Patterns in the formation and parameterization of the fracture system emerging during a multi-stage hydraulic fracturing in tight reservoirs under different modeling approaches

A system of artificially created fractures formed during multi-stage hydraulic fracturing in a low-permeable gas-saturated reservoirs has been investigated in this study. The task addressed is to parameterize the object under consideration given limited input geomechanical information. The results of hydraulic fractures modeling have been obtained, as well as their geometric and filtration parameters, by using analytical and explicit numerical methods. Interpretation of the findings revealed the limitations in analytical methods when considering the geomechanical properties of rocks; specifically, their reservoir and geomechanical heterogeneities and stimulation design. The consequence is the greatly increased uncertainty in production forecasting because fractures are represented by average values of key parameters (L = 120–330 m, w = 2.4–7.8 mm) for determining well productivity. The explicit method demonstrated higher flexibility and adaptability depending on the available input data. The average results, which were obtained by applying both methods, showed similarity between key parameters (L = 199–339 m, w = 7–10 mm, Cf = 774–1098 mD*m), which confirms these methods' validity. However, the ability of the explicit modeling approach to provide a detailed description of key fracture parameters, including 3D geometry, variation of fracture width (w = 3–11 mm), and proppant saturation over the fractured area (Cp = 75%), gives a higher priority to this method during research. The use of an explicit method, in contrast to the analytical one, makes it possible to determine the asymmetry of the fracture flanks, relative to the direction of the minimum horizontal stress, the change in thickness and permeability along the fracture, the distribution and concentration of proppant. All this leads to an uncertainty ranges reduction in the production forecast from horizontal wells with multi-stage hydraulic fracturing, during the development of shale reservoirs. This is the next step for further use of the results.