Apparatus and method for modifying loading in a pump actuation string in a well having a subsurface pump

摘要

A housing unit installed within a tubing string of a oil well, water well, or gas dewatering well contains at least one reciprocating plunger which utilizes the hydraulic head of the fluid in the tubing to modify the loading in a subsurface pump actuation string, such as a string of sucker rods. The device can be used to either reduce observed polished rod loads at the surface to reduce the required counterbalance, or the device can be used to provide additional loading in the pump actuation string above the pump to reduce buckling. The device is used in a method for modifying the loading in a subsurface pump actuation string.

主权项

1. In a fluid producing well in which a subsurface pump is actuated by an actuation string extending to the subsurface pump, said pump lifting fluid from the subsurface to a higher elevation through a tubing string having an interior and an exterior, said fluid producing a hydrostatic pressure inside the tubing string, an apparatus for changing loading in the actuation string, the apparatus comprising:
a. an upper plunger slideably disposed inside an upper barrel, the upper plunger having a first axial opening extending through an upper interior; b. a lower plunger slideably disposed inside a lower barrel, the lower barrel having an interior and an exterior, the lower plunger having a second axial opening extending therethrough, wherein the upper barrel and the lower barrel are connected together by an intermediate connector to comprise a tube member, the tube member made up as a component of the tubing string; c. said lower barrel having a different cross-sectional area than said upper barrel; d. a fluid communication means in the intermediate connector which allows fluid communication from the interior of the lower barrel to the exterior of the tubing string; and e. the actuation string extending through and below the upper plunger and the lower plunger to operate the subsurface pump which is set below the lower plunger.