| 摘要 |
The present invention provides methods for expanding a tubular with the aid of a compressive force. A tubular (140), such as a string of casing, is run into a wellbore (100) on a working string (200), e.g., drill pipe. A carrying mechanism (150) such as a collet is used to releasably attach the tubular to the working string during run-in. The tubular is then expanded into frictional engagement with another tubular (110) therearound within the wellbore. During the expansion process, a compressive force is applied to the portion of the tubular (140U) being expanded. In one aspect of the invention, a hydraulic ram (400) is positioned above the string of casing (140) and is activated by the injection of fluid under pressure in order to apply the compressive force to the expandable tubular. In another aspect of the invention, the portion of casing or other expandable tubular to be expanded is pre-stressed (140B), such as to impart a barrel shape, in order to bias the tubular to more easily buckle outwardly during expansion.
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