US Patent 7905289 Double-acting jar compounder

A double-acting compounder is disclosed having a first end and a second end, and comprising an outer housing, an upper mandrel, and a lower mandrel. The outer housing defines the first end. The upper mandrel is at least partially disposed telescopically within the outer housing to define an uphole fluid chamber between the upper mandrel and the outer housing, the upper mandrel defining the second end. The lower mandrel is at least partially disposed telescopically within the outer housing to define a downhole fluid chamber between the lower mandrel and the outer housing. The uphole fluid chamber and the downhole fluid chamber each contain fluid, have a variable stroke-dependent volume, and are sealed at an uphole end and a downhole end. The upper mandrel has a first shoulder engagable with and facing a second shoulder of the lower mandrel to move the lower mandrel during at least a portion of a stroke.