Uncertainty analysis of key factors affecting fracture height based on box-behnken method

Abstract

Hydraulic fracturing technology was one of the main technologies to achieve efficient development of unconventional oil and gas resources. Longitudinal propagation of hydraulic fracture was one of the main factors affecting the reservoir stimulation. At present, there was still a lack of qualitative analysis for the problem of hydraulic fracture penetration. Based on the linear elastic fracture mechanics, the fluid-solid coupling mechanical behavior of reservoir was simulated by plane strain three-dimensional model. The longitudinal initiation and extension process of hydraulic fracture was simulated and analyzed. The effect of in-situ stress and physical parameters on fracture height was studied. At the same time, the key parameters for controlling fracture height were screened through hurricane analysis and Box-Behnken test design. Based on the response surface analysis method, a mathematical statistical model with good fit with the actual calculation results was established to predict the statistical significance of the key parameters controlling the fracture height. According to the designed fracture height, the combination of parameters corresponding to the fracture height was calculated by using the mathematical statistical model prediction. The results showed that the stress difference and elastic modulus difference between the mudstone and the conglomerate layer were the key factors to control the fracture height. The overlying mudstone layer with high in-situ stress and low elastic modulus can reduce the fracture height and effectively restrict the fracture penetration. This study had theoretical significance for understanding the mechanism of hydraulic fracturing.