| 摘要 |
One embodiment of the present invention discloses a well pressure activated pack off head to be used in conjunction with a wellhead situated on a hydrocarbon producing wellbore. The well pressure activated pack off head comprises a hollow body formed for coaxial connection to the wellhead, the hollow body must also provide for unobstructed passage of a data transmitting wireline therethrough. Disposed within the hollow body is a pack off rubber with a passage formed along its longitudinal axis for passage of a data transmitting wireline therethrough The pack off rubber is coaxially situated within the hollow body. The pack off rubber can be formed from numerous materials, but the material must be pliable enough under the conditions of use to provide a pressure seal between it and the wireline passing through its axis. Also located in the hollow body, above and proximate to the pack off rubber, is a pack off bushing. The pack off bushing is coaxial to the hollow body and has an axial passage formed along its axis to allow for passage of a data transmitting wireline through its axis. The pack off bushing should have a higher hardness than the pack off rubber, typical materials include brass or hard face steel. The well pressure activated pack off head further includes a piston coaxially situated within the hollow body and also has an axial passage formed concentric along its axis that allows for passage of a data transmitting wireline through it. The bottom of the piston is its wellbore pressure side and its top is its ambient pressure side. The wellbore pressure side of the piston is in pressure communication with the wellbore. The ambient pressure side of the piston is in pressure communication with the ambient space surrounding the pressure pack off head. The piston is situated below the pack off rubber, which puts the pack off rubber between the piston and the pack off bushing. When the pressure of the wellbore, and thus the wellbore pressure side, exceeds the ambient pressure, the pressure differential experienced by the piston urges it toward the pack off bushing and pack off rubber. Continued upward movement of the piston causes the piston to contact the pack off rubber and push the pack off rubber against the pack off bushing. This pushing action compresses the pack off rubber between the piston and the pack off bushing such that compression of the pack off rubber compresses the pack off rubber axial passage around the data transmitting wireline. Compression of the pack off rubber axial passage around the data transmitting wireline eventually provide a pressure seal between the pack off rubber axial passage and the data transmitting wireline passing therethrough.
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