US3837412A

US3837412A - Downhole electrical core drilling system

Info

Publication number: US3837412A
Application number: US00312629A
Authority: US
Inventors: W Driver
Original assignee: Individual
Current assignee: SCK Inc
Priority date: 1972-12-06
Filing date: 1972-12-06
Publication date: 1974-09-24
Anticipated expiration: 1991-09-24

Abstract

According to the invention a downhole electrical core drilling system that is lowered into a well hole by an electrical cable to drill a core sample or to drill a well hole. The system consists of a core bit, core barrel and a reduction transmission powered by an electric motor, which is attached to the downhole end of a drill collar, which has its up hole end attached to the electrical cable, which is used to raise and lower the system in a well hole and provide electrical power to the system. The core barrel contains a mechanism, which when activated by a drilled core, cuts the drilled core from the formation from which it was drilled, and holds the drilled core in the core barrel while the system is hoisted to the top of a well hole.

Description

United States Patent [1 1 [111 3,837,412 Driver Sept. 24, 1974 DOWNHOLE ELECTRICAL CORE DRILLING SYSTEM v [76] Inventor: W. 3. Driver, 19 Sheridan Rd.,

Arnold, Md. 21012 [22] Filed: Dec. 6, 1972 [21] Appl. No.: 312,629

[52] US. Cl. 175/104, 175/253 [51] Int. Cl E2lb 3/10, E2lb 9/20, E2lb 25/00 [58] Field of Search 175/104, 245, 251-253 [56] References Cited UNITED STATES PATENTS 478,791 7/1892 Gardner 175/104 X 1,301,395 4/1919 Dale 175/252 2,147,896 2/1939 Harrington 175/253 X 2,743,084 4/1956 Arutunoff 175/104 X 2,769,614 11/1956 Zeni 175/104 X 2,850,265 9/1958 Cruthers. 175/251 2,984,310 5/1961 Meier 175/104 X 3,154,157 10/1964 Anderson 175/253 X FOREIGN PATENTS OR APPLICATIONS 125,255 ll/l90l Germany 175/104 857,032 l1/l952 Germany 175/104 Primary Examiner-David H. Brown [5 7 ABSTRACT According to the invention a downhole electrical core drilling system that is lowered into a well hole by an electrical cable to drill a core sample or to drill a well hole. The system consists of a core bit, core barrel and a reduction transmission powered by an electric motor, which is attached to the downhole end of a drill collar, which has its up hole end attached to the electrical cable, which is used to raise and lower the system in a well hole and provide electrical power to the system. The core barrel contains a mechanism, which when activated by a drilled core, cutsthe drilled core from the formation, from which it was drilled, and holds the drilled core in the core barrel while the system is hoisted to the top of a well hole.

7 Claims, 3 Drawing Figures PAH-1mm 59241914 FIG. 2

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to the drilling of core samples from a well hole and the drilling of oil or gas wells with a downhole electrical core drilling system.

2. Prior Art The drilling of core samples from the earth is presently accomplished by lowering a core bit and barrel attached to a string of drill pipe into a well hole and then drilling the core by rotating the drill pipe. This method works well, but a considerable amount of time and labor is consumed by taking the drill pipe out of the well hole, installing a core bit and barrel, putting the core bit and barrel and drill pipe back in the well hole, and after the core is drilled, taking the core bit and barre] and drill pipe back out of the well hole, and putting the drill pipe with a bit back in the well hole. Another method is core drilling by wire. In this case the core is brought from the well hole by a wire, which is lowered down through the drill pipe string. This system works well and saves time, but the size of the core is quite small and it is not economical to use the system at a deep depth. Also, the drilled cores are pulled or broken from the formations from which they are drilled and this limits the diameter of cores that can be drilled with present equipment.

The drilling of oil or gas wells is accomplished by two methods and they are percussion drilling, which is called cable tool drilling, and rotary drilling. The cable tool drilling equipment is low cost, and requires a small crew, but drilling with cable tools is very slow, and cable tool drilling cannot drill to deep depths The rotary drilling equipment can drill fast and drill to deep depths, but rotary drilling equipment that can drill deep, is very large and expensive, and requires large crews. In drilling with cable tools, when the bit has to be replaced the bit can be brought to the top of the well hole, and a new bit installed and lowered back to the bottom of the well hole in a matter or minutes. To do the same operation from the same depth, with rotary drilling equipment would take several hours and a considerable amount of labor. So cable tool drilling equipment is light mobile and inexpensive but cannot drill deep and fast. Rotary drilling equipment heavy, expensive and not very mobile, but it can drill fast and to deep depths.

SUMMARY OF THE INVENTION Another object of the invention is to provide contained in the core barrel of the system, a mechanism, which when activated by the core being drilled, will cut the drilled core from the formation from which it was drilled, and hold the drilled core in the core barrel while the system is being hoisted to the top of the well hold.

Another object of the invention is to wrap the electrical cable, that raise and lowers the system and supplies electrical power to the system, with a wire coil wound to off-set the back torque from the electrical motor of the system when it is operating.

A primary object of the invention is to provide a downhole drilling system which can drill large deep holes in the earth, with the drilling speed of rotary drilling equipment and have the fast bit replacement capability, crew size, and mobility of cable tool drilling equipment.

DESCRIPTION OF THE DRAWINGS In the accompanying drawings,

FIG. 1 is an overall view of the downhole electrical core drilling system, and a section of the wire cable and related parts.

FIG. 2 is a vertical cross section of the uphole section of the core barrel, which has the mounting plate, latch releasing apparatus, latching apparatus, activating apparatus and the uphole connection of the cut off and catching cable to the activating apparatus.

FIGJ3 is a cross section view of how the cut off and catching cable is mounted in the downhole section of the core barrel during the drilling of a core.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the accompanying drawings, which form a part of this disclosure in FIG. 1 the overall view of the system shows a core bit 1 attached to the downhole end of core barrel 2. Core barrel 2 has one or more holes 11 in its wall near its uphole end, so that drill cutting and fluids can be exhausted from core barrel 2 when a core is being drilled. One or more flat head bolts are used to attach the mounting plate 28 to the inside wall of core barrel 2. The uphole end of core barrel 2 is attached to output shaft 3 of reduction transmission 4. The output shaft 3 rotates core barrel 2 and core bit 1, so that core bit 1 will drill a core. Transmission 4 is attached to the downhole end of electrical motor 5, and the power input shaft of transmission 4 is attached to the power output shaft of electrical motor 5. The uphole end of electrical motor 5 is attached to the downhole end of drill collar 6. Drill collar 6 is used to add weight to the system, when a hole is started or when drilling at shallow depths. The uphole end of drill collar 6 is attached to cable connector 7. The cable connector 7 connects wire cable 9 and flexible wire coil 8 to drill collar 6. Wire cable 9 is used to raise and lower the downhole electrical core drilling system in a well hole. The uphole end of wire cable 9 is attached to conventional electrical reeling equipment at-the top of the well hole. The core of wire cable 9 is a three conductor electrical cable 10, which provides an electrical power circuit from an electrical reel at the top of the well hole, down through wire cable 9, through cable connection 7, through the hollow center of drill collar 6 to an electrical power connection inthe uphole end of electric motor 5. The electrical reeling equipment used to reel wire cable 9 is standard electrical reeling equipment presently available and isnot shown. The wire cable 9 is wrapped full length with wire coil 8. The downhole end of wire coil 8 is attached to cable connection 7. Wire coil 8 is wound around wire cable 9 to off-set back torque, when electric motor 5 is operating. Wire cable 9 and three conductor electrical cable '10 together as described make up an electrical mechanical cable which is known and presently available. All components of the downhole electrical core drilling system are smaller in diameter than core bit 1. The downhole electrical core drilling system is operated by being lowered by wire cable 9, to the bottom of a well hole, and when electrical power is applied through electrical cable to electric motor 5, electric motor 5 through reduction transmission 4 rotates output shaft 3, which rotates core barrel 2 and core bit 1, which drills a core. When a core has been drilled a core cut-off and catching mechanism in core barrel 2 cuts the core from the formation from which it was drilled and holds the core in core barrel 2 while the downhole electrical core drilling system is being hoisted by wire cable 9 to the top of the well hole.

In referring to FIG. 2 and FIG. 3 when a core has been drilled a core cut-off and catching mechanism inside of core barrel 2 cuts the drilled core 19 from the formation from which it was drilled, and holds drilled core 19 inside of core barrel 2 while the downhole electrical core drilling system is being hoisted to the top of the well hole. In FIG. 2, the core cut-off and catching mechanism is activated by the drilled core 19, when the uphole end of drilled core 19 interfaces with solid flange plate 20, and most of the weight of the downhole electrical core drilling system shift from core bit 1 to the uphole end of drilled core 19 through solid flange plate 20 of the latching releasing apparatus. Solid flange plate 20 center corresponds with the center of core barrel 2, and the diameter of solid flange plate 20 is slightly less than the diameter of drilled core 19. The center of the uphole side of solid flange plate 20 is attached to the downhole end of swivel joint 21, which lets core barrel 2 rotate freely when the weight of the downhole electrical core drilling system shifts to the uphole end of drilled core 19. The uphole end of swivel joint 21 is attached to the downhole side of square plug 22, which tits in and is attached to the downhole end of square tube 23, which slips over compression spring 24, and over about half the length of square rod 25. The uphole end of square rod 25 is attached to the center of the downhole side of mounting plate 28. The downhole end of square rod 25 is attached to the uphole end of compression spring 24, and the downhole end of compression spring 24 is attached to the uphole side of square plug 22. Mounting arm 26 has one end attached to square tube 23, and the other end attached to the downhole end of latching releasing rod 27, which extends up through hole 42 in mounting plate 28. The uphole end of latching releasing rod 27 interfaces with the convex side 33 of the latch arm 29 of the latching apparatus. When the weight of the downhole electrical core drilling system shifts to the uphole end of drilled core 19, the compression spring 24 compresses and the square tube 23 slips farther over square rod 25, and latch releasing rod 27 puts releasing pressure on latch arm 29 and latch arm 29 releases.

In FIG. 2 the latching apparatus consist of the latch arm 29 hinged to mounting support 32, which is mounted on the uphole side of mounting plate 28. Hinge bolt 31 hinges latch arm 29 to mounting support 32. Holding spring 34 has one end attached to latch arm 29, and the other end attached to mounting support 32. The purpose of holding spring 34 is to provide pressure on latch arm 29 that tends to keep latch arm 29 in the lock position. Latch arm 29 has a catch 30 which interfaces with the uphole side of round flange plate 35 of the activating apparatus, when latch arm 29 is in the lock position. The side 33 of latch arm 29 between catch 30 and the hinge point is convex, so that side 33 can provide a releasing interface with the releasing rod 27. The uphole end of releasing rod 27 is shaped to provide a releasing interface with side 33. The latching apparatus holds the activating spring 38 of the activating apparatus in compression while the drilled core 19 is being drilled, when the latching apparatus is released, and releases the activating apparatus, the activating apparatus activates the core cut off and catching mechanism, which cuts off and holds the drilled core 19.

In FIG. 2 the activating apparatus consist of square guide rod 37, which has its downhole end attached to the center of the uphole side of mounting plate 28, and extends up through the center of activating spring 38, which has its downhole end interfaced with the uphole side of mounting plate 28. The uphole end of activating spring 38 is interfaced with the downhole side of round flange plate 35. The round flange plate 35 is slightly larger in diameter than activating spring 38, and round flange plate 35 has a square hole in its center that slips over square guide rod 37. The downhole end of square guide tube 36 slips over the uphole end of square guide rod 37. The downhole end of square guide tube 36 is attached to the uphole side of round flange plate 35. One end of the activating arm 39 is attached to square guide tube 36 and the uphole side of round flange plate 35, and the other end of activating arm 39 extends over slot 43 in mounting plate 28 and is attached to the uphole end to cut off and catching cable 15 of the core cut-off and catching mechanism. The activating apparatus functions by putting a force on the uphole end of square guide tube 36, which through round flange plate 35 compresses activating spring 38 until the catch 30 of latch arm 29 interfaces with the uphole side of round flange plate 35, and locks the activating spring 38 in the compressed position. The activating apparatus stays in this position until the catch 30 of latch arm 29 is released by the releasing apparatus, then the activating spring 38 through round flange plate 35 and square guide tube 36, applies an uphole force on activating arm 39 which pulls and maintains an uphole pulling force on the cut-off and catching cable 15 of the core cut-off and catching mechanism.

In FIG. 2 and FIG. 3 the core cut-off and catching mechanism consist of a cut-off and catching cable 15 which has its downhole end clamped to the inside wall of core barrel 2, near the point where the inside wall of core barrel 2 interfaces with the core bit 1, by a end clamp 14. End clamp 14 is held to the inside wall of core barrel 2 by a end clamp bolt 45, which through a hole 44 in end clamp 14, screws into a hole in the inside wall of core barrel 2. Round guide tube 18 has its uphole end interfaced with slot 43 in mounting plate 28, and the downhole end of round guide tube 18 is located about one hundred and eighty degrees around the intercircumference of core barrel 2 from where the downhole end of the cut off and catching cable 15 is clamped to the inside wall of core barrel 2. The downhole end of round guide tube 18 is near the point where the inside wall of core barrel 2 interfaces with core bit 1. The overall diameter of round guide tube 18 is less than the distance from the inside wall of core barrel 2 to the side of drilled core 19. When the compression spring 38 is compressed and the activating apparatus is locked by the latching apparatus, the cut-off and catching cable is held against the inside wall of core barrel 2 by wall clamps 17 from the end clamp 14 to where the cut-off and catching cable 15 enters the downhole end of the round guide tube 18. The cut-off and catching cable 15 extends up through round guide tube 18, through slot 43, and is attached to the end of activating arm 39, which is above slot 43 in mounting plate 28. When the activating apparatus is released the uphole pulling force, which is applied to the uphole end of cut off and catching cable 15, pulls cut off and catching cable 15 from the wall clamps 17 and against the drilled core 19. The cut-off and catching cable 15 has abrasive sections 16 of abrasive material adhered to the part of cut-off and catching cable 15 that interfaces with drilled core 19. The pulling force on cut-off and catching cable 15 from activating arm 39, and the rotation of core barrel 2 provides the power for the abrasive sections 16 to cut the drilled core 19 from the fomation from which it was drilled. After the drilled core 19 has been cut off, the cut-off and catching cable 15 will extend directly from end clamp 14 under the downhole end of drilled core 19, to where cut off and catching cable 15 enters round guide tube 18 and will therefore hold the drilled core 19 inside core barrel 2, while the downhole electrical core drilling system is being hoisted to the top of the well hole.

I claim:

1. Improvements for downhole electrical core drilling systems particularly the type suspended in a well hole by an electrical-mechanical cable and basically consisting of a core bit attached to the downhole end of a core barrel the uphole end of the core barrel attached to and operated by a speed reduction transmission powered by a downhole electric motor and a core break-off or cutoff mechanism contained inside of the core barrel, wherein the improvements comprise: a drill collar, the downhole end of the drill collar is attached to the uphole end of the electric motor, a cable connector attached to the uphole end of the drill collar and to the electrical-mechanical cable, the mechanical part of the electrical-mechanical cable is attached to the cable connector and the electrical part of the electricalmechanical cable extends through the center of the cable connector down through the hollow center of the drill collar and connects to the uphole end of the electric motor, an improved core cut-off and catching mechanism that cuts a drilled core off and holds said core inside of the core barrel, the said core cut-off and catching mechanism is contained inside of the core barrel, an activating apparatus contained inside of the core barrel activates and operates the said core cut-off and catching mechanism, a latching apparatus contained inside of the core barrel keeps the activating apparatus disengaged until a core has been drilled, a latch releasin g apparatus contained inside of the core barrel is activited by interfacing with the uphole end of a drilled core and when activated releases the latching apparatus so the activating apparatus will engage and operate the said core cut off-and catching mechanism, a improved anti-torque device which consist of a flexible wire coil which encloses the electrical-mechanical cable and wound to off set back torque and hold the electrical-mechanical cable stright when the electric motor is operating, the downhole end of the flexible wire coil is connected to the uphole side of the cable connector.

2. In claim 1 one or more holes are drilled in the wall of the core barrel near the uphole end of the core barrel so drill cuttings and fluids can be exhausted from the core barrel when a core is being drilled or when the downhole electrical core drilling system is being lowered into a well hole.

3. In claim 1 a mounting plate is attached to the in side wall of the. core barrel near the uphole end of the core barrel and the latch releasing apparatus is mounted on the downhole side of the mounting plate, the latching apparatus and activating apparatus are mounted on the uphole side of the mounting plate, the core core-cut off and catching mechanism is activated when the desired length of core has been drilled and part of the weight of the downhole electrical core drilling system rest on the uphole end of the drilled core that interfaces with the latch releasing apparatus which supports the said weight on the uphole end of the drilled core and when said weight reaches the desired amount the latch releasing apparatus disengages the latching apparatus, the latching apparatus when disengaged engages the activating apparatus which activates and operates the core cut-off and catching mechanism which cuts off the drilled core and holds said core in the core barrel while the downhole electrical core drilling system is hoisted to the top of the well hole, a core cut-off and catching cable which is apart of the core cut-off and catching mechanism is attached to the activating apparatus and at a point on the inside wall of the core barrel near the core bit. I

4. In claim 3 the latch releasing apparatus consist of a solid flange plate which is slightly less in diameter than the diameter of the drilled core and the center of the solid flange plate corresponds with the center of the core barrel, the flat downhole side of the solid flange plate interfaces with the uphole end of the drilled core, a swivel joint, a square plug and the downhole end of the swivel joint is attached to the center of the uphole flat side of the solid flange plate and the uphole end of the swivel joint is attached to the downhole side of the square plug, the swivel joint lets the solid flange plate interface with the uphole end of the drilled core and remain still while the core barrel is rotating, a square rod attached to the center of the downhole side of the mounting plate, a compression spring attached to the downhole end of the square rod, the downhole end of the compression spring is attached to the center of the uphole side of the square plug, a square tube which encloses the compression spring and slips over half of the square rod, the downhole end of the square tube is closed by and attached to the uphole side of the square plug, a mounting arm, a latchreleasing rod, one end of the mounting arm is attached to the square tube and the other end is attached to the downhole end of the I latch releasing rod, a hole in the mounting plate from the uphole side to the downhole side of the mounting plate is placed so the latch releasing rod can extend through the hole andinterface with the latching apparatus, the uphole end of the latch releasing arm is angled and concaved to provide a releasing interface with the latching apparatus, when the solid flange plate interfaces with a drilled core and the desired weight of the downhole electrical core drilling system shifts from the core bit to the solid flange plate the compression spring compresses and the square tube slips farther over the square rod and the latch releasing arm interfaces with the latching apparatus and disengages the latching apparatus.

5. ln claim 3 the latching apparatus which keeps the activating apparatus disengaged while a core is being drilled consist of a mounting support which is mounted on the uphole side of the mounting plate, a latch arm which is a flat metal bar, the downhole end of the latch arm is hinged to the mounting support, a hinge bolt which hinges the mounting support to the latch arm, one side of the latch arm interfaces with the activating apparatus, a catch is made in the side of the latch arm that interfaces with the activating apparatus and is the part of the latch arm that interfaces with the activating apparatus, the part of the side of the latch arm between the catch and the downhole end of the latch arm is convexed and is the part of the latching apparatus that interfaces with the latch releasing apparatus, when the latch releasing apparatus acts on the latch arm the interface between the catch of the latch arm and the activating apparatus is broken and the activating apparatus engages, a holding spring which has one end attached to the mounting support and the other end attached to the latch arm, the holding spring acts on the latch arm to maintain the catch interface with the activating apparatus.

6. In claim 3 the activating apparatus which activates and operates the core cutoff and catching mechanism consist of a square guide rod and the downhole end of the square guide rod is attached to the center of the uphole side of the mounting plate, a round flange plate, a square hole in the center of the round flange plate large enough to slip over the square guide rod, an activating spring and the uphole end of the activating spring interfaces with the downhole side of the round flange plate, the downhole end of the activating spring interfaces with the uphole side of the mounting plate, the activating spring is mounted so the square guide rod will be in the center of the activating spring, the overall diameter of the activating spring is slightly less than the diameter of the round flange plate, a square guide tube which is large enough to slip over the square guide rod, the downhole end of the square guide tube attaches to the uphole side of the round flange plate around the square hole, an activating arm having one end attached to the square guide tube, part of the downhole side of the activating arm near the end attached to the square guide tube is attached to the uphole side of the round flange plate, the end of the activating arm not attached to the square guide tube is attached to the core cut-off and catching mechanism, the activating apparatus is disengaged by applying downhole pressure on the square guide tube until the activating spring is compressed to the point where the latching apparatus interfaces with the uphole side of the round flange plate and holds the activating spring in a compressed state, the activating apparatus stays lock in this position while a core is being drilled, when the latch releasing apparatus acts on the latching apparatus the interface between the uphole side of the round flange plate and the latching apparatus is broken and the activating apparatus engages, when the activating apparatus engages the activating spring applies and maintains an uphole pressure on the round flange plate, square guide tube and activating arm, the activating arm activates and operates the core cut-off and catching mechanism by applying and maintaining an uphole pulling force on the core cut-off and catching mechanism.

7. In claim 3 the core cut-off and catching mechanism consist of an end clamp that attaches to the inside wall of the core barrel near the point where the downhole end of the core barrel interfaces with the core bit, a counter sunk hole in the end clamp, a threaded hole in the inside wall of the core barrel, a clamp bolt that fits through the counter sunk hole and screws into the threaded hole attaching the end clamp to the inside wall of the core barrel, a round guide tube attached on the inside wall of the core barrel, the overall diameter of the round guide tube is slightly less than the distance from the inside wall of the core barrel to the side of a drilled core, the round guide tube extends from near the point where the downhole end of the core barrel interfaces with the core bit to the mounting plate, the round guide tube is attached to the inside wall of the core barrel so that the downhole end of the round guide tube will be one hundred and eighty degrees around the intercircumference of the core barrel from where the end clamp is mounted, a slot in the side of the mounting plate running from the downhole side of the mounting plate to the uphole side of the mounting plate is located directly over the uphole end of the round guide tube, two or more wall clamps are attached to the inside wall of the core barrel between the downhole end of the round guide tube and the end clamp, the downhole end of the cut-off and catching cable is clamped to the inside wall of the core barrel by the end clamp, the cutoff and catching cable extends into the downhole end of the round guide tube up through the round guide tube, through the slot in the mounting plate, the uphole end of the cut-off and catching cable is attached to the activating apparatus, when the activating apparatus is disengaged the cut-off and catching cable is held against the inside wall of the core barrel between the downhole end of the round guide tube and the end clamp by the wall clamps, when the activating apparatus is engaged and the activating apparatus provides an uphole pulling force on the uphole end of the cut-off and catching cable and is pulled from the wall clamps and against the drilled core, one or more abrasive sections of abrasive material is adhered to the section of the cut-off and catching cable that interfaces with the drilled core, the pulling force on the said cable and the rotation of the core barrel causes the abrasive sections to cut the drilled core until the said cable extends directly from the end clamp to the downhole end of the round guide tube at which point the drilled core will be cut off and the said cable extending directly under the cut off drilled core will hold said core in the core barrel.

Claims

1. Improvements for downhole electrical core drilling systems particularly the type suspended in a well hole by an electricalmechanical cable and basically consisting of a core bit attached to the downhole end of a core barrel the uphole end of the core barrel attached to and operated by a speed reduction transmission powered by a downhole electric motor and a core break-off or cutoff mechanism contained inside of the core barrel, wherein the improvements comprise: a drill collar, the downhole end of the drill collar is attached to the uphole end of the electric motor, a cable connector attached to the uphole end of the drill collar and to the electrical-mechanical cable, the mechanical part of the electrical-mechanical cable is attached to the cable connector and the electrical part of the electrical-mechanical cable extends through the center of the cable connector down through the hollow center of the drill collar and connects to the uphole end of the electric motor, an improved core cut-off and catching mechanism that cuts a drilled core off and holds said core inside of the core barrel, the said core cut-off and catching mechanism is contained inside of the core barrel, an activating apparatus contained inside of the core barrel activates and operates the said core cut-off and catching mechanism, a latching apparatus contained inside of the core barrel keeps the activating apparatus disengaged until a core has been drilled, a latch releasing apparatus contained inside of the core barrel is activited by interfacing with the uphole end of a drilled core and when activated releases the latching apparatus so the activating apparatus will engage and operate the said core cut off-and catching mechanism, a improved anti-torque device which consist of a flexible wire coil which encloses the electrical-mechanical cable and wound to off set back torque and hold the electrical-mechanical cable stright when the electric motor is operating, the downhole end of the flexible wire coil is connected to the uphole side of the cable connector.

3. In claim 1 a mounting plate is attached to the inside wall of the core barrel near the uphole end of the core barrel and the latch releasing apparatus is mounted on the downhole side of the mounting plate, the latching apparatus and activating apparatus are mounted on the uphole side of the mounting plate, the core core-cut off and catching mechanism is activated when the desired length of core has been drilled and part of the weight of the downhole electrical core drilling system rest on the uphole end of the drilled core that interfaces with the latch releasing apparatus which supports the said weight on the uphole end of the drilled core and when said weight reaches the desired amount the latch releasing apparatus disengages the latching apparatus, the latching apparatus when disengaged engages the activating apparatus which activates and operates the core cut-off and catching mechanism which cuts off the drilled core and holds said core in the core Barrel while the downhole electrical core drilling system is hoisted to the top of the well hole, a core cut-off and catching cable which is apart of the core cut-off and catching mechanism is attached to the activating apparatus and at a point on the inside wall of the core barrel near the core bit.

4. In claim 3 the latch releasing apparatus consist of a solid flange plate which is slightly less in diameter than the diameter of the drilled core and the center of the solid flange plate corresponds with the center of the core barrel, the flat downhole side of the solid flange plate interfaces with the uphole end of the drilled core, a swivel joint, a square plug and the downhole end of the swivel joint is attached to the center of the uphole flat side of the solid flange plate and the uphole end of the swivel joint is attached to the downhole side of the square plug, the swivel joint lets the solid flange plate interface with the uphole end of the drilled core and remain still while the core barrel is rotating, a square rod attached to the center of the downhole side of the mounting plate, a compression spring attached to the downhole end of the square rod, the downhole end of the compression spring is attached to the center of the uphole side of the square plug, a square tube which encloses the compression spring and slips over half of the square rod, the downhole end of the square tube is closed by and attached to the uphole side of the square plug, a mounting arm, a latch releasing rod, one end of the mounting arm is attached to the square tube and the other end is attached to the downhole end of the latch releasing rod, a hole in the mounting plate from the uphole side to the downhole side of the mounting plate is placed so the latch releasing rod can extend through the hole and interface with the latching apparatus, the uphole end of the latch releasing arm is angled and concaved to provide a releasing interface with the latching apparatus, when the solid flange plate interfaces with a drilled core and the desired weight of the downhole electrical core drilling system shifts from the core bit to the solid flange plate the compression spring compresses and the square tube slips farther over the square rod and the latch releasing arm interfaces with the latching apparatus and disengages the latching apparatus.

5. In claim 3 the latching apparatus which keeps the activating apparatus disengaged while a core is being drilled consist of a mounting support which is mounted on the uphole side of the mounting plate, a latch arm which is a flat metal bar, the downhole end of the latch arm is hinged to the mounting support, a hinge bolt which hinges the mounting support to the latch arm, one side of the latch arm interfaces with the activating apparatus, a catch is made in the side of the latch arm that interfaces with the activating apparatus and is the part of the latch arm that interfaces with the activating apparatus, the part of the side of the latch arm between the catch and the downhole end of the latch arm is convexed and is the part of the latching apparatus that interfaces with the latch releasing apparatus, when the latch releasing apparatus acts on the latch arm the interface between the catch of the latch arm and the activating apparatus is broken and the activating apparatus engages, a holding spring which has one end attached to the mounting support and the other end attached to the latch arm, the holding spring acts on the latch arm to maintain the catch interface with the activating apparatus.

7. In claim 3 the core cut-off and catching mechanism consist of an end clamp that attaches to the inside wall of the core barrel near the point where the downhole end of the core barrel interfaces with the core bit, a counter sunk hole in the end clamp, a threaded hole in the inside wall of the core barrel, a clamp bolt that fits through the counter sunk hole and screws into the threaded hole attaching the end clamp to the inside wall of the core barrel, a round guide tube attached on the inside wall of the core barrel, the overall diameter of the round guide tube is slightly less than the distance from the inside wall of the core barrel to the side of a drilled core, the round guide tube extends from near the point where the downhole end of the core barrel interfaces with the core bit to the mounting plate, the round guide tube is attached to the inside wall of the core barrel so that the downhole end of the round guide tube will be one hundred and eighty degrees around the intercircumference of the core barrel from where the end clamp is mounted, a slot in the side of the mounting plate running from the downhole side of the mounting plate to the uphole side of the mounting plate is located directly over the uphole end of the round guide tube, two or more wall clamps are attached to the inside wall of the core barrel between the downhole end of the round guide tube and the end clamp, the downhole end of the cut-off and catching cable is clamped to the inside wall of the core barrel by the end clamp, the cut-off and catching cable extends into the downhole end of the round guide tube up through the round guide tube, through the slot in the mounting plate, the uphole end of the cut-off and catching cable is attached to the activating apparatus, when the activating apparatus is disengaged the cut-off and catching cable is held against the inside wall of the core barrel between the downhole end of the round guide tube and the end clamp by the wall clamps, when the activating apparatus is engaged and the activating apparatus provides an uphole pulling force on the uphole end of the cut-off and catching cable and is pulled from the wall clamps and against the drilled core, one or more abrasive sections of abrasive matErial is adhered to the section of the cut-off and catching cable that interfaces with the drilled core, the pulling force on the said cable and the rotation of the core barrel causes the abrasive sections to cut the drilled core until the said cable extends directly from the end clamp to the downhole end of the round guide tube at which point the drilled core will be cut off and the said cable extending directly under the cut off drilled core will hold said core in the core barrel.