水力裂缝形貌对酸刻蚀行为及导流能力影响

目前酸压裂缝导流能力实验多采用光滑岩板模拟地层水力裂缝，忽略了裂缝粗糙形貌对酸刻蚀行为、导流能力影响。采用自研装置"酸压裂缝导流能力测试系统"，分别用光滑岩板、粗糙岩板模拟光滑裂缝、粗糙裂缝，研究了不同注酸排量、注酸时间下两种不同形貌水力裂缝的酸刻蚀行为和导流能力特征。结果表明，酸刻蚀后光滑裂缝轮廓线迂曲度增加；粗糙裂缝相反，酸刻蚀作用体现为削"峰"深"谷"。增加注酸排量或注酸时间，粗糙裂缝的高程变化、裂缝宽度、酸溶蚀量和导流能力增加幅度均明显大于光滑裂缝，且导流保持能力更好；粗糙裂缝对注酸参数变化更敏感。粗糙岩板利于真实评价储层条件下酸压裂缝导流能力，提高酸压方案设计的针对性，改善酸压效果。

Effects of Morphology of Hydraulic Fractures on Acid Etching Behaviors and Fluid Diversion Capacity

At present, most simulations of hydraulic fractures are conduced based on the assumption of smooth parallel plates, ignoring the effects of the morphology of the fractures on acid etching behaviors and fluid diversion capacity. A self-developed device named "acid pressure test system for fracture fluid diversion" was used to simulate smooth and rough fractures, respectively, with smooth and rough plates to study the characteristics of acid etching behaviors and diversion capacity of the two types of fracture morphology with different acid injection volumes and periods. The results show that the tortuosity of the fracture profile increased after acid etching for smooth fractures, whereas the opposite was observed for rough fractures, as acid etching reduced the peaks and deepened the troughs. Increasing the acid injection volume or period led to significantly larger change in elevation, fracture width, acid dissolution amount, and diversion capacity for rough fractures than for smooth fractures, whereas the former had not only better retention ability of fluid diversion, but also higher sensitivity to changes in acid injection parameters. In conclusion, the assumption of rough plates is beneficial for realistically evaluating the diversion capacity of acid pressure fractures under reservoirs, thus improving the targetedness of the acid pressure scheme design and the acid pressure effect.