Systems and methods for surging fluid downhole in an earth borehole, as well as tools especially adapted for use in such systems and methods, are disclosed. In a system for surging fluids, upper and lower valves both operated through the use of annulus pressure define the upper and lower extremities of a surge chamber. In a multiple surge system, first and second surge chambers are provided and a further valve is operative to surge fluids from the first surge chamber into the second surge chamber. A valve is disclosed having a longitudinal passageway initially closed by a breakable closure member. The valve is opened by breaking the closure member, and removing the broken closure member from the longitudinal passageway. The valve is operated by pressure differential between annulus pressure and atmospheric pressure which serves to accelerate a massive cutter member into the closure member for opening it. Also, a fluid pressure actuated apparatus especially useful in operating the upper valve is disclosed. A mechanism enables the operation of the valve in response to the elevation of fluid pressure within the valve, so that the operation of the upper valve with the use of annulus pressure is independent of the operation of the lower valve.