Study on the Influencing Factors of Hydraulic Fracture Propagation in Deep Unconventional Gas Reservoirs

Abstract

To fully understand the factors influencing hydraulic fracture propagation in deep unconventional gas reservoirs, this study takes a block in China as an example. Firstly, a comprehensive geological mechanics model of the reservoir is constructed. From the perspectives of discrete natural fracture modeling, hydraulic fracture propagation analysis, and hydraulic fracturing numerical modeling, an analysis model of the influencing factors of hydraulic fracture propagation in the reservoir is established. This model is then used to conduct an analysis of the influencing factors, laying the foundation for optimizing fracturing design and improving fracturing effectiveness. The study shows that among factors such as cluster spacing, fluid intensity, natural fracture line density, and horizontal stress difference, cluster spacing has the greatest impact on hydraulic fracture propagation in the reservoir, followed by fluid intensity, while horizontal stress difference has the least impact. Under the condition of gradually increasing cluster spacing, the modified reservoir volume will initially increase and then decrease. As fluid intensity gradually increases, the modified reservoir volume will also increase, but due to economic constraints, fluid intensity should not be excessively high. When the natural fracture line density is low, the rate of increase in modified reservoir volume is relatively fast as it increases. However, when the natural fracture line density is high, the rate of increase in modified reservoir volume slows down as it continues to increase. As the horizontal principal stress difference gradually increases, the modified reservoir volume will gradually decrease.