Successful production from unconventional reservoirs requires expensive hydraulic fracturing operations that are not only costly but pose environmental and health risks if not managed properly. Optimized use of microseismic imaging is essential to control the hydraulic fracture operation, to minimize any possible environmental hazards introduced by fracturing, and to achieve cost efficiency.
An integrated workflow that incorporates advanced geophysical techniques is presented in this paper to enhance microseismic imaging of hydraulic fracturing in unconventional resources in Saudi Arabia. The use of surface seismic attributes is suggested to primarily minimize location uncertainties of microseismic events; whether downhole or surface receivers arrays were used. Secondly, coherence and edge attributes are used to highlight faults and seismic-scale fractures in seismic volumes, knowledge of which may favorably infer the "geomechanical" maximum horizontal stress direction; hence the main direction of fluid flow within targeted sediments and a preliminary conception of hydraulically induced fractures' direction of propagation. Moreover, knowledge of fault networks in reservoirs is vital to pinpoint potential barriers that may impact the growth of fractures, and their likely geometries.
Seismic attributes are combined with acoustic impedance inversion volumes, Vp/Vs and Poisson ratios to further enhance inferences to hydrocarbon bearing, and sediment brittleness. These methods can be used collectively to optimize multi-staged hydraulic fracturing of unconventional reservoirs, which will eventually lead to limiting stimulation to only selected "producible" sweet spots, thus minimizing the required number of "fracking" stages and associated environmental and financial concerns. These methods should also drive the use of more economic stimulation solutions using low-proppant, high-flow-rate, and water based treatments (Gale, et. al., 2007).