Measuring while drilling employing cascaded transmission systems

摘要

A measuring while drilling assembly utilizes two transmission channels connected in cascade in order to transmit a signal of a sensed downhole condition from a location near a downhole drill bit to a surface receiver. A first transmission channel has its downhole end connected to a first signal generator and its uphole end connected to a second signal generator. The second signal generator includes a pulser. A second transmission channel has its downhole end connected to the pulser and its uphole end connected to a pressure transducer at the surface of the earth.