Debris removal from wellbores

摘要

An apparatus and method for removing sand and other debris from a wellbore. The apparatus is particularly suited for wireline operation, and requires minimal surface equipment. A housing is lowered into the wellbore until the housing is proximate to the sand, and a valve is opened to permit entry of the sand into a housing chamber. The housing can be raised to the wellbore surface so that the sand can be removed from the housing chamber. In one embodiment of the invention, the housing has two chambers each having a floating piston. A liquid is initially retained within the first chamber and is pressurized as the housing is lowered into the wellbore. Activation of a valve and differential pressures acting across the first piston move the liquid into the second chamber and draw the sand into the first chamber. The second chamber captures the liquid and facilitates return of the pistons to the initial position after the sand is emptied from the first chamber.