基于裂缝重构评价酸蚀对碳酸盐岩应力敏感性的影响

碳酸盐岩的脆性较强,应力敏感性实验会对岩心产生不可逆破坏,导致无法利用同一岩心评价酸蚀前后的应力敏感性差异,评价结果对比性较差.针对该问题,基于裂缝重构技术建立了一套评价酸蚀对碳酸盐岩应力敏感性影响的方法,对酸蚀前后的裂缝缝面进行特征扫描并重构,利用有限元方法开展了有效应力作用下裂缝闭合规律的研究,并模拟了有效应力下酸...

Evaluation of the Effect of Acid Erosion on Stress Sensitivity of Carbonate Rocks Based on Fracture Reconstruction

Carbonate rocks are highly brittle and stress sensitivity test will lead irreversible damage to the cores,resulting in the inability to evaluate the difference in stress sensitivity before and after acid erosion with the same cores and the poor comparability of evaluation results.To address this challenge,a method to evaluate the effect of acid erosion on stress sensitivity of carbonate rocks was established based on fracture reconstruction technology,the fracture surfaces before and after acid erosion were characteristically scanned and reconstructed,the finite element method was applied to study the fracture closure pattern under effective stress,and the effect of acid erosion on fracture seepage under effective stress was simulated to evaluate the variation in fracture permeability.It was found in the study that the difference in mineral components on the fracture face leads to non-uniform acid erosion on the fracture surface,making the fracture surface more rough and resulting in greater difference in the fractal dimension between the fracture surfaces;under the effective stress of 40 MPa,before the acid erosion,the fracture width decreased by more than 55%and the permeability damage rate was greater than 90%;however,after the acid erosion,the fracture width decreased by less than 40%,the permeability damage rate was less than 75%,and the stress sensitive damage decreased.In other words,acid fracturing and pickling are conducive to improving the permeability of artificial fractures and prevent fracture closure.This study can provide a reference for the evaluation of stress sensitivity damage of fractured tight sandstone and shale reservoirs.