Drillstring combination pressure reducing and signaling valve

Abstract

A drillstring combination pressure reducing and signaling valve assembly uses multiple ball valves mounted in parallel, each having a different bore, to meter the flow through a drillstring. The individual ball valves are maintained in either a fully open or a fully closed position, but can be selectively moved between these two positions. The bores of the individual ball valves are sized so that at a given pressure, a first ball valve has a predetermined flow rate, a second ball valve has twice the flow rate of the first ball valve, a third ball valve has twice the flow rate of the second ball valve, and the remaining ball valves each have twice the flow rate of their predecessor in the valve sequence. This arrangement permits the flow rate and flow pressure drop through the assembly of valves to be digitally controlled by varying the combination of open and closed valves. In addition, another ball valve serving as a signaling valve is rapidly shifted either between a closed position, an open position, and back to a closed position. The signaling valve serves as a bidirectional signaling valve by relaying sensed pressure pulse signals emanating from either above or below the signaling valve past the valve assembly. Alternatively, the additional ball valve can be rapidly shifted between an initial open position to a closed position and then to a final open position. Pressure sensing is provided both above and below the valve assembly, and operative and control means are provided for the valve assembly.