ABSTRACT

The capability of a multicomponent induction measurement to detect fractures around boreholes is studied using both numerical simulation and field data analysis. With examples given for hydraulically induced fractures, our numerical simulation shows that coplanar-coil induction measurements (σxx and σyy, where the x-axis is parallel to and the y-axis is perpendicular to the fracture plane provide unique value for detecting the fractures that a coaxial-array measurement (σzz does not have. For a resistive fracture, σxx is much more sensitive to shallow fractures than σzz. In contrast, if a fracture is filled with materials more conductive than the surrounding formation, only the σyy measurement can provide information about the existence of the fracture. Field data from a Gulf of Mexico well dilled with oil base mud shows the capability of the multicomponent induction measurement, especially σxx and σyy, to detect hydraulic fractures. The existence of the fractures is confirmed independently by crossed-dipole acoustic and Stoneley wave measurements. The crossed-dipole acoustic and multicomponent induction measurements are further combined to jointly characterize the fractures. More specifically, the crossed-dipole acoustic measurement is used to determine the fracture azimuth, and the difference between the σxx and σyy induction measurements is applied to estimate the fracture length using the fracture azimuth as an input.

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