US Patent 7857067 Downhole application for a backpressure valve

A backpressure valve. The backpressure valve may be configured to maintain a substantially controlled pressure in bottom hole assembly while simultaneously being compatible with a pressure pulse tool downhole thereof. The backpressure valve includes pressure generating capacity below its internal valve assembly so as to avoid the tendency of the assembly to throttle open and closed. Furthermore, the pressure generation is achieved in a manner avoiding cavitation. As a result, once the backpressure valve is opened, the pressure pulse tool is able to reliably communicate with surface equipment at the oilfield.