Patent ID: 6817409
Filing Date: 2004-11-16
Classification: F04B

Abstract:
A positive displacement pump within a wellbore for pumping fluids from a downhole formation to the earth's surface, the pump being reciprocated by a linear actuator, the pump comprising:a plunger moving in response to reciprocal movement of the linear actuator to form an upstroke and a downstroke within the pump, and the pump being configured so as to pump a first volume of fluid upward within the wellbore during the pump's upstroke, and a second volume of fluid upward within the wellbore during the pump's downstroke; a housing having a top end and a bottom end, and defining an elongated bore therein; a sleeve having a top end and a bottom end, and defining an elongated bore therein, the sleeve being nested between the housing and the plunger so as to define a sleeve annulus between the plunger and the sleeve, and a housing annulus between the housing and the sleeve; an upper sleeve head connected to the sleeve and sealing the sleeve annulus; a lower sleeve head connected to the sleeve and sealing the sleeve annulus; and a piston connected to the plunger intermediate the upper sleeve head and the lower sleeve head, the piston residing within the sleeve annulus and reciprocating with the plunger.