Method of eliminating conductive drill parasitic influence on the measurements of transient electromagnetic components in MWD tools

摘要

A transmitter on a bottomhole assembly (BHA) is used for generating a transient electromagnetic signal in an earth formation. A receiver on the BHA receives signals that are indicative of formation resistivity and distances to bed boundaries. The transmitter and receiver may have axes that are parallel to or inclined to the axis of the BHA. The transmitter and the receiver are on a tubular on a damping portion of the BHA that includes cuts for attenuating eddy currents. The damping portion may include non conducting material such as a ferrite on the outer surface.