Claims
- 1. An apparatus for taking a core sample of rock from a subterranean formation, comprising:
- a pressure core barrel including:
- an outer barrel having a core bit secured to the lower end thereof adapted to cut said core sample for receipt by said core barrel;
- an inner tube assembly adapted to receive said core sample and maintain said core sample under pressure; and
- a non-invasive gel disposed in said inner tube assembly for encapsulating said core sample as it is received by said inner tube.
- 2. The apparatus of claim 1, wherein said inner tube assembly includes a valve at the lower end thereof for sealing said inner tube assembly and maintaining said pressure.
- 3. The apparatus of claim 1, wherein said core bit comprises an anti-whirl core bit.
- 4. The apparatus of claim 1, further including a cooperative cutter arrangement on said core bit and an adjacent pilot shoe at the lower end of said inner tube assembly configured and mutually arranged to protect said core sample from drilling mud contamination as said core sample is being cut and received in said inner tube assembly.
- 5. The apparatus of claim 4, wherein said core bit comprises an anti-whirl core bit.
- 6. A method of taking a core sample of rock from a subterranean formation at the bottom of a borehole filled with drilling fluid, comprising:
- providing a pressure core barrel including an outer barrel having a core bit secured to the lower end thereof, and an inner tube assembly structured to receive a core sample cut by said core bit and to maintain said core sample under pressure;
- disposing a quantity of non-invasive gel in said inner tube assembly;
- running said core barrel to the bottom of said borehole at the end of a drill string;
- cutting said core sample by rotating said outer barrel with said drill string and engaging said formation with said core bit;
- receiving said core sample in said inner tube assembly as it is cut and encapsulating said core sample as it is received with said non-invasive gel;
- trapping said core sample under pressure in said inner tube assembly; and
- retrieving said core barrel with said pressurized, encapsulated core sample contained in said inner tube assembly.
- 7. The method of claim 6, further including spotting a pill of coring fluid having a high viscosity, low spurt loss and compatibility with said drilling fluid at the bottom of said borehole before placing said core barrel at the bottom of said borehole.
- 8. The method of claim 7, further including tagging into said pill with said pressure core barrel immediately before cutting said core sample.
- 9. The method of claim 8, further including circulating an additional quantity of coring fluid having a high viscosity, low spurt loss and compatibility with said drilling fluid down said drill string through said drill string and cutting said core sample of said rock while circulating said coring fluid out of said core bit against said formation.
- 10. The method of claim 9, further including bleeding off pressure in said inner tube assembly after said retrieval, and trapping a sample of gas contained in said inner tube assembly.
- 11. The method of claim 10, further including draining coring fluid trapped in said core barrel.
- 12. The method of claim 11, wherein said bleeding off pressure and removing coring fluid are performed substantially simultaneously.
- 13. The method of claim 7, further including the step of circulating an additional quantity of coring fluid having a high viscosity, low spurt loss and compatibility with said drilling fluid down said drill string through said drill string and cutting said core sample of said rock while circulating said coring fluid out of said core bit against said formation.
- 14. The method of claim 6, further including bleeding off pressure in said inner tube assembly after said retrieval, and trapping a sample of gas contained in said inner tube assembly.
- 15. The method of claim 14, further including draining coring fluid trapped in said core barrel.
- 16. The method of claim 15, wherein said bleeding off pressure and removing coring fluid are performed substantially simultaneously.
- 17. The method of claim 6, further including circulating a quantity of coring fluid having a high viscosity, low spurt loss and compatibility with said drilling fluid down said drill string through said drill string and cutting said core sample of said rock while circulating said coring fluid out of said core bit against said formation.
Parent Case Info
This invention is a continuation-in-part of U.S. patent application Ser. No. 08/051,093, filed Apr. 21, 1993, now U.S. Pat. No. 5,360,074 which is hereby incorporated herein by reference and a continuation-in-part of U.S. patent application Ser. No. 08/214,392 filed Mar. 16, 1994, also hereby incorporated herein by reference.
US Referenced Citations (26)
Foreign Referenced Citations (2)
Number |
Date |
Country |
0403437 |
Jun 1990 |
EPX |
2152109 |
Jul 1985 |
GBX |
Non-Patent Literature Citations (2)
Entry |
Huey, David, P., "New Downhole Tools Improve Core Recovery", Oil & Gas Journal, pp. 42-47, Jan. 23, 1995. |
Two-page description of the structure and operation of a prior art Eastman Christensen Pressure Core Barrel (Undated). |
Continuation in Parts (1)
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Number |
Date |
Country |
Parent |
51093 |
Apr 1993 |
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