Rock Physics and Mechanical Stratigraphy of the Woodford Shale, Anadarko Basin, Oklahoma

Abstract

Application of seismic techniques in exploration of mudrocks is limited due to the lack of well-developed rock physics methods that can link the matrix and fluid properties to seismic velocities. We present a first principle based modeling method for predicting P- and S- wave velocities (VP and VS respectively) in mudrocks accounting for the effect of silica content, porosity, and free gas saturation. We apply the modeling method to real VP - VS data from the Woodford Shale of the Anadarko Basin in the Mcneff 2-28 well, section 28, T.10N., R.6W., Grady County, Oklahoma to estimate the rock and fluid properties. Modeling suggests that the Woodford within the Mcneff 2-28 has high silica content (>60%), intermediate porosity (10 - 20%), and high gas saturation (90-85%). Although our estimate of gas saturation has uncertainty, estimated porosity and silica content are reasonable when compared to a suite of logs from the Mcneff 2-28 and a core from the Campbell 1-34, section 34, T.10N., R.6W., Grady County, Oklahoma (~1 mile SE of the Mcneff 2-28). We conclude that the Upper Woodford unit in the Mcneff 2-28 locality is potentially prospective.