Fracture development characteristics in carbonate reservoirs: insights from stress field simulation with a heterogeneous rock mechanics model and adaptive boundaries

Tectonic fractures serve as critical storage and flow pathways in carbonate reservoirs, with their development directly governing hydrocarbon enrichment and fluid migration. However, prediction accuracy is often limited by the simplified treatment inherent in traditional homogenized models, hindering the exploration of deep carbonate reservoirs. To fill this gap, this study innovatively constructs a 3D heterogeneous rock mechanics model coupled with an adaptive boundary constraint algorithm, and applies it to the Ordovician fractured reservoirs in the deep coverage area of the Tahe Oilfield, Tarim Basin. High-precision paleo-stress field simulations were conducted for three key tectonic periods (Middle Caledonian, Early Hercynian, and Neotectonic), significantly improving the accuracy and objectivity of stress field characterization. Fracture development intensity is quantitatively predicted based on rock failure criteria and validated against core observations and production data. The results demonstrate that: (1) The heterogeneous rock mechanical model coupled with adaptive boundary conditions significantly improves the reliability of stress field simulations. (2) Fracture development exhibits a strong correlation with the paleo‑stress field, with fractures predominantly concentrated around fault peripheries, tips, and intersections. (3) Fracture intensity shows a pronounced positive correlation with both the horizontal stress difference (∆σ_h) and the stress heterogeneity coefficient (k) under the geological conditions of the study area; this correlation statistically tends to strengthen once these parameters exceed certain thresholds identified by segmented regression. (4) Predicted fracture linear density matches well with cumulative oil production from individual wells, confirming that the fracture system is a key controlling factor for hydrocarbon enrichment in deeply buried carbonate reservoirs. This study provides a robust methodological framework and practical guidance for quantitative fracture prediction and efficient exploration in carbonate reservoirs. This study provides a robust, repeatable method for quantitative fracture prediction and offers important guidance for the efficient exploration and development of deep carbonate reservoirs worldwide.