基于高斯分布函数的粗糙面模型与酸蚀裂缝闭合模拟研究OA

After acid fracturing,the fracture surface in carbonate reservoirs develops a rough morphology due to acid etching,which supports the fractures to achieve flow conductivity.Under closure pressure,however,fracture morphology and conductivity change greatly,so that the stimulation effect is impacted.To address this problem,this paper establishes a three-dimensional rough-surface fracture contact-closure model based on Gaussian distribution function,describes the elastoplastic behaviors of rocks by virtue of triaxial mechanical test parameters and Drucker-Prager yield criterion,and analyzes the influences of closure pressure,rock elastic modulus and surface roughness on fracture stress distribution and morphological evolution.The following results are obtained.First,the three-dimensional rough surface model constructed on the basis of Gaussian distribution can effectively describe the real morphology of acid-etched fractures.During fracture closure,the contact zone shows significant spatial heterogeneity,and the contact behavior evolves continuously from local micro-convex contact to multi-point regional contact.Second,nonlinear behavior is obvious in the process of fracture closure.As closure pressure increases,the effective fracture width decreases in stages.The closure process is under the joint control of rock mechanical parameters and closure pressure.Different elastic moduli lead to differences in fracture closure degree and morphological evolution.Third,morphological structure and contact stress distribution under different roughness degrees have a crucial influence on fracture closure behaviors.The multi-point support structure formed at higher roughness degree can diminish local stress concentration,thus reducing the overall fracture closure.In conclusion,this study reveals the microscopic mechanism of acid-etched fracture closure,and provides a theoretical basis for evaluating fracture conductivity and predicting stimulation effectiveness after acid fracturing.