Method for cryogenically freeing drilling pipe |
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| 申请号 | US3756317D | 申请日 | 1972-02-09 | 公开(公告)号 | US3756317A | 公开(公告)日 | 1973-09-04 |
| 申请人 | HALL G; | 发明人 | HALL G; | ||||
| 摘要 | A method of freeing drilling pipe in a well bore which has become stuck or seized through a differential pressure condition within the bore wherein a torque is maintained on the drill pipe, the zone of differential pressure determined within rough limits, a cryogenic tool or carrier is positioned so as to correspond generally to the zone, the tool then being actuated and forming a thin, temporary ice or frozen sheath between the bore hole and drill pipe thus losing a substantial portion of the bore hole permeability and consequent differential pressure, the torque and/or heat applied to the drill pipe breaking the ''''sheath'''' and continuing rotation of the pipe. | ||||||
| 权利要求 | 1. A method for freeing drill pipe seized in a bore hole at a low pressure formation zone by the differential pressure between that zone and the media within the bore hole, comprising: A. determining the location and extent of the low pressure zone; B. withdrawing sufficient heat from the surface of the low pressure zone in contact with the drill pipe to momentarily reduce the permeability of said surface and thus the differential pressure throughout a substantial portion of its length; and C. applying a force to the drill pipe to break it free of the surface during the period of reduced differential pressure. 2. The method defined by claim 1 wherein said step for withdrawing heat comprises: A. lowering a selectively actuatable heat transfer means slideably within the drill pipe; B. positioning the heat transfer means so that at least a portion thereof substantially coincides with the determined location and extent of the low pressure zone; C. selectively cryogenically cooling temporarily that portion of the heat transfer means which coincides with the low pressure zone to thereby alter the viscosity of any fluid in the contact area of the pipe-low pressure zone a sufficient amount to materially reduce the differential pressure thereof thereby permitting the applied drill pipe force to overcome the remaining differential pressure. 3. The method defined by claim 2 wherein said selective temporary cooling is continued until the fluid in and adjacent the contact area of the pipe-low pressure zone freezes. 4. The method defined by claim 1 wherein said step for withdrawing heat comprises: A. positioning a heat transfer means slideably within the drill pipe; B. lowering the heat transfer means through the drill pipe at its ambient temperature; C. positioning a first portion of the heat transfer means so that it substantially coincides with the drill pipe-low pressure zone interface; D. selectively actuating the heat transfer means so that the first portion thereof causes a rapid cooling at and adjacent the drill pipe-low pressure zone interface; E. terminating the cooling when the drill pipe breaks free of its adhesion to the bore hole wall; and F. retrieving the heat transfer means. 5. The method defined by claim 4 wherein said rapid cooling is continued until the interface of the pipe-low pressure zone forms an ice sheath. 6. A method for freeing casing seized in a bore hole by the differential pressure resultant from the casing contacting a permeably low pressure formation within the bore hole comprising: A. determining the location and extent of the low pressure formation; B. assembling a freeze tool of sufficient length to substantially coincide with the extent of the permeable low pressure formation; C. attaching thereto a liquified gas carrier and insulating means of sufficient volume to cause the freeze tool on application to change the character of the surface of the low pressure formation where contacted by the casing to a relatively impermeable condition; D. lowering the freeze tool and carrier as a unit within the casing; E. locating and positioning the assembled freeze tool within that portion of the casing substantially corresponding to the low pressure formation; F. transferring liquified gas from the carrier and insulating means to the freeze tool; G. rapidly expanding the transferred liquified gas within the freeze tool to cause the tool to withdraw heat from the drill pipe, the intermediate area and material, and low pressure formation immediately adjacent at least the casing surface seized; H. applying a torque to the casing during said heat withdrawal step; I. continuing said heat withdrawal until a frozen or substantially impervious sheath is formed momentarily on the casing contacted low pressure formation bore hole wall substantially reducing the differential pressure and releasing the torqued casing; and J. retrieving the carrier and freeze tool units. |
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