An apparatus and method for minimizing the effects of a common mode voltage signal in downhole logging tools utilized to determine the resistivity of an adjacent portion of a borehole wall. Two current electrodes are energized by an excitation source to create an oscillatory electric field in a borehole wall. A voltage drop across a segment of the borehole wall is measured by two voltage electrodes, and the differential voltage is used in combination with a measured current flow to determine a resistivity value for the borehole wall. A common mode voltage in front of the two voltage electrodes is measured and minimized by controlling the excitation source, thereby reducing the resistivity measurement error.
申请公布号
WO2007055790(A3)
申请公布日期
2009.05.22
申请号
WO2006US34959
申请日期
2006.09.08
申请人
HALLIBURTON ENERGY SERVICES, INC.;GOODMAN, GEORGE, D.;HARRIS, EDWARD, J., III