AVA analysis and modeling of multi-component seismic wave modes (P-P, P-SV and SV-P): Wolfberry Play Midland Basin, Texas

Abstract

In this study, amplitude variation with angle (AVA) of different seismic wave modes, P-P, P-SV and SV-P, will be evaluated. AVA analysis can provide important information about reservoir rocks such as lithology, porosity, and pore fluids that can be used to reduce hydrocarbon exploration risk. P-P AVO analysis has become a common practice in oil and gas exploration industry specifically in offshore areas such as Gulf of Mexico, North Sea, and West Africa. Because P-SV AVO has no practical way to evaluate large 3D pre-stack seismic data sets as in P-P AVO (Intercept (A) and Gradient (B) cross-plotting method) analysis, it is not very common in industry use. Because SV-P wave mode is a new research area in seismic community and by all means, there has been no work about SV-P AVO/AVA analysis in the geophysics literature, this thesis represents a pioneer study. Real seismic data from the Wolfberry unconventional reservoir play of the Midland Basin which consists of sandstone and limestone lithologies as a mixture of different amounts, manually created synthetics, synthetics created with well log data, and real brine and gas sand points from Castagna and Smith (1994) were employed in this investigation of AVA attributes. viii Generally, AVA analysis works for high-porosity and gas-saturated rocks. Because the Wolfberry unconventional reservoir play is oil prone and composed of low-porosity formations, by P-P AVA analysis, I rarely found gas influence or higher porous rocks in my database. Similar to Gonzalez’s (2000) “E” attribute from P-SV AVO, a new “E” attribute is found from SV-P AVA analysis. Both “E” attributes were investigated with 25 shale to brine and shale to gas sand points. Not only “E” attribute for P-SV but also new “E” attribute for SV-P reflectivity provided sound lithology and pore fluid discrimination.