Shale Fracturing Interval Optimization Based on Comprehensive Evaluation of Fracability and Heterogeneity

Reservoir stimulation is a critical technique for achieving effective production enhancement in shale formations, with rock mechanics analysis serving as the foundation for realizing stimulated reservoir volume (SRV). However, the stimulation effectiveness is significantly influenced by the strong heterogeneity of shale. Based on well-logging data, this study quantitatively characterizes the fracability and heterogeneity of the Wufeng-Longmaxi Formation shale in the Sichuan Basin, establishes an optimized fracturing interval selection method, and validates the results through comparisons with microseismic data and production performance from actual fracturing stages. The results show that brittleness index and fracture development index exhibit strong positive correlations with SRV. Higher mechanical brittleness indices correlate with wider fracture apertures and reduced breakdown pressures. Fracture toughness and horizontal stress difference coefficient are negatively correlated with stimulated reservoir volume. Strong mechanical heterogeneity will cause difficulties in fracturing operation, and the fracture after fracturing is difficult to scale; Permeability heterogeneity is negatively correlated with the productivity of each fractured section, which makes gas migration and production difficult and makes it difficult to fully mobilize reserves. Based on the common constraints of fracability index model and heterogeneity evaluation model, the comprehensive optimization of shale reservoir is carried out, which is well verified by comparison with microseismic data and fracturing operation curve of well L-1X and well L-3X, and this method can provide theoretical guidance for fracturing operation design in the future.