A novel mineral composition inversion method of deep shale gas reservoir in Western Chongqing

Abstract

Abstract The mineral composition of shale gas reservoir is complex and diverse and a universal mineral composition model is not available. In this study, the organic framework was introduced to construct petrophysical volume model of double skeleton mineral components in a sample of shale gas reservoir from Western Chongqing. This was done considering the XRD of core and thin section analysis. The volume contents of organic- and inorganic-skeleton mineral components in the shale gas reservoir were calculated with the least squares-singular value decomposition optimization inversion method based on the three porosity curves (AC, DEN and CNL) correction by argillaceous and kerogen volume content. This optimization inversion method was done using the XRD of core as the convergence condition. The calculation results showed that the correlation coefficient R2 between the mineral volume content calculated with the optimized inversion method and the X-ray diffraction measurement results was between 0.80 and 0.89, which was higher than those of the multiple regression model based on core data and the interpretation result of element capture spectrum logging (ECS) data. The novel model had been verified and applied in several wells, displaying the wide application potential since only need conventional logging data. The study provides a solid basis for the accurate evaluation of deep shale gas reservoirs.