Fracture Propagation Simulation and Comprehensive Fracability Evaluation of the Thin Interbedded Tight Sandstone Reservoir: A Case Study of Chunliang Oilfield

Thin interbedded tight sandstone reservoirs in the Chunliang Oilfield are characterized by strong vertical heterogeneity, pronounced interlayer in situ stress interference, and limited vertical hydraulic fracture propagation, which together make the stimulated reservoir volume (SRV) difficult to predict. To address these challenges, this study integrates core triaxial compression tests, true triaxial hydraulic fracturing experiments, and finite-element numerical simulations. The controlling mechanisms of the horizontal stress difference, the elastic modulus contrast between reservoir and barrier layers, interlayer cementation strength, and fracturing fluid viscosity on fracture propagation are systematically investigated. The results show that when the horizontal stress difference is less than 5 MPa and the elastic modulus contrast between reservoir and barrier layers is less than 10 GPa, hydraulic fractures more readily penetrate the interlayer interface and form complex fracture networks. With increasing stress difference or elastic modulus contrast, fractures tend to propagate as single planar fractures or become constrained by barrier-layer shielding. Strong interlayer cementation suppresses fracture extension and reduces the stimulated area, whereas high fracturing fluid viscosity causes the fracture geometry to transform from a long and narrow pattern to a short and wide pattern. On this basis, a comprehensive fracability evaluation model is established by integrating the brittleness of both reservoir and barrier layers and the stress difference within and between layers. Field applications to 12 representative wells in the Chunliang Oilfield show that the comprehensive fracability index is positively correlated with the stimulated reservoir volume. The proposed model can effectively quantify interlayer stress shielding and provides a basis for fracturing layer selection and parameter optimization in the thin interbedded tight sandstone reservoir.