ELECTROMAGNETIC AND MAGNETOSTATIC SHIELD TO PERFORM MEASUREMENTS AHEAD OF THE DRILL BIT

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. A combination of electromagnetic shielding and magnetostatic shielding enables determination of distance to an interface ahead of the drillbit.