Patent ID: 6377050
Filing Date: 2002-04-23
Classification: G01V

Abstract:
A method of measuring the resistivity of a material, comprising the steps of:providing a drill collar with at least two transmitters and at least two receivers proximate the material, the transmitters and the receivers being aligned and the receivers surrounding the transmitters; transmitting a first electromagnetic wave train into the material using a first one of the transmitters; recording first electromagnetic signals sensed by the receivers in response to the first wave train, and recording a first phase difference between a pair of outermost receivers for the first wave train; transmitting a second electromagnetic wave train into the material using a second one of the transmitters; recording second electromagnetic signals sensed by the receivers in response to the second wave train, and recording a second phase difference between said pair of outermost receivers for the second wave train; and estimating the resistivity of the material using the first and second electromagnetic signals.