Selective control of multi-piston mud pump to create downlink pulse

摘要

A downlink system pumps a drilling fluid to a downhole drilling tool via a standpipe. It comprises a drilling fluid pump 602a that has a number of pumping elements 621, 622, 623. The elements may be pistons. A pump inefficiency controller 628, which is operatively coupled to one or more of the pumping elements, creates a pulse in the drilling fluid flow by selectively reducing the efficiency of the pumping element. The inefficiency controller may be coupled to the intake valve 627 of the pumping element.