fastener 42 which is placed on a thin, thermally conductive conductive pad (Berquist Co. Sil Pad 400) insulator 47 - on the Kapton strip heaters 37. The heat pipes transfer the heat from the electronics 37 to the water contained in the lower tank 50 through a matching pey tile 54. The matching piece 54 is in contact with the heat pipes 43 through the heat exchanger portion 41. A screw 56 fixes the heat exchanger to the lower tank. The air spaces between the heat pipes, nipple fastener and matching aluminum part are removed by filling these spaces with a Dow Corning 340 thermally conductive thermal sink compound. An O-ring 55 provides a seal between the lower tank and heat exchangers - to prevent the flow of water to the electronics. Two other junctions 53 and 53b are located at the end 51 above the well and the end 52 at the bottom of the lower tank well. The lower tank 50. is sized to fit into the matrix and carry 1 kg of water. The volume of the lower tank is 3 of approximately 0.001 m. However, when the system is installed in the horizontal position with the tank outlet in the center of the cross section, the effective volume of the tank is halved. In this way, only 0.5 kg of water can be carried in the lower tank in the horizontal tests The flask used in the present invention is a Dewar UDFH-KA manufactured by National K-Works. The properties of the flask and the diameter dimension diagrams are detailed in Chapter 3 of the dissertation. of the inventor entitled "Active Cooling for Electronics in a Wireline Oi 1-Exploration Tool", Massachusetts Institute of Technology, June 1996. The flask has a total length of 2.36 m and an isolated payload or longevity of 1.71 m. The ends of the flask are insulated with Teflon cutouts. Figure 8 shows the compressor assembly used in the active chiller. The compressor is composed of several mechanical parts. The outer housing 60 of the compressor ra contains two volumes: the compression chamber 61 and the crankshaft bed 62. In the compressor chamber there is a piston 63, piston rod 64, piston cylinder 65 and valve head part 66. The piston cylinder guides the stroke of the piston. The piston / cylinder seal is a dynamic overlapped design with the piston made of methanite and the cylinder made of 12L14 steel. These parts are manufactured for approximately 126 million strokes at a temperature of 232QC. These specifications equal a time at the bottom of the well of approximately 1000 hours at co-operator speed speeds of 2000 rpm. The intake port 67 is positioned at the bottom of the piston stroke and the exit port 68 is positioned at the top of the psiton stroke. In operation, as the piston travels downward, a small vacuum is created in the compression chamber. The port 67 is exposed as the piston crosses its surface and steam is sucked into the volume of the compression chamber. During the upward stroke of the piston, the port 67 is sealed by the circumferential area of the piston and lubricant. The steam is compressed by the upward movement of the piston. This high pressure steam exits through the compression valve in its head 66 and port 68. A miniature retention valve 69 is placed in the valve head part and serves as the valve-discharge in the compressor. The valve is mounted hard on the head piece of comrpesora. A miniature spacer 70 and a Lee mechanical tail 71 hold the check valve 69 in a pressure sealed position. To filter the large particles from the steam flow, a small 40 μm filter from Mectron Industries, is placed in front of the miniature holding valve and the valve head piece on the inlet side of the chamber. The filter prevents contaminants from entering and plugging the valve, especially during a period of seal penetration. In this design, an intake valve is eliminated, together with this design some complexities and inefficiencies. The valve head part 66 utilizes a seal-vitor durometer 95 to isolate the volume of the pressure chamber from the environment. The piston stroke is controlled by turning the crankshaft assembly. The crankshaft assembly is made from a crankshaft 75, bearings 76 and 76b, a rotary seal 77 and a pin 78 welded to the arrow, in operation, the crankshaft pin 78 is inserted into the piston rod 64. When the crankshaft is rotated, the piston 63 moves up and down. Two different bearings 76 and 76b, but conventionally sized balls guide the rotation of the crankshaft. A revolving Greene-Tweed steam seal 77, spacer 79 and bearings 76 are contained in the compressor assembly-by an end piece 82 held in place by six warped head screws. The storks are held inside the compressor by an end oeiza 80 which is held in place by three socket head screws. This end piece also uses a viton 84 toric 95 gasket for pressure isolation between the compressor interiors and the environment. For compatibility with the rotary seal, -the hardness of 45-55Rc is specified for the crankcase. As mentioned above, the piston connecting rod is taken directly from the Fox size 40 motor. Figures 9a-9b show the lubricating system for the compressor. This system has a lubricator tube 85, with a lubricating part 86. The lubricant in the tube is kept under pressure and compensated by two springs 87 in series. These -resorts 87 are separated by a spacer 88. The resor ts are contained at one end by the end piece 89. The end piece and the lubricator part use an O-ring 90 and 90b viton durometer 95 for pressure isolation from the environment. The other end of the springs is contained by a piston 91. The springs apply force to the piston which then applies pressure to a lubricant stored on the other side of the piston. The piston maintains the lubricant seal with a vitur 90c O-ring 90c durometer 95. A three-stage, normally closed, three-pass solenoid valve Lee-Co. Lee periodically opens and closes as a function of time, showing that the lubricant It travels in the compressor intake line through a restrictor 94 Visco-Jet from Lee Co. The restricting peice restricts the flow of lubricant to lower flow regiemens than those of the solenoid valve alone. Both the restrictor and the valve are placed on the lubricator part. From the intake line, the cleaner runs into the compression chamber of the compressor and maintains the dynamic overlap pressure seal. Some lubricant also "leaks" the seal and serves to lubricate the interior of the crankcase. A hydraulic line is connected to the lower line in the lubricant part that contains the solenoid valve and was used to fill the lubricant reservoir before operation. The lubricant inlet line is then plugged during the operation. The lubricant is pumped periodically to the reservoir under pressure. The tank pressure is measured by a pressure gauge. In practice, a unscrewing system could autonomously maintain the deposit pressure. The lubricant used in the final tests was Silicon 500cST oil from Dow Corning-200, however, the lubricant selection should be based on trying to maintain the best seal. A piston / cylinder seal model showed the need for a viscosity of approximately 50cSt at the operating temperature and arrow speeds of the compressor. The motor assembly is used to rotate the compressor crankshaft. The motor shaft is connected to the compressor shaft by means of a universal gasket. The motor housing and compressor housing are connected by a spreader and held in place by eight socket head screws.

The hot heat exchanger / tank-top assembly is shown in Figure 10. The assembly comprises an upper tank 100, ends above the hole 101 and below the hole 102 of the toric joints 103 and 103b, and serves both to steam balance at high pressure with driving heat from the steam to the well through its walls. As mentioned earlier, the tank is made of aluminum that is not compatible with the downhole environment. However, the aluminum housing does not differentiate from a heat transfer point of view in the design. In other words, the limiting resistance to thermal conduction is the borehole film coefficient, not the upper tank material. The difference in temperature required for the aluminum housing is only 0.35C less than that required for the housing of stainless steel compatible with the bottom of the well. The original downhole / compressor motor assembly is shown in Figures 11a-11c. The motor assembly is a conventional motor containing main parts such as a motor assembly 110, a motor end 111, an engine add arrow 112, a motor 113 out of pump, a motor housing 11, a spacer 115 , who carry out convention operations. An end 116 'universa 1 and end 117 female for connecting the motor to the compressor and providing the means by which the motor dries the compressor. The universal joint is connected to the compressor by the male end 119. The assembly has an outer diameter of approximately 0.102 m. The 2 / 3HP high temperature wellbore motor showed in the assembly that it is a motor commonly used in wireline tools. The development of a new engine to fit the geometric constraints does not represent a serious design challenge. However, due to time and cost, a new site fund was not purchased for the prototype above the well. The method and apparatus of the present invention provide a significant advantage over the prior art. The invention has been described in relation to the preferred modalities at the time of presentation. However, the invention is not limited thereto. The selection of particular materials should be based on the environment in which the device will operate. Changes, variations and modifications to the basic design can be made without abandoning the inventive concept in this invention. In addition, these changes, variations and modifications will be evident to those experienced in the field that have the benefit of the previous teachings contained in this application. All these changes, variations and modifications are intended to fall within the scope of the invention which is limited by the following clauses.

Claims (20)

CLAIMS:

1. (- An apparatus for cooling instrumentation contained within a diagnostic tool comprising: a) a first container having a cooling agent thereon, the container being positioned adjacent to the instrumentation; b) a heat exchanger in thermal communication with the first container and the instrumentation for transferring the instrument's temperature to the cooling agent in the recirculator; c) a second container for receiving the heating agent from heating; and d) a compressor in fluid communication with the first container for pumping heated cooling shaft of the first container and in fluid communication with the second container for pumping the heated cooling agent to the second container.

2. The apparatus of claim 1, wherein the first and second containers are near and far from tanks, respectively, relative to the instrumentation.

3. The apparatus of claim 2, wherein the lower ta is connected to the instrumentation through the thermal exchanger.

4. - The apparatus of claim 2, further comprising an insulated flask for containing the lower tank, the heat exchanger and the instrumentation.

5. The apparatus of claim 4, wherein the in- trocution is electronic circuits.

6. The apparatus of claim 1, wherein the in cold state is water.

7. The apparatus of claim 6, further comprising a vapor control system for maintaining a constant pressure vaporization of the cooling agent in the lower tank.

8. The apparatus of claim 7, further comprising a pressure controller for maintaining the pressure in the upper steam tank that results from the heating of the cooling agent.

9. The apparatus of claim 8, wherein the steam pressure is measured by a pressure gauge within the lower tank.

10. An apparatus for actively cooling instrumentation contained in a logging tool comprising: a) an element for containing a cooling agent the element being placed adjacent to the instrumentation; b) an element for transferring the heat of the instrumentation to the cooling agent in the container element c) a second element for containing an en-cooling agent after the cooling agent has been heated and transferred from the first element from recipeinte; and d) a cooling agent transfer element in fluid communication with the first and second container elements for transferring the heated cooling agent from the first container element to the second container member.

11. The apparatus of claim 10 further comprising an insulated element for containing the lower tank, the heat exchanger and the instrumentation.

12. The apparatus of claim 10, wherein the cooling agent transfer element comprises a compressor element and a vapor control element.

13. The apparatus of claim 12, wherein the control element is positioned so that the control element controls the steam entering the compressor element and the va by exiting the compressor element.

14. The apparatus of claim 10, further comprising a pressure sensing element for detecting cooling agent pressure when cooling is transformed from a liquid state to a vapor state.

15. A method for actively cooling instrumentation contained in a logging tool, comprising the steps of: a) transferring heat from the instrumentation to a cooling agent stored in a tank adjacent to the electrons; b) maintaining the temperature of the cooling agent at about the boiling point of the cooling agent; and c) control 1? temperature of the instrumentation through the cooling agent so that the temperature of the instrumentation is approximately the same as the temperature of the cooling agent.

16. The method of claim 15, wherein the temperature of the cooling agent is maintained: - by allowing sufficient heat to be transferred to the cooling so that the cooling agent starts <Boil and evaporate; - transferring the evaporated portion of the cooling agent out of the tank; and - transferring the vaporized cooling agent to a condensation tank.

17. The method of claim 16, wherein the vaporized portion of the cooling agent is transferred from the tank by: - pumping the vaporized cooling pad of the cooling tank, and - regulating the flow rate of the vaporized agent to from the cooling tank to maintain a desired vapor pressure.

18. - The method of claim 17, wherein the vaporized cooling agent is maintained at a pressure of about 1.01 x 10 Pa.

19. The method of claim 16, further comprising the step of condensing the vapor to the Cooling 1 fluid.

20. The apparatus of claim 1, wherein the compressor is a positive displacement steam compressor.