On the detectability and appraisal of hydraulic fractures in layered media using borehole resistivity measurements

Hydro-fracturing is a widely used technique to enhance hydrocarbon production from organic shales and tight-gas sands. To assess the flow efficiency in the treated area, the geometrical properties of induced fractures, including their location, orientation, and size, must be determined. Recent simulation results show that low-frequency borehole resistivity measurements are promising candidates for detecting fractures, especially when they are injected with electrically conductive proppant that increases the conductivity contrast between the fracture and the background (D. Pardo and C. Torres-Verdin, SEG Expanded Abstracts, 2012; K. Yang et al., SEG Expanded Abstracts, 545–550, 2013; K. Yang and A. E. Yılmaz, IEEE APS Int. Symp., 2013). These and similar studies, however, assume that the fracture resides in a homogeneous and isotropic background. It is necessary to quantify the validity of this method for detecting more general fractures, including the common case of irregularly-shaped, arbitrarily-oriented fractures in the presence of multiple layers, anisotropic layers, and mechanically weak surfaces.