Soft formation core barrel |
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| 申请号 | US3621924D | 申请日 | 1970-03-24 | 公开(公告)号 | US3621924A | 公开(公告)日 | 1971-11-23 |
| 申请人 | LEBOURG MAURICE P; | 发明人 | LEBOURG MAURICE P; | ||||
| 摘要 | A core barrel device for producing and retrieving subterranean cores, particularly from soft or unconsolidated formations, utilizes a fluid-pressure collapsible sleeve above the corer to receive and hold the core material and permit its retrieval in its original subterranean condition. Pressure responsive valves maintain a fluid pressure behind the collapsible sleeve to retain it in the collapsed position until the core is received in the sleeve and also permit fluid behind the sleeve to exhaust as the core enters the sleeve while the sleeve continues to offer lateral pressure support for the core and also remains collapsed above the core. When the coring device is withdrawn, a small amount of core material falls from the lower portion of the core barrel and the lower portion of the sleeve collapses to retain the remainder of the core within the core barrel. | ||||||
| 权利要求 | 2. The apparatus of claim 1 including: a tubular core barrel structure; means for mounting said cutting means at the lower end of said core barrel; and means for mounting said sleeve means within said core barrel structure above said cutting means to provide a volume between the outer surface of said sleeve means and said core barrel wherein a fluid may be maintained under pressure. 3. The apparatus of claim 2 including means for introducing a fluid to said volume at a pressure greater than the fluid pressure within said sleeve means. 4. The apparatus of claim 2 including: means for interconnecting said core barrel structure in a rotary well drilling string. 5. The apparatus of claim 2 including fluid channel means in said core barrel structure for directing a drilling fluid to the region of said cutting means. 6. The apparatus of claim 5 including first valve means disposed between said channel means and said volume to admit fluid to said volume at a first fluid pressure level; and second valve means disposed between said channel means and said volume to exhaust fluid from said volume at a second fluid pressure level wherein said second fluid pressure level is greater than said first fluid pressure level. 7. The apparatus of claim 5 including fluid jet means in said cutting means communicating with said fluid channel means, said jet means being disposed to direct fluid toward the formation around the core to assist in cutting and forming the core. 8. The apparatus of claim 1 wherein said sleeve means includes at least two longitudinally disposed reinforcing means arranged at spaced positions at the periphery of said sleeve means to permit said sleeve means to collapse from at least said positions on its periphery. 9. The apparatus of claim 1 wherein said sleeve has a preferentially collapsible portion near the bottom thereof. 10. An apparatus for producing and retrieving subterranean formation cores which comprises: a tubular core barrel means; cutting means disposed at the lower portion of said core barrel means for cutting said core; collapsible sleeve means disposed within said core barrel means above said cutting means and defining a volume between the outer surface of said sleeve means and said core barrel, wherein fluid may be maintained under pressure; first valve means to maintain a fluid within said volume at a preselected pressure greater than the fluid pressure within said sleeve to maintain said sleeve in collapsed position until said core is received therein; and second valve means to exhaust fluid from said volume in response to decrease of said volume resulting from said core entering said sleeve. 11. The apparatus of claim 10 wherein said tubular core barrel means comprises an outer barrel and an inner barrel defining a fluid channel therebetween, and wherein said first and second valve means communicate between said channel and said volume. 12. The apparatus of claim 11 including means for exhausting fluid from said volume to said fluid channel means when said core enters said sleeve. 13. The apparatus of claim 12 wherein said means for admitting fluid and said means for exhausting fluid comprise first and second one-way check valves which open at predetermined pressure gradients, and wherein the pressure gradient required to open said second valve is greater than that required to open said first valve. 14. The apparatus of claim 11 wherein said outer barrel includes means for interconnection in a rotary well drilling string and wherein said outer barrel is rotatable independent of said inner barrel. 15. The apparatus of claim 11 including fluid jet means in said cutting means communicating with said fluid channel means, said fluid jet means being disposed to direct fluid against the formation around the core to assist in the cutting and formation of said core. 16. The apparatus of claim 11 wherein said means for admitting fluid is located at first position in said fluid channel means and including pressure equalizing means located at a second position in said fluid channel means downstream from said first position, said pressure equalizing means communicating between said fluid channel means and the interior of said sleeve to equalize fluid channel means and the interior of said sleeves to equalize fluid pressure therebetween. 17. The apparatus of claim 10 including at least two longitudinal reinforcing means disposed around the periphery of said sleeve at regularly spaced positions and adapted to maintain the outer surface of said sleeve proximate to the inner surface of said inner barrel at said positions and permitting said sleeve means to collapse from said positions on its periphery in response to fluid pressure within said volume. 18. Apparatus for producing and retrieving a formation core by rotary drilling which comprises: a core barrel structure comprising an outer barrel and an inner barrel defining a fluid channel therebetween, said outer barrel being freely rotatable relative to said inner barrel; a cutting means mounted on the lower portion of said outer barrel and rotatable with said outer barrel for cutting the formation to produce a core, said cutting means providing the termination of said fluid channel means; a tubular, collapsible sleeve disposed within said inner barrel above said cutting means for internally receiving the core produced, said sleeve means defining a volume between the outer surface thereof and said inner barrel; first check valve means fOr admitting fluid from a first position in said channel to said volume at a first pressure greater than the fluid pressure within said sleeve to collapse said sleeve prior to receipt of the core therein; second check valve means for exhausting fluid from said volume to said channel at a second pressure greater than said first pressure, said second pressure being insufficient to deform said core; and pressure equalization means disposed to equalize the fluid pressure between a second position in said channel downstream of said first position and the volume within said sleeve. 19. Apparatus for producing and retrieving formation cores from beneath the surface of a body of water which comprises: a coring tube; cutting means on the lower end of said tube for producing said core; a collapsible sleeve disposed within said tube, said sleeve defining a sealable volume capable of retaining a fluid under pressure; differential pressure means to supply a fluid to said volume at a fluid pressure greater than hydrostatic pressure; exhaust check valve means disposed to exhaust fluid within said volume to said body of water, said check valve being openable in response to a preselected gradient between said pressure within said volume and hydrostatic pressure. 20. A method for producing and retrieving a formation core which comprises: cutting the formation to produce a core; accepting said core axially into a collapsible sleeve; applying a fluid pressure to the outer surface of said sleeve to collapse said sleeve above said core; and controlling said fluid pressure behind said sleeve to permit yieldable expansion of said sleeve from the collapsed position to an expanded position to accept said core. 21. The method of claim 20 wherein said core is cut by rotary drilling. 22. The method of claim 20 including the step of circulating a fluid to the formation in the cutting region to assist in cutting said core. 23. The method of claim 20 wherein said core is retrieved from a location under a hydrostatic head of pressure including the steps of raising said core while in said sleeve, and reducing said fluid pressure behind said sleeve in response to the reduction of hydrostatic pressure as said core is raised. 24. A method for producing and retrieving a formation core from a borehole which comprises: cutting the formation to produce a core; establishing a fluid flow path to circulate a fluid to the bottom of said borehole in the cutting region, said fluid flow path offering resistance to said fluid flow to create a dynamic pressure drop across said path from a first position above the bottom of said borehole to a second lower position proximate the bottom of said borehole; accepting said core axially into a collapsible sleeve; applying a fluid pressure corresponding to said fluid pressure at said first position to the outer surface of said sleeve to collapse said sleeve above said core; equalizing dynamic fluid pressure between fluid at said second position and fluid within said sleeve; and controlling said pressure behind said sleeve to permit yieldable expansion of said sleeve to accept said core. 25. The method of claim 24 wherein said core is cut by rotary drilling. 26. The method of claim 24 including the steps of lifting said core from the bottom of said borehole; continuing circulation in said fluid path while said core is lifted from the bottom of said borehole; permitting the lower portion of said core to fall to the bottom of said borehole; and collapsing said sleeve below the remainder of said core to capture said core. 27. The method of claim 24 wherein said borehole is filled with liquid including the additional steps of raising said core in said borehole; and reducing the pressure behind said sleeve in response to the reduction of hydrostatic pressure as said core is raised in said borehole. |
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