Seismic characterization of reservoirs with variable fracture spacing by double focusing Gaussian beams

Abstract

Fractured reservoirs account for a majority of the oil production worldwide and often have low recovery rate. Fracture characterization is important in building reservoir flow models for enhanced oil recovery. Information about fracture orientation, fracture spacing, and fracture compliances is essential. When a fracture network consisting of multiple sets of fractures with variable fracture spacing/orientation is present, we have to determine the spatial information about them as this may represent important connectivity information for fluid flow. We present a seismic method that can achieve the above goals in the context of seismic scattering, when the fracture spacing is on the order of half of the wavelength. The method is based measuring the beam interference pattern for two Gaussian beams focused on a fractured reservoir location, one beam from the sources and the other from the receivers. Numerical examples show that our method can provide spatially dependent information on fracture parameters.