Downhole deep transient measurements with improved sensors

摘要

Systems, devices, and methods for evaluating an earth formation. Apparatus include an electrically conducting tubular; at least one transmitter configured to propagate an electromagnetic field in the earth formation; and at least one receiver configured to receive an electromagnetic signal resulting from interaction of an electromagnetic field with said earth formation. The at least one transmitter and at least one receiver may employ antenna assemblies comprising: a recess in the conducting tubular defined by at least one radially extending surface substantially perpendicular to a longitudinal axis of the conducting tubular and non-radially extending surfaces; an antenna in the recess; and conductive shielding, the conductive shielding having a conductivity significantly more than a conductivity of the conducting tubular and covering the whole of each of the plurality of radially extending surfaces.