OIL-WELL SUCKER-ROD PUMP Russian patent published in 1999 - IPC

FIELD: operation of gas, water injection and injection wells. SUBSTANCE: pump includes cylinder and hollow differential plunger with delivery valve whose stage (lesser in section) is provided with suction valve and through radial passage. Differential plunger is provided with partition dividing the cavities of larger and lesser sections and through passage which communicates the cavity of larger section with circular cavity. EFFECT: improved quality of implosive action on well; possibility of pumping out well fluid with no change in equipment only changing point of suspension of casing string. 2 dwg