Seismic Reservoir Characterization in Resource Shale Plays: Stress Analysis and Sweet Spot Discrimination

Alexis Ferrer
Senior Reservoir Geophysicist, Team Leader—Open Center Reservoir Characterization Group, Hampson- Russell, Software & Services, a CGGVeritas Company

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 correlate to lithology, rock strength and stress fields in the formation. Knowledge and proper utilization of these attributes may prove valuable in the optimization of drilling and completion activities. In this paper 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 may 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 valuable during the completion stage of the fracture stimulation process. The reliability of these estimates has been addressed by incorporating triaxial core measurements. We also provide relative production estimates by combining geomechanical and stress properties to estimate porosity, shale and carbonate content, and water saturation. Our goal is to ultimately use these volumes in a predictive mode for proper well placement and completion practices.

AAPG Search and Discovery Article #90165©AAPG 2012 GEOSCIENCE TECHNOLOGY WORKSHOP, 2-4 December 2012, Buenos Aires, Argentina