蓬莱天然气区酸蚀裂缝导流能力实验研究

Experimental Study on the Conductivity of Acid Etching Cracks in Penglai Gas Area

采用蓬莱天然气区沧浪浦组和茅口组碳酸盐岩全直径岩心,钻取和剖切标准岩心构建缝宽1 mm裂缝进行室内实验,分析了不同酸压工艺对壁面溶蚀效应的影响,分析了酸液类型、酸液用量、注入级数以及闭合压力对酸蚀导流能力与导流能力衰减率的影响规律,并评价了不同溶蚀壁面粗糙度值对导流规律的影响。研究结果表明:相比单一酸液1级交替注入,自生酸和胶凝酸组合具有更强的溶蚀效应,非均匀刻蚀程度和酸蚀导流能力更大。对比不同液量的自生酸和胶凝酸组合3级交替注入,随胶凝酸液量的增加,非均匀刻蚀程度增大,初始导流能力增大,初始导流能力衰减率减小;随自生酸液量的增加,非均匀刻蚀程度增大,初始导流能力减小,初始导流能力衰减率增大;随粗糙度值增大,初始导流能力增大,初始导流能力衰减率增大。随闭合压力增大,胶凝酸用量越多和自生酸用量越少,始终保持更大的导流能力。因此该研究成果在优化酸化压裂施工设计和提高现场施工效果方面具有一定的参考价值。

The full-diameter carbonate cores of Canglangpu Formation and Maokou Formation in Penglai gas area were used to drill and cut fractures with a width of 1 mm in the standard core construction joints for indoor experiments,and the influence of different acid compression processes on the dissolution effect of the wall was analyzed,the influence of acid type,acid dosage,injection stage and closing pressure on the decay rate of acid erosion conductivity and conductivity was analyzed,and the influence of different dissolved wall roughness values on the conductivity law was also evaluated.The results show that compared with the one-stage alternating injection of a single acid,the combination of autogenic acid and gelling acid has a stronger dissolution effect,and the degree of non-uniform etching and acid etching conduction capacity are greater.Compared with the 3-stage alternating injection of autogenous acid and gelling acid combination with different liquid volumes,with the increase of gelling acid liquid,the degree of non-uniform etching increases,the initial conductivity increases,and the decay rate of the initial conductive capacity decreases.With the increase of the amount of self-generated acid,the degree of non-uniform etching increases,the initial conductivity decreases,and the decay rate of the initial conductivity increases.With the increase of roughness value,the initial conductivity increases,and the attenuation rate of the initial conductivity increases.With the increase of the closing pressure,the more gelling acid and the less autogenic acid are used,the greater the diversion capacity is always maintained.Therefore,the research results have certain reference value in optimizing the design of acidified fracturing construction and improving the on-site construction effect.