Measuring and transmitting apparatus used in drill string - is self-contained and forms output signals modulated into mud flow

摘要

Appts. for use in a drill string forms a signal of downhole drilling information. It has a tubular elongate outer body which is connectable both ends in a drill string. An inner body is enclosed in the outer body and is positioned to form a mud flow annular space between the two bodies. A motor converts mud flow through the annular space into rotational torque. The water drives a shaft which is connected to a hydraulic pump for pumping hydraulic fluid to an elevated pressure. A constricted passage in the annular space is located so that mud flow through the space is directed through the constricted passage. A plug is movably activated by a piston to vary the constriction on the mud flow with movement of the plug. A hydraulic circuit connected to the pump uses hydraulic fluid in conduits through a controllable valve to the piston and cylinder for moving the plug to an altered position to modulate the mud flow and thus form an output signal dependent on the manipulation of the controllable valve. The invention provides a self-contained device which forms the output signals modulated into the mud flow. The device is self-contained in that it generates its own electrical power for operating transducers, and the signal are imposed on a two-position, four-way valve.