Downlink pump connected to standpipe for generating mud pulses

摘要

A method of generating a downlink signal comprises pumping a drilling fluid from a mud pit 704 to a downhole drilling tool. A downlink pump 711 has an intake in fluid communication with a standpipe 708 and a discharge that is also in fluid communication with the standpipe. The mud flow rate may be selectively alternately increased and decreased using the downlink pump to create mud pulses to be received by the drilling tool. Alternatively, the downlink pump is connected in parallel with at least one primary drilling fluid pump, and is selectively turned on and off by electronic circuitry. The downlink pump may be a piston pump or a diaphragm pump (811, fig 8).