DOWNHOLE SUCKER-ROD PUMPING UNIT Russian patent published in 1997 - IPC

FIELD: oil producing industry, in particular, oil production; applicable in recovery of any type of formation fluid, for instance, of water. SUBSTANCE: pumping unit consists of two concentric tubing strings, sucker-rod string arranged inside tubing string and downhole pumping devices. Each downhole pumping device is made in form of body with annular channel, cylinder with holes, piston and hollow rod. Hollow rod is rigidly connected with sucker-rod string. Downhole pumping device has intake and pressure valves. Internal tubing string is divided and isolated in height into autonomous lifting intervals. For this purpose, it has upper and lower partitions. Piston is located between the partitions, rigidly connected with hollow rod and forms together with upper and lower partitions, correspondingly, upper and lower chambers. The latter is connected, via cylinder hole, with annular space between tubing. Upper chamber is communicated with rod hollow and forms transfer device. Present in annular space are cone partitions and fluid. Density of this fluid ensures, by pressure of its column, movement of piston upward. EFFECT: higher efficiency of unit operation due to utilization of pressure of hydrostatic column of fluid. 1 dwg