초록

A tubular retrieval method involves applying a cyclically varying fluid pressure to the interior of a section of cut bore-lining tubular. The tubular may be casing which it is desired to remove from a bore. A pulling force may also be applied to the tubular.

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1. A tubular retrieval method, comprising: applying a cyclically varying fluid pressure to an interior of a section of a cut tubular lining a bore and having a cut;circulating fluid in the bore above the cut tubular and generating pressure pulses or pressure variations in the circulating fluid; andp

1. A tubular retrieval method, comprising: applying a cyclically varying fluid pressure to an interior of a section of a cut tubular lining a bore and having a cut;circulating fluid in the bore above the cut tubular and generating pressure pulses or pressure variations in the circulating fluid; andproviding fluid communication between the circulating fluid and an isolated section of the cut, whereby the pressure pulses or pressure variations are applied to fluid in the isolated section. 2. The method of claim 1, further comprising establishing a seal across the cut tubular above the cut. 3. The method of claim 1, further comprising establishing a seal across the tubular above the cut and towards an upper end of the cut tubular. 4. The method of claim 1, further comprising establishing a seal across the cut tubular below the cut. 5. The method of claim 1, further comprising applying a pulling force to the cut tubular. 6. The method of claim 1, further comprising engaging the cut tubular with a support member above the cut and applying a pulling force to the cut tubular. 7. The method of claim 6, further comprising passing fluid through the support member. 8. The method of claim 1, further comprising providing a pressure pulse-generating device above the cut tubular. 9. The method of claim 8, further comprising mounting the pressure pulse-generating device in a support member engaging the cut tubular. 10. The method of claim 1, further comprising actuating a pressure pulse-generating device with a circulating fluid. 11. The method of claim 1, further comprising generating pressure pulses in a circulating fluid by operating a valve and providing fluid communication between the circulating fluid above the valve and an isolated section of the cut tubing. 12. The method of claim 1, further comprising generating pressure pulses in a circulating fluid by operating a valve and providing fluid communication between the circulating fluid below the valve and an isolated section of the cut tubular. 13. The method of claim 1, further comprising permitting fluid to pass from an outlet of a pressure pulse-generating device into an annulus between the device and a surrounding tubular. 14. The method of claim 13, wherein the fluid is passed through from the outlet of the device to the annulus via a restricted flow port. 15. The method of claim 1, wherein the varying fluid pressure pushes the cut tubular being retrieved free from a larger diameter tubular surrounding the cut tubular. 16. The method of claim 1, wherein the varying fluid pressure is applied to at least a cross-sectional area of the cut tubular. 17. The method of claim 16, wherein the varying fluid pressure is applied to the cross-sectional area of a larger diameter tubular surrounding the cut tubular. 18. The method of claim 1, wherein the varying fluid pressure dislodges solids in an annulus between the cut tubular a larger diameter tubular surrounding the cut tubular. 19. A tubular retrieval apparatus, comprising: at least one seal positionable to isolate a section of a cut tubular lining a bore and having a cut;a pressure pulse-generating device applying fluid pressure pulses to an isolated section of the cut tubular; anda support member engagable with the cut tubular, wherein the support member includes a gripping device to engage the cut tubular. 20. The apparatus of claim 19, further comprising an upper seal locatable above the cut. 21. The apparatus of claim 20, wherein the upper seal is locatable towards an upper end of the cut tubular. 22. The apparatus of claim 19, further comprising a lower seal locatable below the cut. 23. The apparatus of claim 19, wherein the support member applies a pulling force to the cut tubular. 24. The apparatus of claim 19, wherein the support member is tubular and carries fluid. 25. The apparatus of claim 19, wherein the gripping device is provided on the support member in combination with an upper seal. 26. The apparatus of claim 19, wherein the pressure pulse-generating device is mountable in a support member engaging the cut tubular. 27. The apparatus of claim 19, wherein the pressure pulse-generating device acts on fluid being circulated in the bore above the cut tubular and generates pressure pulses or pressure variations in circulating fluid. 28. The apparatus of claim 27, wherein the apparatus provides communication between the circulating fluid and an isolated section of the cut tubular, whereby the pressure pulses or pressure variations are applied to fluid in the isolated section. 29. The apparatus of claim 19, wherein the pulse-generating device includes a valve operable to vary a fluid flow area, and thereby vary pressure in fluid being passed through the valve. 30. The apparatus of claim 29, wherein the valve is rotatable or oscillatable. 31. The apparatus of claim 29, wherein the pulse-generating device produces a variation in fluid pressure above or below the valve. 32. The apparatus of claim 31, wherein the apparatus provides fluid communication between the fluid above the valve and the isolated section of cut tubular. 33. The apparatus of claim 31, wherein the apparatus provides fluid communication between the fluid below the valve and the isolated section of tubular. 34. A tubular retrieval apparatus, comprising: at least one seal positionable to isolate a section of a cut tubular lining a bore and having a cut;a pressure pulse-generating device applying fluid pressure pulses to an isolated section of the cut tubular; wherein the pressure pulse-generating device is actuatable by fluid being circulated in the bore. 35. The apparatus of claim 34, wherein the pulse-generating device comprises a positive displacement motor. 36. A tubular retrieval apparatus, comprising: at least one seal positionable to isolate a section of a cut tubular lining a bore and having a cut;a pressure pulse-generating device applying fluid pressure pulses to an isolated section of the cut tubular; andwherein the apparatus permits fluid to pass through a port from an outlet of the pressure pulse-generating device into an annulus between the device and the surrounding cut tubular. 37. The apparatus of claim 36, comprising a nozzled flow port through which the fluid passes from the device outlet to the annulus. 38. The apparatus of claim 36, wherein the port opens and closes. 39. The apparatus of claim 36, wherein the pulse-generating device is de-activatable by closing a flow port. 40. A tubular retrieval method, comprising: applying a cyclically varying fluid pressure to an interior of a section of a cut tubular lining a bore and having a cut; wherein the cyclically varying fluid pressure establishes fluid circulation in an annulus between the cut tubular and a larger diameter tubular surrounding the cut tubular.