Unreliable determination of in situ stress orientation by cross multipole array acoustic logging in fractured shale reservoirs

With the development of shale gas exploration in China, use conventional logging tools has been introduced, and cross multipole array acoustic have gradually used to determine stress orientation shale. The direction fast shear waves (FSWs) is generally parallel horizontal maximum principal compression (SHmax). However, azimuth FSWs found be main strike (but not SHmax) structural fractures reservoirs. Outcrop image data indicate that natural this area NE‒SW. If wave anisotropy caused by only around borehole are known NE‒SW, SHmax should NE‒SW; however, according statistics land movement adjacent areas, anelastic strain recovery, earthquake focal mechanism, breakouts, hydraulic fracturing data, deviated well drilling-induced fracture local regions, oriented NW‒SE direction, directions direction. This contradiction indicates may affect FSWs. Therefore, it reliable XMAC (Cross-Multipole Array Acoustilog) situ fractured In addition, middle thick mudstones NW‒SE, which represent accurate information about