强非均质性储层CO2增能压裂裂缝扩展规律数值模拟OA

To address the challenges of poor sweep efficiency of injected media and unpredictable fracture propagation behavior in traditional energy-replenishment development and fracturing stimulation for reservoirs characterized by water sensitivity,low-permeability,and strong heterogeneity,a three-dimensional fine reservoir numerical model with strong heterogeneity was established based on the Rarefed-Leap-frog(R-L)coupling method,and the degree of reservoir heterogeneity was quantified using indicators such as permeability contrast and porosity variation coefficient.By comparing the stimulation performance of hydraulic fracturing,CO2-enhanced fracturing,and N2 fracturing,and incorporating CO2 dissolution effects,the influence patterns of geomechanics p arameters on fracture propagation was clarified and the mechanism of CO2-enhanced fracturing was determined.The results indicate that CO2-enhanced fracturing exhibits optimal adaptability for such reservoirs,creating more complex fracture networks and yielding the maximum stimulated reservoir volume(SRV).However,CO2 dissolution effects are predominantly negative:weakly acidic fluids induced by CO2 dissolution aggravates clay mineral swelling,resulting in a significant near-wellbore permeability decline that partially offsets the positive energy-enhancement effects.A higher Young's modulus promotes longer fracture propagation,yet the incremental gain in SRV tends to slow down beyond a certain threshold.In contrast,a higher Poisson's ratio reduces SRV and simplifies fracture morphology.Numerical simulations specific to the target block further demonstrate that fractures propagate more easily in regions where Young's modulus is≥18.75 GPa and Poisson's ratio is≤0.22.Moreover,when the permeability ratio is≥1.5 and the in-situ stress coefficient of variation is≥0.25,SRV decreases by over 20%.These findings provide technical guidance for CO2-enhanced fracturing operations in horizontal wells within analogous reservoirs.