Study On Diversion Capacity Of Acid Fractures Based On Digitized Characterization Of Etch Patterns

Acid fracturing makes the surface etched nonuniformly with acid to create a conductive pathway for reservoir fluids to flow into the wellbor. One of the keys to a successful acid fracturing is the creation of sufficient fracture conductivity, which heighly depends on the geometric characteristics of the etching surface. So, an appropriate characterization of the etching surface and study of the relationgship between the characteristics and the fracture conductivity has great significance to the acid fraturing design. Because of the lack of modern fracture conductivity apparatus and the characterization method for the fracture surface, the study of the influence of acid surfaces characteristics and closure pressure on the fracture conductivity is not systematic and regular enough.This study analysed the geometric characteristics of the rough surface with a digital method and defined some new parameters with physical meaning to characterize the structure of the rough surface. And a digitalized method with the new parameters was provided to classify the etching patterns of acid-fracture surface. Besides, by theoretical analysis and experimentation, this study analysed the fracture width under closure pressure and developped a new model to calculate the fracture conductivity. Finaly, base on the digitalized classifying method of the etching pattern and the numerical simulation of the new conductivity calculation model, this study analysed the influence of different etching pattern on the fracture conductivity and told which etching pattern is positive for initial conductivity and which is positive for lasting conductivity.This study indicates that the parameters with physical meaning are more appropriate for characterizing the acid-frature surface and calculating the conductivity. The conductivity model can get a more accurate result by adopting the contact ratio. In different types of acid surface, the ones with channel show obvious advantages both in the initial and final conductivity.The results of this study offered an important method to reveal the relationship between the acid surface characteristics and the fracture conductivity. Besides, a digitalized and quantitative characterization method was established for the analysis of acid fracture conductivity, In addition, the results can also be a reference to acid fracturing and treatment parameters optimization.