Hydraulic Feed Back Pump For Heavy Crude Oil

The pump operates by means of the change of an annular space formed by a major plunger and a minor plunger, and there is no standing valve in the pump. The plunger moves with the help of the feedback force during the pump operation. The pump can work smoothly in a heavy crude oil well with the viscosity smaller than 4000 centipoises. It is not necessary to install the oil drainers in down-hole and the well testing and vapor injection operation can be done without lifting the tubing strings.