IMPACT OF LEAKAGE MODEL SELECTION ON HYDRAULIC FRACTURING DATA INTERPRETATION

The paper examines the issues of modeling a hydraulic fracturing crack, which arises when analyzing the leakage of hydraulic fracturing fluid into the formation. Fluid leakage into the formation are subdivided into normal (not dependent on pressure) and pressure-dependent. Pressure-dependent leakages occur during hydraulic fracturing in fields with low filtration properties. The importance of accounting for such leakage is demonstrated by a specific example. It is shown that the choice of a pressure-independent leakage model affects the required calculated volume of injected fluid. In case of an error in choosing a model, this, in turn, leads to the effect of proppant bridging and, as a consequence, failure to achieve the calculated fracture geometry. The purpose of the work is to study the process of fluid leakage during hydraulic fracturing and to develop an approach to correctly accounting for the type of leakage encountered in the process of preparing for hydraulic fracturing. A function consisting of a pressure-dependent leakage multiplier is presented, which allows one to describe the behavior of pressure during liquid injection and after the injection is stopped. The paper proposes an approach associated with detecting a pressure-dependent fluid leakage, calibrating the calculated pressure of a test injection in the presence of a pressure-dependent leakage using the leakage multiplier function, and taking into account the resulting function at the hydraulic fracturing design stage. The proposed approach makes it possible to more correctly describe the behavior of pressure in the presence of a leakage that depends on it, which helps to improve the quality of hydraulic fracture modeling. Based on the analysis of available data, the ratio of normal leakages and pressure-dependent leakages encountered was determined. It has been shown that the dependence of leakage on pressure is regularly encountered in field conditions.