A model for predicting marine shale gas sweet spots based on relative sea-level changes and its application

Abstract

Gas-bearing shales have become a major source of future natural gas production worldwide. It has become increasingly urgent to develop a reliable prediction model and corresponding workflow for identifying shale gas sweet spots. The formation of gas-bearing shales is closely linked to relative sea-level changes, providing an important approach to predicting sweet spots in the Wufeng-Longmaxi shale in the southern Sichuan Basin, China. Three types of marine shale gas sweet spots are identified in the shale based on their formation stages combined with relative sea-level changes: early, middle, and late transgression types. This study develops a prediction model and workflow for identifying shale gas sweet spots by analyzing relative sea-level changes and facies sequences. Predicting shale gas sweet spots in an explored block using this model and workflow can provide a valuable guide for well design and hydraulic fracturing, significantly enhancing the efficiency of shale gas exploration and development. Notably, the new prediction model and workflow can be utilized for the rapid evaluation of the potential for shale gas development in new shale gas blocks or those with low exploratory maturity.