New study of etching patterns of acid-fracture surfaces and relevant conductivity

摘要

AbstractAcid fracturing is a well-stimulation process in which the dissolution of formation rocks results in unevenly etched fracture surfaces that create lasting conductivity after fracture closure. Acid-fracture conductivity strongly depends on the geometric characteristics of the fracture surface, which has previously been described and defined as consisting of the following four patterns: uniform, rough, channel, and tensile. However, this method for classifying the etching patterns is still qualitative and not sufficiently detailed for characterizing the fracture surface and studying the conductivity. This study focuses on the etching pattern and conductivity of the fracture surface. Using a laser profilometer to scan the rough surface of an acid-etched fracture, the geometric characteristics of the rough surface were analysed. On the basis of the analysis, four new parameters were defined to characterize the structure of the rough surface. A digitalized method with the new parameters was used to classify the acid-fracture surface into 9 etching patterns, providing a quantitative characterization method that produces more detailed results than have previously been attained. Finally, some experiments were conducted to study the relationship between the fracture conductivity and etching patterns.Highlights?New parameters defined to characterize the structure of acid channels.?A digitalized classification method is presented to classify acid etching patterns.?Relationship between conductivity and the etching patterns have been discussed.]]>