Evaluating Hydraulic Fracturing in Cased Holes With Cross-Dipole Acoustic Technology

Abstract

A cross-dipole technology was used to evaluate a carbonate formation in southeastern New Mexico to determine fracture trends in a waterflooded environment. The measurements were first made in open hole, then in cased hole before and after fracture stimulation. The cross-dipole data were processed to find the amount of shearwave anisotropy and the associated azimuth. The results demonstrate that stimulated fractures create a substantial anisotropy and a well-defined azimuth behind casing. More important, by evaluating the anisotropy magnitude and azimuth from the cased-hole data, we can determine the fracture extent along the borehole and its azimuth in the formation. The fracture extent is also consistent with that from a radioactive tracer measurement. The results of this study suggest that cross-dipole acoustic logging is an effective technology for cased-hole fracture stimulation evaluation.

Seismic Shear Wave Anisotropy in Cracked Rocks and an Application to Hydraulic Fracturing

“…The above theory and analysis have been applied to interpret hydraulic fracturing results from shear wave anisotropy measurements acquired in two wells. Shear wave anisotropy measurements using a four‐component (4C) dipole logging tool are commonly used for hydraulic fracturing evaluation (Tang et al, ). This tool measures a fast and a slow shear wave velocity from 4C waveform data, from which azimuthal shear wave anisotropy is determined (Tang & Chunduru, ).…”

Assessing rock brittleness and fracability from radial variation of elastic wave velocities from borehole acoustic logging

“…The result of the fracturing operation was evaluated using the before and after fracturing cross‐dipole shear‐wave anisotropy measurements, a commonly used borehole acoustic technique for hydraulic fracturing evaluation (Tang, Patterson, and Hinds ). The comparison of the cross‐dipole shear‐wave anisotropy before (left shaded curve) and after (right shaded curve, obtained from post fracturing logging) fracturing the reservoir is shown in Panel 7.…”