Quantitative characterization and optimization of fracability in continental shale reservoirs

Recent exploration has confirmed the potential of Jurassic continental shales in the Sichuan Basin, yet hydraulic fracturing quality remains a key challenge for their commercial development. This study establishes a quantitative model to evaluate and optimize shale fracability, with application to Middle-Lower Jurassic shales in the Yuanba area. The gas-generation potential, storage capacity, and reservoir characteristics of the Qianfoya Formation and Da'anzhai Member were analyzed. Brittleness index, horizontal principal-stress difference coefficient, and fracture toughness were identified as the main controlling factors, representing the material basis, fracture initiation difficulty, and propagation capacity, respectively. These parameters were integrated into a unified fracability index using normalization and Analytic Hierarchy Process (AHP) weighting. Results show that Jurassic continental shales generally have lower fracability than marine shales, with the Qianfoya Formation outperforming the Da'anzhai Member. We suggest prioritizing the Qianfoya Formation for development and adopting stereoscopic exploration strategies to enhance shale oil and gas recovery.