Seismic Reservoir Characterization in Unconventional Shale Plays

Surface seismic data has proven to be an invaluable asset for organizations producing hydrocarbons from unconventional resource plays. Initially, one of the primary benefits of surface seismic was the ability to locate and avoid drilling into zones with faults, fractures and karsting which adversely affected the ability to complete the well successfully. More recent advances in pre-stack seismic data analysis yield attributes that appear to be correlated to formation lithology, rock strength and stress fields. Knowledge and proper utilization of these attributes may prove valuable in the optimization of drilling and completion activities. In this article we show an integrated seismic approach based on pre-stack azimuthal seismic data analysis and well log information to identify “sweet spots”, estimate geomechanical properties and in-situ principal stresses. Properties such as Young’s Modulus and Poisson’s Ratio provide valuable information for facies identification, mineral content, and rock strength. From these, we may infer preferential drilling locations or “sweet spots”. Additionally, analysis of differential horizontal stress may be calibrated to field observations yielding stress field predictions such as fracture initiation pressure and closure pressure which are valuable during the completion stage of the fracture stimulation process. The reliability of these estimates has been addressed by incorporating triaxial core measurements (Jaeger J et al., 2007; Warpinski, N. and Smith, M.,1989). Relative production estimates can be derived by combining geomechanical and stress properties by estimating porosity, volume of shale, carbonate content, and water saturation. The goal is to ultimately use these volumes in a predictive mode for proper well placement and completion practices.