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US 9,540,922 B2Granted
Electromagnetic method for obtaining dip azimuth angle
AssigneeSchlumberger Technology Corporation
InventorsXiaoyan Zhong, Gerald N. Minerbo, Steven F. Crary
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Abstract
An electromagnetic method for obtaining a dip azimuth angle from downhole electromagnetic measurements includes acquiring electromagnetic measurement data in a subterranean borehole from at least one measurement array. The electromagnetic measurement data is processed by a least squares method to obtain the dip azimuth angle. Related systems and apparatuses are also disclosed herein.
Claims13
A method for computing a dip azimuth angle from downhole electromagnetic measurements, the method comprising:
- (a) placing an apparatus to conduct electromagnetic measurements in a subterranean borehole such that the apparatus is positioned next to a formation of interest;
- (b) applying one of a time varying electric current and a time varying alternating current to at least one antenna in the apparatus;
- (c) acquiring a plurality of voltage measurements at a corresponding plurality of measurement arrays deployed in the subterranean borehole, wherein the arrays are placed within the apparatus;
- (d) causing a processor to process the voltage measurements acquired in (a) to obtain least squares complex fitting coefficients defined by a preset voltage measurement equation at a receiving antenna for the apparatus;
- (e) causing the processor to process the least squares complex fitting coefficients to obtain the dip azimuth angle by minimizing a weighted average of squares of the plurality of voltage measurements;
- (f) transmitting the obtained dip azimuth angle to a surface location;
- and
- (g) plotting the dip azimuth angle versus a borehole depth at which the dip azimuth angle was calculated.
5 more elements
Dependencies are inferred from the claim text.