Interpretation of fractures and stress anisotropy in Marcellus Shale using multicomponent seismic data

Abstract

Using a data set from the Marcellus Shale, we evaluated the advantages of multicomponent seismic data for fracture and anisotropy studies over conventional P-wave data. Using traveltime and amplitude analysis on pre- and poststack seismic data, we concluded that PS-waves can provide more accurate information about the location, orientation, and intensity of natural fractures and stress anisotropy than P-waves. Our analysis indicated that regional stress was the main cause of velocity anisotropy. Amplitude variation with offset and azimuth appeared to be more useful for fracture studies, whereas traveltime variations (especially PS-waves) provided a better indication of regional stress orientations. Principal directions for amplitudes and traveltimes of PP- and PS-waves were different. Misalignment of PP- and PS-waves principal directions suggested that the simplest, most realistic anisotropy model for the fractured Marcellus is monoclinic symmetry.