Multicomponent 3D seismic interpretation of the Marcellus shale Bradford County, Pennsylvania
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Abstract
High spatial variability of petrophysical and petrochemical properties of the Marcellus formation was reported by Hill et al. (2002). This creates a major challenge in reservoir characterization with conventional seismic data. An investigation into the potential of integrated compressional P-wave and converted-wave seismic interpretation, to help characterize geological properties of the Devonian Marcellus shale, has been conducted based on the 3C- 3D data set acquired. Synthetic and real seismic data have been used to conduct this evaluation. Interval Vp/Vs analysis has been performed and the Poisson’s ratio was generated to map lateral changes in lithology and rock properties. Sweet spots are interpreted to area with high quartz, an anomalous low Vp/Vs. The Vp/Vs Marcellus map shows the lateral lithological variability and therefore brittle areas. An inversion was run for the compressional P and the converted PS sections to examine the anomalies observed within the Vp/Vs map. The anomalies distinguished within the Vp/Vs map were noticeable in the inversion sections. The inversion was followed by a seismic attribute analysis to understand the distribution of fractures. The curvature and the coherency attributes delivered highly fractured area and major faults. This study documents the results of an integrated workflow of seismic interpretation, seismic inversion and seismic attribute analysis. It illustrates the potential of the Vp/Vs analysis to discriminate between shale-rich and sand-rich material and the ability of the curvature and coherency attribute to potentially highlight zones of intense fracturing.