Importance

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Abstract

A leakproof seal arrangement is disclosed for use in the drivehead of a downhole rotary pump, which pump is operated by a drive string suspended from the drivehead for rotation in a production tubing about a longitudinal axis, the drivehead having a bore in fluid communication and coaxial with the production tubing and sized to permit the passage of a polished rod attached to a top end of the drive string. The seal arrangement includes a centralizer sleeve for receiving a portion of the polished rod; a bearing for rotatably supporting the centralizer sleeve in the drivehead coaxial with the bore, whereby an annular gap is created between the centralizer sleeve and an opposite, cylindrical wall of the drivehead which gap is in fluid communication with the production tubing. The seal arrangement further includes a centering packing for sealingly and concentrically connecting the centralizer sleeve with the polished rod for simultaneous rotation about the longitudinal axis. The centering packing is sufficiently elastic to accommodate wobble of the polished rod in the centralizer sleeve while preventing leakage of a pumped liquid present in the production tubing and the centralizer sleeve during operation of the pump. The seal arrangement also includes an annular drivehead seal for sealing the annular gap which is also filled with the pumped liquid during operation of the pump, to substantially prevent leakage of the pumped liquid from the drivehead. With this seal arrangement, polished rod wobble compensation and sliding sealing of the drivehead are carried out at separate locations in the drivehead which results in a more reliable seal and reduced stress on the seal materials used and provides the seal with an extended service period.

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First Claim