Patent Publication Number: US-6659204-B2

Title: Method and apparatus for recovering core samples under pressure

Description:
CROSS-REFERENCED TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 09/124,406, filing date Jul. 29, 1998, now U.S. Pat. No. 6,216,804. 
    
    
     BACKGROUND 
     1. Field of the Invention 
     The present invention relates generally to a method and apparatus for retrieving subterranean core samples under pressure and, more specifically to a method and apparatus for recovering core samples under insitu pressure and temperature. 
     2. Background of the Invention 
     The recovery of subterranean, geologic samples is commonly performed by an operation or technique referred to as coring. This technique has evolved from simple single tube systems to dual tube systems that are most commonly used in the mining and petroleum industry today. Because such coring techniques are employed for recovery of volatile components contained within rock samples, various modifications have been made to conventional coring devices in order, for example, to retain formation pressure on the core during recovery. 
     In order to accurately analyze the composition of certain volatile core samples, the core sample must maintain its chemical, mechanical, and/or physical integrity during the retrieval process. Downhole, water or other substances in the formation may contain dissolved gases which are maintained in solution by the extreme pressure exerted on the fluids when they are in the formation. Thus, unless a pressure core barrel is employed during the core extraction process, the pressure on the core at the surface will differ dramatically from the pressure experienced on the core sample downhole. Furthermore, as the pressure on the core sample decreases, fluids in the core will expand and any gas dissolved therein will come out of solution. Accordingly, the retrieved core sample will not accurately represent the composition of the downhole formation. 
     One common method of retaining core integrity is known as pressure coring. Pressure coring utilizes various apparatuses to maintain the core sample at or near formation pressure as the core is retrieved to the surface. Core sampling tools that include pressurized core barrels have been known for several decades. For example, U.S. Pat. No. 2,248,910 to D. W. Auld et al. entitled “PRESSURE RETAINING CORE BARREL” discloses a core barrel that is sealed downhole to maintain the core at downhole pressure. U.S. Pat. No. 3,548,958 to Blackwall et al. discloses another pressure core barrel that utilizes a compressed gas system to maintain pressure on the core sample during the core retrieval process. U.S. Pat. No. 4,317,490 to Milberger et al. discloses yet another pressurized core barrel in which a ball valve, actuated from the surface is employed to trap ambient pressure in the core barrel while downhole. U.S. Pat. No. 4,466,495 to Jageler discloses a pressure core barrel of a sidewall coring tool. Other pressure core barrels are disclosed in U.S. Pat. No. 4,356,872 to Hyland, U.S. Pat. No. 4,256,192 to Aumann, the inventor of the present invention, U.S. Pat. No. 4,230,192 to Pfannkuche, U.S. Pat. No. 4,142,594 to Thompson et al., U.S. Pat. No. 4,014,393 to Hensel, Jr., and U.S. Pat. No. 4,735,269 to Park et al. Pressure core barrels often utilize pressure actuation to release a latch and/or mechanical manipulation of the drill pipe to close a valve and also often require the entire core barrel to be brought to the surface to recover the core. 
     Encapsulation is another technique known in the art to maintain the integrity of unconsolidated or friable core samples. In U.S. Pat. No. 4,449,594 to Sparks, a foam is introduced into the well under a correlated control pressure. The core sample is thus encapsulated while the reservoir pressure within the sample is balanced by the bottom hole foam balance pressure to produce a balanced, pressurized core sample. Another method of encapsulating a core sample is disclosed in U.S. Pat. No. 4,716,974 to Radford et al. in which a liquid foam is allowed to cure to form a sponge-like solid that retains oil as the core is depressurized during retrieval. Another attempt to stabilize cores where unconsolidated and friable columnar masses of earth can be handled without altering the characteristics of its physical structure employs a rubber sleeve that encapsulates the core sample. A housing is provided for positioning the ensleeved core therein and subfreezing material is circulated around the ensleeved core to freeze and solidify the core fluids contained therein. Likewise, in U.S. Pat. Nos. 5,360,074, 5,560,438, 5,546,798, and 5,482,123 to Collee et al., methods for maintaining the mechanical integrity and for maximizing the chemical integrity of a core sample during transport from a subterranean formation to the surface comprises employing an encapsulating material that increases in viscosity or even solidifies at temperatures slightly lower than those expected downhole. The patents to Collee note that in such a method of encapsulation, the chemical integrity of the core sample can be further increased by using a pressure core barrel. 
     Certain core samples, however, such as cores containing methane hydrate, not only require that the core sample be maintained at formation pressure when brought to the surface for examination and testing, but because methane hydrate is a material stable only within a limited pressure/temperature range, the core sample must also be maintained at formation temperature during recovery. If the core sample is allowed to become heated above this pressure/temperature envelope during the extraction process, the structural and physical makeup of the sample will be partially if not totally lost. 
     One attempt in the art to retrieve methane hydrate cores is disclosed in U.S. Pat. No. 4,371,045 to McGuire et al. As described, the cores are cooled down to at least −80 degrees C. at which temperature the pressure of methane hydrates is 1 atmosphere. Such cooling is accomplished by employing a conventional wire line retrievable core barrel having perforations therein through which cryogenic liquid passes into direct contact with the hydrocarbon hydrates and thus thermodynamically stabilizes the core. The invention employs an insulated chilling vessel into which the perforated core barrel and thus the core sample is moved for cryogenic freezing. 
     Many of the aforementioned coring apparatuses employ valves or other sealing devices to isolate the core. For example, a common method of preventing fluid access to the inner tube of a core barrel assembly is provided in U.S. Pat. No. 5,230,390 to Zastresek et al. in which a closure mechanism is configured to move from an open condition to a closed condition in response to increased fluid flow rates and pressure differentials occurring at the closure mechanism. Likewise, U.S. Pat. No. 5,253,720 to Radford et al. discloses a coring device in which a ball valve is actuated to seal off the core barrel before the core barrel is pulled to the surface. 
     It is also noted, that wire line retrieval of core barrels and/or manipulation of various components of the coring apparatus has previously been employed in many of these systems. For example, in U.S. Pat. No. 3,627,067 to Martinsen, a core-drilling system is disclosed in which selective or controlled release of an overshot from the core barrel while downhole is performed by pumping a wire line to which the overshot is attached up and down a prescribed number of times. In U.S. Pat. No. 3,667,558 to Lambot, an upward pull on a cable unlatches the coring head and also vents water under pressure so that it no longer forces the assembly downward. Continued pulling on the cable retrieves the coring head and the core sample. U.S. Pat. No. 3,739,865 to Wolda, discloses a wire line core barrel system that includes flexible latch fingers and provides a predetermined pressure signal indicating latching and further blocks fluid flow until the core barrel is properly latched. U.S. Pat. No. 4,800,969 discloses yet another wire line core barrel assembly in which an inner tube assembly can move down faster than the fluid flow in the drill stem during the time the inner tube assembly moves downwardly in the drill stem. U.S. Pat. No. 4,466,497 to Soinski et al. discloses yet another wire line core barrel apparatus. 
     Other coring systems and devices are known such as the coring apparatus disclosed in U.S. Pat. No. 3,874,465 to Young et al. in which core samples of relatively soft formations may be retrieved. The coring apparatus comprises a core barrel with an interior surface having properties similar to synthetic rubber, two semi-tubular rigid portions joined along the adjacent edges by a flexible material, and a core catcher having a plurality of flexible segments adapted to open while the core is being drilled and to close when the core is to be recovered. A latch for retaining the tool in position within the coring bit and a swivel allowing the core barrel and catcher to remain stationary while the coring bit is rotated are also provided. 
     While the aforementioned references disclose various methods and apparatuses for retrieving core samples of subterranean formations, these methods are inadequate to maintain a core sample at least partially comprised of methane hydrate at its downhole state. U.S. Pat. No. 4,371,045, which is specifically directed to the problem of stabilizing hydrocarbon cores, requires that the core be quickly brought to the surface before cryogenic freezing of the core is performed. Thus, it would be advantageous to provide a method and apparatus for retrieving core samples that are or become unstable when removed from the downhole environment. Such a coring method and apparatus may be applicable to not only obtaining core samples of formations containing hydrocarbons, but may have utility in other coring applications where the core samples may be unconsolidated, friable, or comprised of frozen material that would otherwise not maintain their chemical or mechanical properties once exposed to ambient pressures and temperatures. In addition, the methods and apparatuses disclosed herein may have applicability to other coring devices regardless of the type of formation from which the core sample is being taken. 
     SUMMARY OF THE INVENTION 
     Accordingly, it is an object of the present invention to provide a method and apparatus for retrieving geological core samples in which the core samples are recovered at in situ pressure. 
     It is another object of the present invention to provide a method and apparatus for retrieving geological core samples in which the integrity of the core sample is maintained by cooling the core sample as it is brought to the surface. 
     It is an object of the present invention to provide a method and apparatus for retrieving geological core samples in which heat is diverted away from the core. 
     It is yet another object of the present invention to provide a method and apparatus for retrieving geological core samples in which the core sample can be safely extracted into a transfer, storage, or other laboratory container while maintaining in situ pressure on the core. 
     It is still another object of the present invention to provide a method and apparatus for retrieving geological core samples in which the system is easily repairable. 
     Another object of the present invention is to provide a method and apparatus for retrieving geological core samples in a nearly continuous coring operation in which downtime is significantly reduced. 
     Still another object of the present invention is to provide a method and apparatus for retrieving geological core samples in which the system is reliable and relatively easy to test, maintain, and operate. 
     Yet another object of the present invention is to provide a method and apparatus for retrieving geological core samples in which the system is capable of various modes of operation depending on the needs of the operator. 
     Additional objects and advantages of the present invention will be apparent from the description and claims which follow or may be learned by practicing the invention. 
     Accordingly, the foregoing objects and advantages are realized in an improved method for coring and coring tools for recovering core samples under pressure comprising an inner barrel having a first end and a second end. A remotely actuable valve is connected to the inner barrel at the second end and a removable plug is attached to the first end of the inner barrel. The inner barrel, the valve, and the plug define a pressure or core sample chamber. 
     The coring tool further includes a cooling system associated with the inner barrel for cooling the inner barrel during retrieval of the core sample to the surface. Preferably, the cooling system comprises a plurality of thermal electric coolers which cool an inner tube of the inner barrel. The thermal electric coolers are thus disposed along a portion of the inner tube. 
     In another preferred embodiment, the cooling system comprises a plurality of heat pipes extending around and along the inner tube of the inner barrel. The heat pipes may be contoured to match the shape of the inner tube for maximum efficiency in extracting heat from the inner tube. 
     The cooling system may also include a power source for providing electric current to a plurality of cooling elements and for providing power to a pump employed to circulate a coolant through the heat pipes. 
     The coring tool further preferably includes a core catcher associated with the inner barrel at an end thereof for holding a core sample within the inner barrel as the inner barrel is lifted relative to the borehole bottom. The core catcher may be comprised of a dog catcher, a basket catcher, or other types of core catchers known in the art. 
     The coring tool is further preferably provided with a pressure system for maintaining the pressure of the core sample at or near in situ pressure during the recovery operation when the core sample is brought to the surface. In a preferred embodiment, the pressure system comprises a piston disposed and slidable within an elongate chamber. The elongate chamber is in fluid communication with the core sample chamber at the end of the elongate chamber nearest the core sample chamber. 
     Preferably, the coring tool includes an outer barrel disposed about an inner barrel and further includes a coring bit secured to a distal end of the outer barrel. A sub is provided which secures the outer barrel to the inner barrel. The inner barrel comprises an outer tube and an inner tube. A swivel mechanism is preferably interposed between the outer tube and the inner tube to allow the outer tube to rotate with the rotation of the outer barrel and drill bit during drilling operations while the inner barrel system remains relatively stationary. 
     In a preferred embodiment, the inner barrel system comprises the core catcher, the core sample or pressure chamber, the pressure control system, and the temperature control system. The inner tube is selectively longitudinally movable relative to the outer tube for lifting the core and closing the valve. Preferably, the valve is a ball valve comprising a ball housing, a ball having a bore extending therethrough and pivotally disposed within the ball housing, and a linkage mechanism interconnected between the ball and the outer tube for closing the ball when the outer tube moves longitudinally relative to the inner tube. A catch mechanism is also provided for engaging a ball valve operator when the inner tube assembly is longitudinally moved relative to the outer tube assembly. The catch mechanism is preferably spaced a sufficient distance from an engageable point of the ball valve operator to allow a distal end of a core sample to pass completely through the ball valve before the ball valve is closed. 
     This relative longitudinal movement is preferably accomplished by employing selectively releasable latching mechanisms for selectively securing the inner tube system to the outer tube system. In addition, the inner barrel is longitudinally movable relative to the outer barrel for recovering the inner barrel while leaving the outer barrel downhole. This relative longitudinal movement is also preferably accomplished by employing a second selectively releasable latching mechanism for selectively securing at least a portion of the inner barrel to the outer barrel. 
     In order to keep the core sample adequately cool during extraction, the coring tool in accordance with the present invention preferably comprises an inner tube having a layer of insulation disposed substantially around the inner tube and an outer shell disposed substantially around the layer of insulation. The cooling system is associated with the inner tube for cooling the inner tube and thus removing heat therefrom. Because heat may be conducted away from the inner tube the inner tube is preferably comprised of a metal material. In addition, the layer of insulation may be comprised of a foam material or an evacuated annular chamber. In order to strengthen the inner tube so that it is less susceptible to downhole hydrostatic pressures, the outer shell may be comprised of steel and/or a layer of glass or carbon fiber and epoxy. A second layer of carbon fiber and epoxy may also be disposed over the inner tube. 
     Preferably, the coring system in accordance with the present invention includes a wireline latching system for operating the coring tool. As such, a first latching mechanism interposed between the outer barrel and the inner barrel may, by wireline, selectively latch the outer barrel to the inner barrel. Moreover, a second latching mechanism interposed between the outer tube and the inner tube may be employed for selectively latching the outer tube to the inner tube. A wireline pulling tool configured to be selectively engageable with a proximal end of the inner barrel is configured to disengage the second latching mechanism and longitudinally move the inner tube relative to the outer tube. The wireline pulling tool is also configured to disengage the first latching mechanism and retrieve the inner barrel relative to said outer barrel. A second wireline pulling tool is configured to be selectively engageable with a proximal end of the inner barrel and to leave the second latching mechanism in an engaged position locking the inner tube relative to the outer tube and to disengage the first latching mechanism and retrieve the inner barrel relative to the outer barrel. 
     In operation, geological core samples are retrieved by drilling a core sample, lifting the core sample into a chamber, sealing the chamber around the core sample, retrieving the chamber and core sample contained therein while leaving an associated outer barrel and drill bit downhole, and cooling the chamber as the chamber and core sample contained therein are brought to the surface. Drilling is preferably accomplished by rotating the outer barrel assembly and a drill bit attached thereto into a subterranean formation while allowing the inner barrel assembly to remain substantially rotationally stationary relative to the formation. When drilling is complete, the chamber is unlatched from the inner barrel assembly and the chamber is lifted relative to the inner barrel assembly until the core sample is contained within the chamber. The core sample is then sealed within the chamber by closing a pressure tight valve to seal the core sample within the chamber. The core sample is then recovered by unlatching the inner barrel assembly from the outer barrel assembly and raising the inner barrel assembly to the surface. Preferably, these operations are accomplished by employing a wireline tool. 
     Once the chamber containing the core sample has been brought to the surface, a transport container is attached to the core chamber and the core sample is transferred from the core chamber to the transport container. Preferably, this transferring process is performed while maintaining the core sample under pressure. 
     In a preferred embodiment, the transport container has a distal end configured to mate with a proximal end of the pressurized core retrieval chamber and an actuable sealing device, such as a ball valve, associated with a distal end of the transport container for selectively forming a substantially pressure tight chamber within the transport container. A transferring device, such as a hydraulic telescoping piston arrangement, is also provided having a proximal end configured to mate with a distal end of the pressurized core retrieval chamber. The transferring device includes an extendable member for extending through the pressurized core chamber to force a core sample therein into the transport container. Preferably, transport container has an internal diameter substantially the same as an inside diameter of the core chamber. The transport container also preferably includes means for regulating the pressure within said transport container, such as an external or internal pressure source. 
     In operation, the core sample is transferred from a core retrieval chamber under in situ pressure by attaching a transport container to a first end of the core retrieval chamber, attaching a transferring device to a second end of the core retrieval chamber, opening the first end of the core retrieval chamber, opening the second end of the core retrieval chamber, forcing the core sample from the core retrieval chamber into the transport container with the transferring device, and sealing the transport container around the core sample. In a preferred embodiment, opening the first end comprises releasing a sealing plug from the core retrieval chamber. Thus, the plug is configured to be removable relative to the inner tube assembly such that a core sample contained within the inner tube assembly is removable through the proximal end of the inner tube assembly. In addition, it is preferable that the system be configured to allow these operations to be performed by external manipulation of the apparatus. 
     In order to more fully understand the manner in which the above-recited objects and advantages of the invention are obtained, a more particular description of the invention will be rendered by reference to the presently preferred embodiments or presently understood best mode thereof which are illustrated in the appended drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The embodiments illustrated in the following drawings are provided by way of example of the preferred embodiments of the invention and are therefore not to be considered limiting the scope of the present invention, in which: 
     FIG. 1 is a partial cross-sectional side view of a first preferred embodiment of a coring device in accordance with the present invention; 
     FIGS. 2A,  2 C,  2 D,  2 E,  2 F, and  2 G are different sections of a cross-sectional side view of a second preferred embodiment of a coring device in accordance with the present invention; 
     FIG. 2B is a cross-sectional view of the ball valve illustrated in FIG. 2A; 
     FIG. 3A is a partial cross-sectional side view of a first preferred embodiment of an insulated and cooled inner tube in accordance with the present invention; 
     FIG. 3B is a cross-sectional view of a second preferred embodiment of an insulated and cooled inner tube in accordance with the present invention; 
     FIG. 3C is a cross-sectional side view of a third preferred embodiment of an insulated and cooled inner tube in accordance with the present invention; 
     FIG. 4A is a preferred embodiment of a running tool in accordance with the present invention; 
     FIG. 4B is a preferred embodiment of an emergency release pulling tool in accordance with the present invention; 
     FIG. 4C is a preferred embodiment of a pulling tool in accordance with the present invention to be used in normal operations; 
     FIG. 5A is a cross-sectional side view of a first preferred embodiment of a transport container in accordance with the present invention; 
     FIG. 5B is a cross-sectional view of the ball valve employed in the transport container illustrated in FIG. 5A; 
     FIG. 6 is a cross-sectional side view of a preferred embodiment of a transferring device in accordance with the present invention; and 
     FIG. 7 is a cross-sectional side view of a second preferred embodiment of a transport container in accordance with the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE PRESENT INVENTION 
     Referring to FIG. 1, a coring device, generally indicated at  10 , for retrieving geological core samples generally comprises a coring bit  12  which is attached to the distal end  15  of an outer barrel  14  having a generally cylindrical configuration. With the coring tool  10  of the present invention, coring can proceed in a normal fashion. Rotary speed and bit weight will of course vary by rock formation and bit type. An inner tube  16  is retained within the outer barrel  14  and is provided with a ball valve  20  and associated ball valve operator  22  at its lower end  24 . An inner tube plug  26  is held within the inner tube  16  with retaining pins  28  and  29  and is sealed with O-ring  30  to the inner surface  32  of the inner tube  16 . The inner tube  16 , inner tube plug  26 , and ball valve  20 , when closed, define a pressure or core chamber  34  for retaining a core sample at in situ pressure when contained therein. A pressure control system  35  is connected to the inner tube plug  26  to control the pressure within the chamber  34  during recovery of a core sample. 
     The inner tube  16  is also provided with a cooling system comprised of an electronics system  36 , a power supply  38 , and coolers (not visible). The cooling system is associated with the inner tube  16  to maintain a core sample at or near in situ temperature. The inner tube  16  and outer barrel  14  are each connected to a landing sub  40 , the landing sub  40  being connected to a drill string (not shown) as is known in the art. The inner tube  16  is connected to the landing sub with a swivel device  42  which allows the inner tube  16  to remain relatively stationary with respect to the formation being drilled while the outer barrel  14 , inner barrel  48 , and bit  12  rotate. A biasing device  44 , such as a coil spring, is associated with the swivel device  42  to protect the ball valve  20  during operation. A wireline retrievable section  46 , or latch housing, is connected to the swivel device  42  and to the inner barrel  48  which extends from proximate the swivel device  42  to proximate the ball valve  20 . 
     The inner barrel  48  is provided with latching mechanisms  50  and  52 , which during the drilling operation hold the inner barrel  48  relative to the swivel mechanism  42 . In addition, latching mechanism  54  and  56  maintain the wireline retrievable section  46  relative to the landing sub  40 . The latching mechanisms  50  and  52  are employed to maintain the inner barrel  48  relative to the inner tube  16  during the drilling operation and thus the ball valve  20  in an open position. After the desired length of core has been cut from the formation, the latching mechanisms  50  and  52  are disengaged to allow the inner tube  16  to move relative to the inner barrel  48  and thus close the ball valve  20 , trapping the core sample within the chamber  34  at in situ pressure. The latching mechanisms  54  and  56  are then disengaged from the landing sub  40  so that the inner tube  16  and core sample can be tripped to the surface while leaving the outer barrel  14  and bit  12  downhole for use with an empty inner barrel assembly. 
     Referring now to FIG. 2A, a preferred embodiment of the distal end of a coring device, generally indicated at  100 , in accordance with the present invention is illustrated. The coring device  100  includes a coring bit  102  having a plurality of cutting elements  104  secured thereto positioned along the perimeter of the bit  102  for cutting into the formation. The distance between the innermost cutting elements  104 ′ define the diameter of the core that will be cut with such a bit  102 . The cutting elements  104 ′ also define an outer diameter which will cut the borehole to a size sufficient to allow the rest of the coring tool  100  to enter the borehole. The bit  102  is provided with a plurality of fluid passageways  103  in fluid communication with the space  109  defined between the outer tube  163  and the stabilizer  106 , to which nozzles  105  are attached to direct drilling fluid to the cutting elements  104 . The drilling fluid keeps the cutting elements  104  cool and moves formation chips generated by the cutting elements  104  through the junk slots  107 , which are positioned adjacent the cutting elements  104 , and back to the surface through the space provided between the coring tool  100  and the borehole. Of course, after reviewing the present invention, those skilled in the art will understand that various types and configurations of coring bits may be employed with the present invention so long as the bit can cut a core sample having an outer diameter that will fit within the coring tool  100 . The bit  102  is attached to a bit stabilizer  106  with internal threads  108  on the proximal end  110  of the bit  102  that threadedly engage with external threads  112  on the stabilizer  106 . The stabilizer  106  includes one or more stabilizing portions  114  and  116  that define a diameter substantially equal to the diameter of the borehole cut by the outermost cutters  104 ″, commonly referred to as gage cutters. The stabilizing portions  114  and  116  of the stabilizer  106  ride against the surface of the borehole during the drilling operation and help maintain the general drilling direction of the bit  102  into the formation. Basically, from an exterior view at least the distal end  118  of the coring tool  100  appears similar in configuration to other coring tools known in the art. 
     As further illustrated in FIG. 2A, the coring tool  100  further comprises one or more core catching assemblies, generally indicated at  120 . The core catchers  120  are located at the distal end  118  of the coring tool  100  and are associated with the inner tube  126 . The core catcher  120  allows the cut core to enter the inner tube  126  but prevents it from falling out while the core is being lifted to be severed from the bottom of the bore hole and when the inner tube  126  is lifted into the pressure chamber. Several types of core catchers  120  may be employed with the present invention. For example, a spring catcher  138 , basket catcher  122  and/or dog type catcher  124  may be employed. Thus, the spring catcher  138  may include a tapered cone design which expands around the core as the core enters the inner tube  126  and thus grips the sides of the core sample. Likewise, a basket type catcher  122  can be placed in the thread relief groove  128  in the back core shoe threads  130 . In addition, an upper shoe  132  can be used with or replaced by a dog type catcher assembly  124  which employs a plurality of core catching members such as core catching members  134  and  136  that fully open to allow the core to enter therethrough but close to pierce soft or unconsolidated material and thus substantially close the tube preventing the core from falling out of the tube. 
     With specific reference to the spring catcher  138  associated with the distal end  118  of the coring tool  100 , the spring catcher  138  comprises a split tapered ring  140  that is actuatable to essentially grab the sides of a cut core sample in order to lift the core sample from the bottom and sever the core sample near the bottom of the borehole. The spring catcher  138  is actuated by the lower shoe  144  having an inwardly tapered inner surface  145  such that as the spring catcher  138  is forced toward the bottom of the borehole by the weight of the core sample being lifted. Thus, the spring catcher  138  is pressed against the core sample. The spring catcher  138  further includes a plurality of straight or helically-configured grooves  146  to provide a better surface for grasping the core sample and also to allow drilling fluid to flow between the core sample and the spring catcher  138  so as to equalize the pressure of drilling fluid contained within the coring tool  100  and that at the bottom of the bore hole and to allow drilling fluid in the inner tube  126  to escape as the core enters. A stop ring  150  is provided above and adjacent to the spring catcher  138  so as to prevent the spring catcher  138  from moving up into the spring catcher  120  and inner tube  126 . 
     As will be described in more detail, the coring tool  100  of the present invention is configured such that the outermost members, such as the stabilizer  106  and bit  102  shown in FIG. 2A, rotate in order to drill the borehole while the inner members such as the inner tube  126  and core catcher  120  substantially maintain their rotational orientation during the drilling process. Accordingly, an outer shoe  152  rotates with the bit  102  and is provided with a lower bearing  154  which allows rotation of the bit  102  relative to the inner tube  126  while maintaining the rotational orientation of the core catcher  120 , core lifter  138 , inner tube  126  and associated components. As such, the inner tube  126  does not generate heat from friction as would be the case if the inner tube  126  rotated relative to the cut core sample. When recovering core samples that may be in a partially frozen state, such heating would prove detrimental to recovery of such core samples as substantial temperature variations may cause the core sample to destabilize. 
     The coring tool  100  also includes an externally or remotely released or actuable sealing device such as a ball valve assembly, generally indicated at  160 , positioned proximate the distal end  118  of the coring tool  100  and above the core catcher  120 . The ball valve  160  is provided within the coring tool  100  to be closed once the core sample has passed therethrough to trap the core sample at in situ pressure. When extracting core samples containing methane hydrates, it is preferable to maintain the core sample at a pressure as close to the downhole pressure as possible in order to maintain the physical and chemical properties of the core sample. 
     As shown in FIGS. 2A and 2B, the ball valve assembly  160  is comprised a ball  162  having a bore  164  extending therethrough, the bore  164  having a diameter sufficient to allow passage therethrough of the distal end of the inner tube  126  and the core catcher  120 . The ball  162  is pivotally attached to a ball valve housing  166  with a pivot pin  168  and thrust washer  170  in which to allow rotation of the ball  162  relative to the ball valve housing  166 . 
     The ball  162  of the ball valve  160  is actuated with one or more pivotally attached elongate members or links  172 . The link  172  is attached at a first end  174  with a link pin  176  and at a second end  178 . The link  172  is preferably controlled by axial motion between the outer tube  163 , which is preferably threadedly connected to the operator housing  185 , and the inner tube  126 . As will be described in more detail, a ball valve latch assembly located at the proximal end of the coring tool  100  controls movement of the ball valve operator  184 . Once the latch is released, continued pull on a wireline tool causes the inner tube  126  to retract upward through the ball  162  until a catch mechanism such as a protrusion or upset  180  on the inner tube  126  contacts a shoulder  182  in the operator  184 . The operator  184  moves upward along with the inner tube  126  and pulls on the link(s)  172  rotating the ball  162  to a closed position. The spacing between the upset  180  and the shoulder  182  ensures that the ball  162  does not begin to rotate closed until the inner tube  126 , core catchers  120 , and core sample have completely passed through the bore  164  defined by the ball  162 . Preferably, the shoulders  182  are precisely machined to ensure that rotation of the ball  162  is accurately controlled in both the fully open and fully closed position. In a preferred embodiment, the required stroke for complete ball valve rotation from a fully open position to a fully closed position is approximately 1.75 in. (44.45 mm). In addition, by knowing the distance from the top edge  186  of the ball  162  when the ball is in a fully closed position to the distal end  119  of the inner tube  126 , the distance between the upset  180  and the shoulder  182  can be configured to ensure that a core sample is fully retracted through the ball  162  before the ball  162  is actuated to a closed position. In a preferred embodiment, the distance from the top  186  of the ball  162  when in a closed position to the distal end  119  of the inner tube  126  is approximately 15.8 in (401 mm). Extra travel of the upset  180  relative to the shoulder  182  may be desired to make sure that if a small portion of the core is hanging past the catcher  120 , the portion of the core will not jam the ball valve  160  as it is rotated to a closed position. Therefore, a stroke length of 17 in. (432 mm) may be selected before rotating the ball valve  160  to the closed position. Accordingly, a total stroke length of 19 in. (482.6 mm) may be provided for the lower section of the inner tube  126  to retract the core completely through the ball  162  and completely close the ball valve  160 . 
     The link  172  is pivotally linked at its second end  178  with a link pin  190  to a spring carrier member  194 . A threaded fastener  192 , such as a socket head shoulder screw, is secured to the distal end  196  of the operator  184 . An operator biasing member  198 , such as a coil spring, is interposed between the head  200  of the fastener  192  and the distal end  196  of the operator  184 . The operator spring  198  may be provided with a nominal 0.25 in. (6.35 mm) travel to accommodate variations in length tolerances in the parts and while maintaining complete ball  162  closure. In addition, the operator spring  198  may provide resistance to damage of the inner tube  126 . Thus, in order to prevent damage that may otherwise occur when trapped pressure in the inner tube  126  forces the inner tube shoulder  270  into the seal sub  280 , small springs  198  are provided in the ball valve operator  184 , which allow it to extend to reduce the resulting high stress on these components. Accordingly, the shoulders  223  near the seal  216  can engage. Thus, the force produced by the preloaded springs  198  is transmitted to these components and all of the high forces are contained within the seal carrier  214 . Shoulder screws  197  are used to preload the springs  198  and limit their travel and at the same time hold the assembly together. The springs  198  are preferably arranged in an asymmetrical annular pattern which produces a force that balances the force generated by the eccentric location of the links  172 . 
     The ball valve operator  184  is provided with a collet  202  at its upper end  204  which enables assembly by simply sliding the ball valve operator  184  over the bonded sleeve  206  on the inner tube  126 . A disassembly tool (not shown) is available which opens the collet  202  to allow disassembly. The ball valve operator  184  is also provided with flats  207  (not shown) on its sides to match the ball  162 . These flats fit into the non-circular inner surface  240  of the ball valve housing  166 . This matching or keying prevents unwanted rotation of the parts relative to each other and also traps the links  172  on the link pins  168  without the need for any other type of retaining devices. 
     The ball valve  160  is held on one side within the coring tool  100  with a sealing sub  210  which, at a distal end  212  fits within the outer shoe  152  and is sealed relative to and fits within the ball valve housing  166  at the proximal end  213  of the sealing sub  210 . A ball valve seat  214  fits within the proximal end  213  of the sealing sub  210 . A ball valve sealing retainer  216  having a lip  218  thereon retains a ball valve seal  220  between the sealing sub  210  and the ball valve seat  214 . The ball valve seal  220  includes a sealing surface  222  which contacts and forms a seal with the outer surface  224  of the ball  162 . The configuration of the ball valve seal  220  and more specifically of the position of the sealing surface  222  between the ball valve seat  214  and the ball  162  promotes a tighter seal between the ball  162  and the seal  220  as the pressure differential between the pressure within the pressure chamber  234  and ambient pressure increases. In effect, the portion of the seal  220  becomes wedged between the ball  162  and the ball valve seat  214 . Sealing of the ball  162  with the seal  220  is further enhanced by allowing the ball  162  to float within groove  151 . Preferably, the seal  220  is comprised of a resilient material, such as a rubber compound, that is also resistant to abrasion and thus damage that may otherwise occur from movement of the ball  162  relative thereto. In addition, because the coring tool  100  includes structures to seal the core sample at in situ pressure, other sealing devices may be employed to seal the components defining the pressurized chamber relative to one another. For example, o-ring  228  positioned between the ball valve housing  166  and the sealing sub  210 , o-ring  230  positioned between the sealing sub  210  and the valve seat  214 , o-ring  232  interposed between the ball valve housing  166  and the operator housing  185 , and o-ring  233  positioned between and sealing the operator housing  185  to the outer tube  163  are each provided to seal the various components forming the ball valve assembly  160  relative to the rest of the coring tool  100  to form a substantially air tight core chamber  234 . 
     As specifically shown in FIG. 2B, the ball valve housing  166  has a portion  240  of the inside surface  242  milled to a non-circular cross-section. This provides a thicker wall  244  with sufficient thickness for pivot pins  168  and  169  which are inserted into holes  246  drilled into the thicker walls  244  of the ball valve housing  166 . The pivot pins  168  and  169  are provided with o-ring seals  248  and  249  on their outer diameter to seal in pressure while allowing rotation. The washers  170  and  171 , preferably made from glass-filled Teflon, act as thrust bearings and thus provide a low friction surface for easier manual ball valve  160  operation when a high pressure differential exists across the pivot pins  168  and  169 . It is preferable that at least one of the pivot pins  168  and  169  is provided with a key on one end which engages a slot in the ball  162  and further includes a hex socket  250  in the end thereof that faces to the outside of the ball valve housing  166 . Accordingly, if necessary, the ball  162  can be manually opened or closed from outside the ball valve housing  166  by placing a hex key in the socket  250  of the pivot pin  169  and rotating the hex key until the ball  162  is in the desired position. Of course, if each pivot pin  168  and  169  were provided with sockets  250 , two hex keys could be employed and simultaneously rotated to operate the ball  162 . It is also preferable, for safety reasons, that the pivot pins  168  and  169  be secured relative to the ball valve housing  166  such that the pivot pins  168  and  169  cannot be ejected or blown out from the ball valve housing  166  by internal pressure. Accordingly, the pivot pins  168  and  169  are installed from the inside of the ball valve housing  166  prior to installing the ball  162  and thus abut against the inside  242  of the ball valve housing  166 . The pivot pins  168  and  169  are thus prevented from blowing out by the solid wall  244  of the housing  166  itself rather than by threads, snap rings or other such devices and structures. 
     Referring now to FIG. 2C, the stabilizer  106  is attached, as with internal threads  260 , to the outer barrel  262  which preferably includes an externally threaded portion  264  configured to match and engage with the internal threads  260  on the stabilizer  106 . As shown in this section of the coring tool  100 , encased within the outer barrel  262  is the outer tube  163 , the inner tube  126  and insulative sleeve  206 . Disposed on and attached to the outside surface  266  of the sleeve  206  is an inner tube lifting sleeve  268  which includes a lip or upset  270 . As will be further described with reference to FIG. 2D, this upset  270  is positioned at a location relative to the inner tube  126  such that the upset  270  will engage with a shoulder  281  of a seal sub  280  attached to the outer tube  163  after the inner tube  126  and a core sample contained therein has cleared the ball valve  160  illustrated in FIG.  2 A. Thus, once the sleeve  268  engages with the outer tube  163 , continued lifting of the inner tube  126  will result in lifting of the outer tube  163  and structure attached thereto such as the ball valve  160 . In addition, because at this point the ball valve  160  will preferably be in a closed position, the core sample is now being lifted at in situ pressure. The sleeve  268  is also provided with annular grooves  272  and  274  on its outer surface  276  to provide a sealing surface thereon. O-rings or polypak seals may be inserted into the annular grooves  272  and  274  for providing seals when the outer surface  276  contacts the upper seal sub  280  illustrated in FIG.  2 D. 
     In FIG. 2D, the outer barrel  262  shown in FIG. 2C houses the upper seal sub  280  which is preferably threadedly engaged with and joined to and between the lower outer tube  163  and the middle outer tube section  282 . Likewise, an inner seal member  284  having o-ring  286  seals the inner tube  126  to the thermal electric cooling (TEC) system assembly, generally indicated at  288 . The TEC system  288  is employed to substantially maintain the temperature of the core while it is in transit from the bottom of the borehole to the surface and thus help prevent degradation of the core sample during the tripping operation. Preferably, the inner tube  126  is comprised of a thermally conductive material such as aluminum or another metal or a metal alloy, and is connected to a series of thermal electric coolers  290 . These coolers  290  are preferably powered by a rechargeable battery pack located higher up in the tool. 
     As shown in more detail in FIG. 3A, the inner tube  126  is provided with insulation  300  surrounded by filament wound composite layers  302  and  304  to prevent hydrostatic pressure from collapsing the insulation  300 . Preferably, the insulation is comprised of a foam material. It is also contemplated that the layers  302  and  304  may be comprised of metal and that the insulation  300  may be omitted such that the mere existence of a space such as an evacuated chamber defined between the layers  302  and  304  provides sufficient insulation just as an insulation effect is achieved with a Thermos® bottle. 
     An interface sleeve  306  is attached at its distal end  307  to the inner tube  126  as with a TIG weld  308 . The proximal end  310  of the interface sleeve  306  is attached to a TEC carrier or holder  312 . The TEC holder  312  is preferably comprised of beryllium copper and is faceted for securing the thermoelectric cooling elements  290  thereto. A TEC cover  314  is attached to the outside surface  316  as with a structural bond  318 . The steel cover  314  in combination with the TEC holder  312  provides a protected chamber  318  for housing the TEC elements and their associated electronics. The TEC holder  312  is preferably threadedly connected to the interface sleeve  306 . In addition, the interface sleeve  306  may include an annular groove  319  for housing an o-ring to seal the interface sleeve  306  to the TEC holder. Wires  320  extend from the TEC elements  290  to the TEC control electronics and battery supply, described in more detail below. 
     Preferably, the TECs  290  consist of several solid state devices which utilize the Peltier effect of transistors, i.e., electrical current through a transistor to create a temperature difference across the transistor. The TEC&#39;s  290 , such as that manufactured by Melcor Corp., cold side  322  is preferably mounted to the holder  312  using a copper-filled or aluminum oxide epoxy for high conductivity. In addition, precision machined copper blocks  324  are mounted, with the same adhesive, to the hot side of each TEC  290 . These blocks  324  preferably match the curvature of the sleeve  314  enclosing the TECs  290  and thus fit closely against the inside surface  326  so that thermally conductive grease positioned between the blocks  324  and the sleeve  314  create a thermal path to the outer tube. 
     In another preferred embodiment illustrated in FIG. 3B, the inner tube  700  is comprised of steel and is surrounded by a plurality of heat pipes  702 . The heat pipes  702  are mounted directly to the inner tube  700  with an adhesive  704  such as an epoxy. Preferably, the core catcher connecting threads (see FIG. 2A) are machined directly into the inner tube  700  eliminating at least one component from the embodiment described in FIG.  2 A. Similarly, the upper end may include a threaded connection integrated into the inner tube  700 . The heat pipes  702  are surrounded by a foam layer  706  covered by an outer shell  708  preferably comprised of a filament wound epoxy filled carbon. To ensure adequate transfer of thrust loads imposed by captured pressure within the inner tube  700 , the heat pipes  702  may be shortened such that they do not extend over the threaded connection. As such, an adequate safety factor in the bonding between the outer composite layer and the rest of the inner tube  700  is provided. Moreover, the adhesive is selected to have a high shear strength for safe load transfer. It may also be desirable to provide a thin carbon fiber and epoxy composite layer  710 , or some other high tensile strength layer, between the heat pipes  702  and the foam layer  706  to protect the heat pipes from compressive loads that may otherwise be imposed on the heat pipes due to external (hydrostatic) pressure. Such a layer  710  may lower stresses on the relatively weak heat pipes, which are preferably comprised of copper, and keep them from collapsing. While the illustration in FIG. 3B, shows the heat pipes  702  being contoured to fit about the inner tube  700 , the contoured heat pipes  702  may be replaced with a larger number of more circularly configured heat pipes of smaller cross-sectional size. 
     As shown in FIG. 3C, to maximize heat transfer across the threaded connection between the inner tube  712  and the TEC carrier  714 , heat pipes  716  are incorporated into the TEC carrier  714 . The heat pipes  716  extend from the shoulder  719  at the threaded end  720  to the distal end of the TECs  718 . As illustrated, the heat pipes  722  are mounted in the carrier wall to minimize the distance heat must flow from the heat pipes  722  to the TECs  718 . In addition the composite inner tube  724  is attached to the TEC carrier  714  such that the heat pipes  722  extend over the TEC heat pipes  716  resulting in an efficient means of carrying heat from the inner tube  724  to the TEC carrier  714 . Preferably, the heat pipes will be partially evacuated and filled with a coolant such as a methanol chloride solution. The coolant is circulated through the heat pipes  722  by evaporation and condensation that will occur within the heat pipes  722  as various portions of each heat pipe are exposed to different temperatures. It is also contemplated that the coolant could be circulated using mechanical means such as a pump. A wicking material may also be included which is comprised of copper mesh. The heat pipes  722  preferably operate over a temperature range of −10 to 30 degrees centigrade. 
     Referring again to FIG. 2D, electronics, collectively referenced at  330 , to control the function of the TECs  290  are placed adjacent to the TEC elements  290  within a pressure tight chamber  332 . The electronics carrier  334  also forms a part of the inner tube  126 . 
     Preferably, the temperature control system  288  consists of current regulators, switches for the coolers, a comparator, a temperature sensor, and a means for setting the temperature at any of a number of different temperatures. These components may be mounted on one or more printed circuit boards and housed in the same chamber  336  as the TECs  290  and/or in the electronics chamber  338 . The TECs  290  may be switched on/off to regulate the temperature that is selected on a multi-position switch. 
     Wires or cables  350  connected through the high pressure bulkhead connectors  352  carry the power from a battery pack (as will be described in more detail) to the TECs  290 . Preferably, the cables  350  comprise molded cable assemblies to ensure reliability. The cables  350  travel along the space  351  defined between the outer tube section  353  and the pressure barrel  414 . Preferably, the cables  350  are secured to the outside surface  415  of the pressure barrel with bands or other retaining mechanisms or structures. As with other components described herein, o-rings  354 ,  355 ,  356 ,  357 ,  358 ,  361  and  363  are provided to seal the various components of the cooling system  288  to produce a sealed core retrieval chamber  360 . 
     At the proximal end  362  of the cooling system  288 , a sealing device or member such as an inner tube plug  364  is secured thereto to form the proximal end of the chamber  360 . The plug  364  is secured to the proximal end  362  of the electronics carrier  334  with a sleeve  366  which extends over the TECs  290  and is coupled to the inner tube  126  with coupling  368  and split rings  370  and  372 . The plug  364  is secured to the sleeve  366  by a plurality of pins  374  which are preferably threadedly engaged into a plurality of holes  376  provided in the outer surface  378  of the plug  364 . Because the plug  364  is made to be removable from the inner tube  126 , as is desired to remove a pressurized core from the chamber  360  when the inner barrel  48  is retrieved to the surface, the pins  374  may be unscrewed to a point where the distal end of the pin  374  no longer engages with the hole  376  in the plug  364 . When each pin  374  is sufficiently disengaged, the plug  364  may be removed from the inner tube  126 . 
     In addition, because the chamber  360  may be under high pressure when the pins  374  are removed, a safety nut  380  which is threadedly engaged with the sleeve  366  retains the plug  364  relative to the sleeve  366  as the pins  374  are removed or at least partially extracted. The plug  364  is also provided with a burst disk assembly, generally indicated at  381 , comprising a burst disk holder  382 , a burst disk ring  384 , and a burst disk  386 . The burst disk assembly  381  is in communication with a passageway  390  which is in fluid communication with the chamber  360 . The passageway  390  may be comprised of an internal bore extending from the distal end of the plug  364  to various pressure sensors and valves. For example, a pressure transducer  392  having a pressure cap  393  is in fluid communication with the passageway  390  to measure the pressure within the chamber  360 . The pressure transducer  392  may provide pressure data during the drilling operation, as the core is being tripped to the surface, and when the inner barrel  342  is at the surface. Accordingly, constant pressure monitoring can occur to ensure that the inner barrel  342  does not become pressurized over a maximum internal pressure. In addition, several valves  394  and  396 , such as valves commonly referred to as bullet valves, are positioned within the plug  364  and in communication with the passageway  390  such that the pressure within the chamber  360  can be controlled. For example, by attaching one or more of the valves  394  and  396  to a pressure source, the pressure within the chamber  360  can be increased. Likewise, by opening one or more of the valves  394  and  396 , the pressure within the chamber  360  may be decreased or fluid samples obtained. 
     Of course, the various pressure components should be sealed relative to the chamber  360  so that they maintain a relatively constant pressure within the chamber  360 . Such sealing may be accomplished with o-rings  398 ,  399 , and  400 , gaskets, or other sealing structures and members known in the art. 
     The burst disk  381  is incorporated into the pressure section to protect the equipment and operators from possible over-pressure and resulting bursting of the inner barrel  342 . The burst disk assembly  381  is calibrated quite accurately to release the pressure from the chamber  360  preferably at a pressure of 4000 psi. A pressure tolerance of 4000 psi allows for slight over pressure of the inner barrel  342  during core transfer, etc. without bursting and still falls well within the safe design range of the inner barrel assembly  342 . 
     An accumulator end sub  410  is attached to the proximal end  412  of the plug  364  and sealed thereto with o-ring  400 . The sub  410  includes a bullet valve  394  which is sealed to the sub  410  with o-ring  401 . The valve  394  is provided in communication with the passageway  417  extending through the sub  410 . The sub  410  is attached to the accumulator barrel  414  and sealed thereto with o-ring  402 . Preferably, the pressure barrel  414  defines a pressure chamber  416  which is typically pressurized to a pressure that will predictably be at least as high as the in situ pressure experienced downhole. The valve  394  is utilized to bleed off pressurized gas from within the chamber  360  when disassembling the pressure barrel  414  from the plug  364 . In addition, pressurized fluid within the chamber  360  can be bled off or sampled by opening the valve  396 , which is normally in a closed position when downhole. The pressure within the pressure chamber  416  is equalized with the pressure in chamber  360  by opening the valve  395  which will allow liquid and/or gas within the chamber  360  to flow through the passageways  390 ,  413  and  417  to the pressure chamber  416 . 
     The purpose of the pressure section is to first, provide some measure of protection from rapid pressure fluctuations due to thermal changes and/or slow leakage. Second, the pressure section provides for safe release of pressure in the unlikely event that the barrel traps pressure downhole or produces pressures above specified allowables. The pressure section also contains a pressure transducer to check the system pressure after the barrel is brought to the surface. In addition, the pressure control section is equipped with externally operable shut-off valves, such as valve  394 , and access ports to allow for isolating the two sections and for bleeding off pressure before disconnecting them. These same access ports also provide for sampling core fluids if desired. 
     Referring now to FIG. 2E, a gas accumulator generally referred to at  420 , is incorporated into the coring tool  100 . The gas accumulator  420  includes a piston  422  slidable within the pressure chamber  416 . An o-ring groove  424  is provided to house an o-ring for sealing the piston  422  to the inside surface  426  of the pressure barrel  414 . The piston  422  also separates pressurized gas contained between an accumulator fill sub  428  and core fluids contained in the pressure chamber  416 . The accumulator fill sub  428  includes a valve  430  in communication with a passageway extending from the valve  430  to the distal end  432  of the fill sub  428 . The distal end  432  of the fill sub  428  is sealed to the pressure barrel  414  with an o-ring  434 . The accumulator fill sub  428  is also provided with a passageway or exit port  452  through which the cable  350  shown in FIG. 2D may connect to a battery pack  442 . In operation, the chamber  436  is charged with a high pressure gas, such as nitrogen, prior to the tool  100  running in the hole. Preferably, the charge is about half of the expected bottom hole pressure, but may be adjusted for different pressure/leakage characteristics if desired. As the tool  100  is lowered into the hole, the increasing bottom hole pressure forces the piston  422  toward the proximal end  438  of the pressure barrel  414  compressing the gas until equilibrium is reached. Preferably, this equilibrium is such that as the barrel  414  reaches the borehole bottom, the chamber  436  is approximately equal in size to the size of the pressure chamber  416  and thus the piston  422  is positioned approximately halfway between the fill sub  428  and the accumulator end sub  410 . 
     As previously described, the ball valve  160  shown in FIG. 2A is preferably closed to seal the core sample at bottom hole or in situ pressure. As the core sample is brought to the surface, any leakage or volume changes due to temperature or pressure variations may be partially compensated for by the pressurized gas in the chamber  436 . After viewing the present invention, those skilled in the art will appreciate that the pressure response of the system is proportional to the chamber volume and initial pressure and is therefore easily modeled. Preferably, the pressure chamber  436  is sized so that a leakage of 1 cu in. (16.4 ml) per minute therefrom for thirty minutes would result in a loss of only half of the pressure contained with in the pressure chamber  436 . For methane hydrates, a loss of half of the pressure from the chamber  436  as described would still substantially preserve the integrity of the core sample as methane hydrates typically do not begin to decompose and give off large quantities of gas until pressures are reduced to approximately 500 psi (34 bar). Assuming that no significant leakage of the pressure chamber  436  occurs between coring runs, the chamber  436  typically should not have to be recharged between each coring run. 
     As further illustrated in FIG. 2E, a battery barrel  440  is attached to and sealed as with o-ring  443 . The battery barrel  440  houses the battery pack  442  that provides electric power to the electronics  330  and the TECs  290  shown in FIG.  2 D. The battery pack  442  preferably comprises a plurality of rechargeable cells with an external means of switching the batteries on and off. Preferably, the battery pack  442  can provide for one hour of continuous full power cooling. 
     Because the outer tube  353  moves with respect to the battery barrel  440  as the ball valve  160  (see FIG. 2A) is actuated, the battery barrel  440  is attached to a magnet sub  444 , which trips a switch  446  that is attached to the accumulator fill sub  428  with retaining ring  448  and sealed thereto with o-ring  450 . The magnet sub  444  is comprised of a coupling  445  which attaches the outer tube portion  353  to the outer barrel portion  447  and a magnet  449  attached thereto facing the battery barrel  440 . This magnetic sensing switch, commonly referred to as a Hall effect sensor, turns on the power to the electronics  288  (see FIG. 2D) as the ball valve  160  (see FIG. 2A) is closed prior to the inner barrel, generally indicated at  342 , being tripped to the surface. For example, during the ball valve  160  closure process, the Hall effect sensor  446  in the sub  428  positioned just below the battery pack  442  moves into the magnet sub  444  and thus magnetically trips the Hall effect switch  446 . Of course, those skilled in the art will appreciate after reviewing the present invention that other switching devices and mechanisms whether electronic or mechanical or a combination thereof may be employed to selectively activate the battery pack  442 . 
     The use of a Hall effect switch  446  and other electronics may draw power from the battery pack  442  at all times. Thus, it may be desirable to employ other types of switching mechanisms that would further limit the power draw on the battery pack  442  when the batteries are not being utilized to provide power to the TECs  290 . In addition, it may be desirable to remove the battery pack  442  from the battery barrel tool  100  during extended periods of storage or to exchange it quickly with a fully recharged battery pack  442 . 
     As further illustrated in FIG. 2F, the battery barrel  440  is attached to a battery end cap  460  and sealed thereto with o-ring  462 . Because it is desirable to allow adjustment of the core shoe  144  (see FIG. 2A) relative to the bit  102 , the battery end cap  460  is provided with a threaded bore  464  at its proximal end  468  for adjusting the inner tube, and thus the core catcher relative to the outer tube. An elongate shaft or bearing mandrel  470  having an externally threaded portion  472  is secured to the end cap  460 . In addition, a bearing locknut  474  is threaded onto the mandrel  470  and abutted against the end cap  460  to ensure that the mandrel  470  does not easily unscrew from the end cap  460 . In order to tighten the end cap  460  relative to the locknut  474 , each are provided with keyways or bores  476 - 479  to which tools (not shown) may be attached to rotate the components relative to one another. 
     The mandrel  470  is provided with at least one transversely extending protrusion or retaining portion  480  proximate its proximal end  482 . Bearings  484  and  485  are secured about the retaining portion  480  to allow the proximal end  482  of the mandrel  470  to slide relative to the bearing housing  486 . The bearing  485  is held relative to the retaining portion  480  with a retaining ring  487  which abuts the bearing  485  and is secured within an annular groove provided in the mandrel  470 . The bearing housing  486  extends along a substantial length of the mandrel  470  and is secured relative thereto at the distal end  488  of the bearing housing  486  with a bearing seal sub  490 . An oil seal  492  which is held relative to the bearing seal sub  490  with a retaining ring  494  helps prevent oil, grease, or other lubricants contained within the bearing housing  486  from escaping as the mandrel  470  actuates. A grease fitting  495  and pipe plug are provided to supply lubricants to the bearing and mandrel assembly. In the space  496  defined between the mandrel  470  and the bearing housing  486 , a biasing device, such as a coil spring  498  is positioned to force the bearing  484  from the seal bearing  490 . Thus, the mandrel  470  is biased relative to the ball valve latch housing  500 . 
     Compensating piston  491  and associated sealing member  493  provides pressure balancing of the oil or grease contained within the bearing housing  486 , with the mud pressure external to the oil seal  492 . This pressure balancing extends the life of the oil seal  492 , reduces friction associated with the rotating oil seal  492 , and reduces the tendency of the inner tube to rotate with the outer tube and outer barrel. 
     In addition to longitudinal movement of the lower inner barrel assemblies  518  relative to the latching mechanisms at the upper portion of the tool  100 , the mandrel  470  while being fixed relative to the battery end cap, is free to rotate relative to the bearing housing  486 . Accordingly, the bearing housing  486  and mandrel  470  assembly provides a swivelling mechanism, generally indicated at  481 , which allows the inner barrel  518  of the coring tool  100  to stay relatively stationary as the outer barrel  262  rotates to rotate the coring bit  102  into the formation. 
     A swivel mechanism  481  provides for free rotation of the outer barrel  262  relative to the inner tube  126  so that the inner tube and core catchers  120  do not rotate and damage the core. The swivel mechanism also provides a low friction connection for both axial and radial loads. In the axial direction, the swivel mechanism  481  provides free rotation in the case of either up or down thrust of the inner tube  126 . Normally the inner tube  126  hangs from the swivel mechanism  481 . However, it is possible for the inner tube  126  to develop upward thrust should the core have difficulty entering the core catcher or become jammed in the inner tube  126 . Core jamming can produce axial forces on the swivel mechanism  481  equal to the applied weight on bit and is the usual cause of swivel mechanism  481  failure. In the radial direction, the swivel mechanism  481  prevents the top end of the inner tube  126  from rotating against the outer tube  353 . This is especially true in high angle holes. The swivel mechanism is located just below the ball valve latch assembly  510 . The bottom of the inner tube  126  is guided radially by an ultra-high molecular weight polyurethane journal bearing installed in the ball valve end sub  160 , which provides a low friction bearing for the lower end of the inner barrel assembly  518 . This material is highly abrasion resistant and provides an extremely low coefficient of friction. Area for mud flow between the outer tube  353  of the inner barrel assembly  518  and bit is provided for by axial grooves or scallops in the inner diameter of the coring bit  102 . 
     The oil sealed thrust bearings  485  and  484  (one for up thrust and one for down thrust) are incorporated into the swivel mechanism  481 . The ball valve protection spring  498  is also contained in the swivel mechanism to better protect it from axial loads. The spring  498  is preloaded sufficiently to provide enough force to lift the battery section  441 , pressure section  342  and inner tube  126  with the core in addition to closing the ball valve  160 . 
     The biasing feature of the mandrel  470  and spring  498  arrangement is primarily provided to prevent overpull or damage to the ball valve components  160  shown in FIG. 2A, such as when full wireline pull is placed on the ball valve links  172  and link pins  190 , as may be the case if the ball valve  160  jams in a fully or partially open condition or if the ball valve operator  184  does not reach the stop shoulder, resulting for example from a piece of the core protruding out the inner tube and core catchers. The ball valve mechanism  160  is thus protected by the ball valve protection spring  498  which is preferably part of the swivel mechanism  481  located between the latch section and the battery section  441 . Locating the spring  498  above the inner tube  126  as previously discussed requires that it be strong enough to lift all of the weight of the battery section  441 , pressure section  342 , core, and inner tube assembly, generally indicated at  127 , in addition to the desired controlled closing force. 
     As further illustrated in FIGS. 2F and 2G, the proximal end  502  of the bearing housing  486  is preferably threadedly secured to the ball valve latch housing  500 . The latching system illustrated in FIGS. 2F and 2G shows two positions of the latches, the lower half of the figures illustrating the position of the latches when the coring tool  100  is actively drilling into the formation and the upper half of the figures illustrating the position of the latches when the core sample is being retrieved while leaving the outer barrel and drill bit downhole. 
     As has been previously discussed, the coring tool  100  preferably employs a series of latches that work together to operate the coring tool  100  using a single wireline (not shown). Two latch assemblies  510  and  512  are provided to operate the coring tool  100 . Thus, upper inner barrel latch locks or latch dogs  512  secure the inner barrel assembly  518  to the outer barrel assembly  514  while the coring operation is in progress and must be released to allow the inner barrel assembly  518  to come out of the hole while leaving the outer barrel assembly  514  downhole. The lower ball valve latch assembly  510  controls the operation of the ball valve  160  as previously described by allowing the inner tube assembly  516  to move relative to the outer tube assembly, generally indicated at  129 . When the latch mechanisms  510  and  512  are in the position shown in the lower half of FIGS. 2F and 2G, the latch member  521  resides in a recess  590  provided in the inner surface of the landing sub  586 . Likewise the latch member  511  mates with a recess  513  formed in the inner barrel latch housing  515 . In this position, an inner barrel latch spring  592 , which is retained between the inner barrel latch piston  594  and the inner barrel latch spring retainer  581 , and a ball valve latch spring  593 , which is retained between the ball valve latch piston  600  and a ball valve spring retainer  601 , are in an expanded state with a portion  599  of the inner barrel latch piston  594  abutted against the inner barrel latch housing  515 . Likewise, the ball valve latch piston  600  abuts against the ball valve latch housing  500 . In this position, the latch member  521  is not engaged with the inner barrel latch piston  594 , and the latch member  602  is not engaged with the ball valve latch piston  600 . 
     Conversely, when the latch mechanisms  510  and  512  are in the position shown in the upper half of FIGS. 2F and 2G, the latch member  520  resides in a recess  604  provided in the piston  594  and the latch member  608  mates with recess  610  formed in the ball valve piston  600 . In this position, the inner barrel latch spring  592  and the ball valve latch spring  593  are in a compressed state such that when the latch members  520  and  608  disengage from their respective pistons  594  and  600 , the pistons  594  and  600  are forced to a position where the latch members  520  and  608  cannot mate therewith. In this position, the latch member  521  is not engaged with the landing sub  586  and the latch member  608  is not engaged with the inner barrel latch housing  515 . Accordingly, the inner barrel assembly  518  can be recovered while leaving the outer barrel  514  and drill bit  102  downhole. 
     As shown in FIGS. 4A-4C, the system preferably utilizes modified Camco PRS pulling tools for setting and retrieving the inner barrel assembly  518 . A running tool  550  is comprised of a fishing neck  551  attached to a mandrel  552  and having a shear pin  554  interposed thereinbetween. A ratcheting system is comprised of a ratchet housing  556  and a ratchet sleeve  558  positioned to engage with teeth  560  provided on the outside of the mandrel  552 . A shear pin  562  retained by a shear pin sleeve  564  secures the mandrel  552  to the spring housing  564 . The spring housing  564  contains a coil spring  566  which is interposed between the spring housing  564  and the collet base  568 . The collet base  568  is secured relative to the mandrel  552  with a collet housing  570 . The collet body  574  is secured to the collet base  568  and is partially housed by a housing extension  572 . The collet body extends to the collet core  576  which is secured to the distal end of the mandrel  552 . The collet body  574  is provided with a plurality of upsets such as upsets  578  and  579  to engage with an inner barrel latch collet  580  formed into the inner barrel latch spring retainer  581  shown in FIG.  2 G. Thus, as shown by the arrows, when the running tool  550  is inserted into the inner barrel latch collet  580 , the upsets  578  and  579  are forced away from the end portion  582  as indicated by the arrow  581  to a position where they can bend or flex as indicated by arrows  583 . In addition, the collet  580  is comprised of a plurality of finger-like projections  585  having protrusions  587  thereon for grasping the upsets  578  and  579  to hold the collet body  574  relative to the tool  100  when the projections  585  are in the position shown in the upper half of FIG.  2 G. The projections  585  expand to release the collet body  574  when in the position shown in the lower half of FIG.  2 G. As such, prior to running the inner barrel  518  into the borehole, the inner barrel  518  may be hung from the running tool  550 . Inserting a threaded bolt (not shown) into the threaded bore  589  prevents the piston  594  from moving to the position shown in the lower half of FIG.  2 G. Such a bolt is removed prior to running the inner barrel  518  downhole. Thus, when the end portion  582  on the collet core  576  engages with the piston shoulder  634  formed into and defined by the inner barrel latch piston  594 , the collet  580  moves to the position shown in the lower half of FIG. 2G, automatically releasing the running tool  550 . As such, the latch members  520  and  521  engage the outer barrel  514 . Accordingly, when the running tool  550  releases, the operator knows that the latches  520  and  521  have engaged and the tool  100  is ready for drilling. 
     The shear pins  554  and  562  are not used in normal operation but are provided in the case of failure of the latching system. Of course, those skilled in the art will appreciate after understanding the present invention that other drilling accessory equipment such as jars, weights, over shots, etc., along with a wireline unit will be employed with the present invention. The coring tool  100  is designed such that the spacing between the landing shoulder  584  and collet shoulder  582  effects the operation of the latches and thus the operation of the coring tool  100 . For example, the running tool  550  illustrated in FIG. 4A is configured to engage with the inner barrel latch collet shown in FIG. 2G when the tool  100  reaches the bore hole bottom and thus while the tool  100  is being employed for drilling a core sample. Accordingly, the latches  520  and  521  are maintained in the position of that illustrated in the upper half of FIG. 2G with the retention members  630  and  632 , such as garter springs (e.g. metal bands) or O-rings that circumscribe the latch members  520  and  521  and bias the latch members  520  and  521  into the recess  604  while the inner barrel  518  is being inserted into the outer barrel  514 . Conversely, the latch members  602  and  608  are positioned as shown in the lower half of FIG. 2F prior to running the inner tube  518  into the bore hole. When the inner barrel  51  is fully inserted into the outer barrel  514 , the inner barrel latch piston  594  is downwardly forced by the running tool  550  thus forcing the latch members  520  and  521  to seat into recess  590  so as to lock the inner barrel  518  relative to the outer barrel  514  as shown in the lower half of FIG.  2 G. At this point, the running tool  550  will automatically disengage from the piston  594  and collet  580  and may be retrieved to the surface. When it is time to retrieve the core sample while leaving the outer barrel assembly  514  downhole, the long assembly pulling tool, generally referred to at  619 , illustrated in FIG. 4C, which includes a long collet extension  620  and long mandrel extension  622 , is employed. In other respects, the pulling tool  619  of FIG. 4C is essentially the same as that shown in FIG.  4 A. The length of the pulling tool  619  in FIG. 4C is such that the pulling tool  619  will cause the ball valve to close and release the upper latch and also to allow tripping of the inner barrel assembly  518 . If in a situation where the inner tube  518  becomes jammed, a medium length pulling assembly  624 , as shown in FIG. 2B, which includes a medium collet extension  626  and a medium mandrel extension  628 , may be employed that is not of sufficient length to close the ball valve  160  but will properly disengage the latching mechanisms so that the inner barrel  518  can still be retrieved while leaving the outer barrel  514  downhole. The inner barrel latch piston  594  is also provided with an emergency pulling tool recess  635  for grasping and retrieving the inner tube  518  without closing the ball valve  160 . In addition, the pulling tool  619  may be provided with a smaller diameter end portion  623 , to engage with a matching smaller recess  638 , so as to provide a tool that will not pull tool  100  with the ball valve in an open position should the tool fail to latch properly. Thus, various profiles of pulling tools may be utilized, each providing a different engagement with the tool  100  for the desired operation. Accordingly, the same pulling tool may be used for all operations with only spacing tubes or extensions added or removed for the particular operation. 
     As shown in the upper half of FIG. 2G, the inner barrel latch  520  locks the inner barrel assembly  518  to the outer barrel assembly  514 . Surface indication of proper operation of the latching mechanisms is provided through an automatic release of the running tool when the inner barrel assembly  518  lands on the shoulder  630  and the latch mechanism  512  correctly locks into position. The landing shoulder  630  locates the inner barrel assembly  518  in its proper relationship to the outer barrel assembly  514 . The weight of the inner barrel assembly  518 , the holding capability of the latch mechanisms  510  and  512  and pump pressure hold it in position during coring operations. 
     The ball valve latch  510  keeps the inner tube assembly  516  secured relative to the outer tube assembly, generally indicated at  129 , to keep the ball valve  160  locked in the open position while running in the hole and during coring. Once coring is complete, the appropriate pulling tool is run to the tool  100  where it locks into recess  638  in the ball valve latch piston  600 . The ball valve latch  510  is released by upward pull on a wireline. Continued upward pull on the wireline lifts the inner tube  126  and closes the ball valve  160 , trapping the core at bottom hole pressure. In addition, completion of the required movement of the inner tube  126  to close the ball valve lifts the inner barrel latch piston  600 , causing latches  602  and  608  to engage with recess  610 , as shown in the upper half of FIG. 2F, as the latches  602  and  608  are inwardly biased by retention members  511  and  513 , releasing the inner barrel assembly  518  from the outer barrel assembly  514 . This allows the inner barrel assembly  518  to be brought to the surface. 
     Preferably, the inner tube latch  512  incorporates a second wireline tool recess  635  which can also be caught with a pulling tool adjusted for significantly shorter engagement. This feature allows the inner tube latch  512  to be caught and released and the inner barrel assembly  518  brought to the surface without closing the ball valve  160 . The wireline tool may also feature a shear pin which activates an emergency release device allowing the wireline to be released in the case of a malfunction so that in a worst case, the drill string can be pulled without having to cut the wireline. 
     To break the core at the conclusion of the coring operation, a pull of approximately 10,000 pounds is applied to the core sample by lifting the drill string to break the core loose from the formation. In the case of sticking in the hole, a maximum pull of 600,000 pounds is allowable. Thus, after the core is severed, a pulling tool is lowered into the hole with a jar down assembly above it. The pulling tool drops into the ball valve latch  510  and is held in the recess  638  (see FIG. 2F) provided therein. When the pulling tool becomes properly engaged with the ball valve latch  510 , a slight pull on the wireline will indicate whether such engagement has been properly achieved. If no resistance is detected, and continued attempts fail to engage the pulling tool with the ball valve latch  510 , the wireline may be pulled up which will cause the pulling tool to latch into the inner barrel latch  520  and retrieve the inner tube assembly  516  without closing the ball valve  160 . This will result in the core being retrieved in a non-pressurized state such that the core sample is subject to ambient pressures. In addition, it may be possible to jar down on the pulling tool allowing it to then pull freely through the inner barrel latch  520  without unlatching, returning it to the surface for refitting. 
     In normal operation with the pulling tool properly engaging the ball valve latch  510  to release the ball valve latch  510 , pulling upwardly on the pulling tool approximately 17 in. to retrieve a core sample of similar length will then close the ball valve  160 . Continued upward pulling of the wireline will then unlatch the upper, inner barrel latch  520  and allow the total inner barrel assembly  518  to trip to the surface with the ball valve  160  closed. In addition, when the assembly trips upward, the magnet  449  in the magnet sub  444  trip the Hall effect switch and activate the TECs. 
     If the ball valve  160  does not completely close, or for some reason the lower barrel is jammed not allowing full travel of the pulling tool, then the inner barrel latch  520  will not be opened. In this case, the pulling tool would be stuck. If this happens, jarring downward will release the pulling tool for retrieval to the surface. An emergency release tool may then be installed on the wireline and lowered back through the drill string. The emergency release tool is configured to latch into the inner barrel latch  520 . Upward pulling of the wireline will release the inner barrel latch  520  and allow the full inner assembly to trip to the surface. 
     Referring now to FIG. 5A, when it is desirable to transfer the core, the safety nut  380  shown in FIG. 2D on the proximal end of the core receiving chamber  360  is removed and a transport adaptor  750  which has external threads  753  along a distal portion  754  thereof is attached to a transport container, generally indicated at  752 . The transport container  752  is attached to the proximal end of the core receiving chamber  360  by threading the transport adaptor  750  into the sleeve  366  (see FIG. 2D) which forms the proximal end of the inner tube  126 . A seal  756  in the adaptor  750  engages a seal surface  375  on the inside of the sleeve  366 . The diameter of the longitudinal bore  758  is sized to match the diameter of the chamber  360  and the distal end  754  of the adaptor  750  is configured so that substantially no gap between the adaptor  750  and the sleeve  366  exists when the two are properly mounted together such that a relatively smooth and flush transition exists to provide a relatively smooth and flush surface for core transfer. 
     As shown in FIGS. 5A and 5B, the transfer container  750  also includes a actuable sealing device or ball valve  160 , generally indicated at  768 , that is similar in configuration to the ball valve  160  shown in FIG.  2 A. The ball valve  768  is comprised of a transport ball valve housing  770  configured to contain a ball  772 . The ball  772  has an internal bore  774  therein defined by a ball liner  776  that is attached to the inside surface  778  of the ball  772 . The diameter defined by the liner  776  is substantially the same as the diameter of the chamber  760  such that a core being transferred to the transport container  752  can relatively easily slide through the ball valve assembly  768 . Similar in configuration to the ball valve assembly  160  illustrated in FIGS. 2A and 2B, the ball  772  is sealed relative to the adaptor  750  with a ball valve seal  780  which is held in place with a ball valve seal retainer  782  secured to the proximal end  784  of the adaptor  750  and a ball valve seat  786 . A transport seal liner  788  is provided on the inside of the seat  786  to provide an internal diameter that substantially matches the internal diameter of the chamber  760 . O-rings  790 ,  791 ,  792 ,  793 , and  794  are provided to seal the various components together to provide a substantially pressure tight chamber  760 . 
     Once the adaptor  750  is properly attached to the sleeve  366 , the pressure inside the transport chamber  760  defined by a transport tube  762 , a ball valve sub  764 , and an end plug  766  is equalized to the pressure inside the core chamber  360  (see FIG.  2 D). The assembly then is checked for leaks to ensure that the transport container  752  is properly mounted to and can sustain the pressure of the core chamber  360 . The release pins  374  of the transfer plug  364  are then unscrewed to allow removal of the plug  364  from the sleeve  366 . The core sample and transfer plug  364  can then be forced into the transport container  752  until the distal end of the core sample clears the ball  772  of the ball valve  768 . The ball  772  is then manually closed by engaging and rotating the pivot pins  800  and  802  which, along with thrust washers  804  and  806  mount the ball  772  to the housing  770 . Dowel pins  808  and  810  are provided to prevent over rotation of the ball  772  relative to the ball valve housing  770 . 
     As further illustrated in FIG. 5A, the end plug  766  is configured similarly to the transfer plug  364  of FIG. 2D in that it includes a longitudinal passageway  812  that is in communication with the chamber  760  such that pressure within the chamber  760  can be controlled and monitored. Accordingly, a burst disk assembly  814  comprised of a burst disk holder  816 , a burst disk  818 , and a burst disk ring  820  are each held in place with a burst disk hold down plug  822  within the chamber  824  provided in the end plug  766 . Additionally, a pressure transducer  826  held in place with a transducer cap  828  and sealed to the plug  766  with o-ring  827  is provided to monitor pressure within the passageway  812  and thus the camber  760 . Bullet valve  830  is also secured to the adaptor  766  and sealed thereto with o-ring  831  and provided such that pressure within the chamber  760  can be increased by securing a pressure source to port  836  and opening the bullet valve  830  or decreased by opening the bullet valve  830  to allow pressurized fluid to vent through port  836 . A plug  832  nay be provided to seal the proximal end  834  of the port  836  which is in fluid communication with passageway  812 . 
     As shown in FIG. 6, the core sample and plug  364  are preferably forced from the core sample chamber  360  by employing a hydraulic piston, generally indicated at  840 , or some other transferring device. The hydraulic piston  840  is connected to the ball valve seal sub  210  (shown in FIG. 2A) The pressure below the ball  162  is equalized and the ball valve  160  opened with external keys. The hydraulic piston  840  is then charged to force the core into the transport container  752 . 
     The hydraulic piston  840  is comprised of an outer housing  842  having an end cap  844  attached to a distal end thereof. A plurality of shaft bearings  846 ,  847 ,  848 , and  849 , in this embodiment four, are positioned within the housing  842 , each having a smaller size than the previously adjacent bearing. A plurality of elongate members or shafts  850 ,  851 ,  852 , and  853 , are secured to a respective bearing  846 - 849  with each shaft  850 - 853  fitting within or about the other shafts, as the case may be. The innermost shaft  853  is secured to a piston cap  856 . The proximal end of the hydraulic piston  840  is provided with an adaptor sub configured to mate with the sealing sub  210  as previously discussed. The outer housing  842  is attached to the sealing sub, as with a threaded connection, and a shaft guide  860 , which acts as a bearing surface, is provided to guide the outermost shaft  850  relative thereto. Each shaft  850 - 852  is provided with a shaft end member  861 - 863 , respectively. Additionally, each component is sealed relative to one another with o-rings  864 - 873 . In operation, the shafts  850 - 853  define an extendable member by telescoping relative to one another such that when a hydraulic or other pressure source is provided and attached to the opening  874  in the end cap  844 , the pressure source enters the chamber  876  defined by the shaft bearings  846 - 849  forcing the shafts  850 - 853  away from the end cap  844  and thus forcing the piston cap  856  into the core chamber  360 . Moreover, the total extendable length of the telescoping shafts  850 - 853  is configured to be able to force the distal end of the core sample through the ball valve  768  of the transport container  752 . Once the core sample has been successfully transferred into the transport container  752  and the ball valve  768  closed, the transport container  752  itself may be placed in a cooling device which will continue to maintain the integrity of the core sample during transport to a laboratory or storage facility. 
     In some instances, it may also be desirable to transport the core sample at ambient pressures. Accordingly, as illustrated in FIG. 7, a relatively simple split tube core receiver, generally indicated at  880 , may be provided to house a core sample during transport. Such a core receiver may be comprised of, as illustrated in the present embodiment, a lock ring adaptor  882  configured to mate with the sleeve  366  shown in FIG.  2 D. The lock ring adaptor  882  is attached to a split tube adaptor  884  with a coupling  886 . The chamber  888  which will house the core sample is defined by a split tube  890 . An end cap  892  defines the proximal end of the split tube core receiver  880 . Even though when using the split tube core receiver  880 , the core sample is not under in situ pressure, the hydraulic piston may still be employed to move the core sample from the core chamber  360  into the split tube core receiver  880 . It is also contemplated that other devices for forcing the core from the chamber  360  may also be employed. 
     It is noted that because the preferred embodiment is generally a cylindrical device and because the various illustrated embodiments herein are shown in cross-section, often only a limited number of the components are visible. For example, while only two latching members  602  and  608  are shown in FIG. 2F, a plurality of such latching members may be circumferentially spaced at that location. A similar arrangement may be provided for the latch members  520  and  521  in FIG. 2G, components of the core catchers  120  in FIG. 4A, as well as others. 
     It will be readily appreciated that the components of the present invention, as generally described and illustrated in the figures herein, could be arranged and designed in a wide variety of different configurations including modifications to and combinations of the preferred embodiments. For example, although the embodiments described herein are particularly adapted for retrieving a core sample at in situ pressure while maintaining a temperature on the core sample, the various components herein described may be utilized on other coring tools where, for example, only in situ pressure is desired to be maintained. In addition, the preferred embodiments are only examples of preferred embodiments. Those skilled in the art after reviewing the present invention will appreciate that there may be other devices known in the art that could be used in place of or in combination with, or that could benefit from, the novel features described in the specific illustrated embodiments. Accordingly, the invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The preferred embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the invention is, therefore, indicated by the appended claims, rather than by the foregoing description of the present embodiments. All changes which come within the meaning of range of equivalency of the claims are to be embraced within their scope.