Geophysical Evaluation Technology for Shale Gas Reservoir: A Case Study in Silurian of Changning Area in Sichuan Basin

Abstract

Shale gas belongs to unconventional natural gas; it has many reservoir evaluation parameters hard to evaluate. Accurate calculation of parameters and comprehensive evaluation of favorable blocks are critical for geological evaluation, well deployment and reservoir reconstruction of shale gas. After research of Silurian Longmaxi Formation in Changning area in Sichuan Basin a petro physics model for shale gas reservoir is established through a large number of core data analysis and a calculation method for reservoir critical parameters is established through logging data. Based on logging results, the sensitivity analysis indicates that Vp/Vs is the most optimally sensitive parameter for shale gas reservoir identification and evaluation. The thickness, the total organic carbon content, the total gas content and the brittleness index of shale gas reservoir are realized by pre-stack simultaneous inversion technology. The reservoir classification standard is established, then the comprehensive evaluation for shale gas is achieved. There is a high consistency between evaluation results and actual drilling results, so the geophysical evaluation technology for shale gas reservoir can effectively guide well deployment and horizontal well drilling design and can provide technical support for efficient development of shale gas.