Abstract: A method of improving the flow of fluids into or along a deviated wellbore that has a partial or complete obstruction caused by fill particles, comprising removing the fill particles from the obstruction and depositing the fill particles within the wellbore, uphole and/or downhole of the partial or complete obstruction. The method described herein removes obstructions and/or stimulates a well in which productivity has been impaired by the presence of fill in the wellbore. This is accomplished without removing the fill from the wellbore, and therefore avoids the consequent disposal or storage considerations.

Abstract: A pump for pumping fluid down a well bore in a rock formation comprises: intake and discharge passages; a pumping chamber with a plunger therein; intake and discharge valve assemblies in the intake passage and the discharge passages. At least one valve assembly has a valve body movable into sealing contact with the valve seat by fluid pressure in the pumping chamber. The valve seat may have a cylindrical outer surface for mating reception in said intake passage, and a shoulder with a radially-projecting surface biased against a wall for sealing. A cushioning member may be interposed between the valve body and the valve seat. A seal may be interposed between said valve body and said valve seat, and configured so that between 35% and 60% of a sealing surface of said valve seat contacts the valve body.