Patent ID: 8332152
Filing Date: 2012-12-11
Classification: G01V

Abstract:
1. A method of conducting drilling operations in an earth formation, the method comprising: conveying an electromagnetic instrument in a borehole in the earth formation; changing a current through a transmitter on the electromagnetic instrument and inducing a current in the earth formation; receiving a first temporal signal resulting from the induced current in a first receiver on the electromagnetic instrument, the received first temporal signal including an effect of a conductive body of the electromagnetic instrument; receiving a second temporal signal resulting from the induced current in a second receiver on the electromagnetic instrument, the received second temporal signal including the effect of the conductive body of the electromagnetic instrument; and using the first temporal signal, the second temporal signal, and a ratio between a first reference signal and a second reference signal for estimating a distance to an interface in the earth formation, wherein estimating the distance comprises: