| 摘要 |
<p>of the Invention Methods and means wherein a downhole reciprocating oil well pump powered by a source of pressurized fluid located at the wellhead receives fluid power via one tubing string and pumps liquid from the well through another tubing string, the downhole pump having internal means to vent gas and vapor from the pump chamber and to cause a pump stroke only when the pump chamber becomes filled with liquid. Means are provided to expel sediment from the pump chamber prior to a pump stroke and a method to independently vary the speed of the pump and return strokes and disclosed so as to conserve energy and reduce maintenance.</p> |
