METHOD AND APPARATUS FOR ENHANCED ACOUSTIC MUD PULSE TELEMETRY DURING UNDERBALANCED DRILLING

摘要

A method and system for telemetry through a compressible drilling fluid during underbalanced drilling is disclosed. A reflector (110) is positioned downstream from the gas inlet (84) and causes reflected pressure waves having the same pressure polarity as incident pressure waves. A pressure sensor (92) is positioned below the reflector to sense pressure in the compressible drilling fluid. The reflector (110) can be a fixed orifice plate or an adjustable aperture. A borehole communication system is also disclosed wherein a pair of pressure sensors are positioned on either side of a flow restriction (118) located in the gas conduit leading to the gas injector. The flow restriction can be a valve used to regulate the flow rate of the gas being supplied into the drilling fluid, or it can be separate venturi or orifice plate.