Study on the Mechanism of Effective Sweep Range Influence in High-Angle Fracture Foam Flooding

High angle fractures are widely present in carbonate rocks, shale oil and gas reservoirs, and sedimentary reservoirs near fault zones, and are important storage spaces for oil and gas resources. The low longitudinal sweep efficiency caused by gas channeling in fractures and edge and bottom water can be effectively solved by profile control and flooding using the characteristics of foam fluid such as moderate density and controllable mobility. However, the impact of foam stability on its effective sweep range is still unclear. Based on the observation of experimental phenomena, the research firstly analyzes the front shape of foam in the plate crack (simplified model of high angle crack), forming the basic understanding of the distribution law of foam in the high angle crack, that is, the calculation model; Further, by analyzing the stability of foam and fitting the change curve, calculate the effective swept volume of foam in the fracture; Finally, based on the finite element method, the shape control parameters of foam distribution and migration front are calculated, and the chart of the relationship between the effective sweep radius of foam and the fracture size is drawn. The research results show that the stability of foam in high angle fractures is the key factor of its effective swept volume. Taking the half-life of foam as the critical time of foam failure, the maximum effective swept volume of TH-2 polymer foam in high angle fractures is 949.30 m3, and the change of fracture opening has greater influence on the effective swept radius of foam than the fracture depth. The research forms the understanding of effective swept volume under the influence of foam stability, and provides a reference for the calculation of effective swept radius of foam under the condition of different scale fractures in the field.