Pacific Section AAPG, SPE and SEPM Joint Technical Conference

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The Investigation Of An Integrative Approach For Fracture Density Inversion Using AzAVO Analysis


Understanding the spatial distribution of fracture is important for identification of reservoir zones with higher production potential. Furthermore, knowledge of distribution of natural fracture network could be helpful in the design of appropriate stimulation jobs such as multi-stage hydraulic fracturing. Azimuthal Amplitude Variation Versus Offset of seismic data (AzAVO) is a common measure of anisotropy which is often analyzed with the purpose of fracture detection and characterization. Determining fracture properties such as spatial distribution, orientation and whether they are open or close, from AzAVO data is an inverse problem. This could be addresses using model-based inversion techniques. Common methods for fracture density inversion from pre-stack gathers are illustrated by constructing a set of optimal basis functions through singular value decomposition. The general workflow of inverting for multiple seismic attributes is presented with a simple synthetic fracture density mapping case of multi-azimuth common-middle-point gathers. Further complementation of AVO anisotropy attributes with geological information and other anisotropic attributes is then considered with the purpose of better interpreting the attributes and reducing the level of uncertainty in such problems. Integrative approaches are investigated for combining AzAVO anisotropy with attributes such as travel-time anisotropy and shear-wave anisotropy and frequency absorption attributes.