Optimum Logging Interpretation of Multi-mineral Model for Complex Shale Gas Reservoir - A Case Study of Devonian Shale Gas in WCSB

Abstract

Complex petrology, mineralogy and reservoir physical properties created by the sedimentary environment determine the complexity and multiplicity of shale gas reservoir logging interpretation and increase uncertainty of shale gas development. Considering the complexity of shale gas reservoirs and the accuracy requirements of shale gas development, this paper analyzes the petrology and mineralogy of shale gas reservoirs based on thin section identification, XRD analysis and different mineral logging responses, establish a multi-mineral model of shale gas reservoir based on material balance equation. Based on the multi-mineral model, the nonlinear weighted least squares algorithm is used to construct the shale gas reservoir optimized logging interpretation objective function based on the clay, mineral and fluid logging error analysis of multi-mineral model. The variable scale method is used to solve optimized logging interpretation objective function to achieve multi-mineral model optimization logging interpretation of complex shale gas reservoirs. In the Devonian shale gas reservoir application in the West Canadian Sediment Basin, the relative error between the optimal interpretation result and the core analysis results is between 3.5% and 7.3%, with an average of 5.8%. The average relative of theoretical and measured values of the logging is 8.5%, which reflects the accuracy and practicability of the multi-mineral model optimized logging interpretation of complex shale gas reservoirs, and shows the wide application prospects in practical applications.