Modeling of Proppant Embedment: Elastic Deformation and Creep Deformation

Abstract Unconventional reservoir has become the hotspot of development in petroleum industry. In shale reservoir, some fracture is only propped by a monolayer 100mesh proppant. Fracture width is very small and under the condition of low rock hardness and high effective closure stress, the fracture will heal after a period of time, especially after the rock has been exposed to the fracturing fluids, causing weakening of the rock frame. In these reservoirs, proppant embedment becomes more serious. This paper purposes two embedment mechanisms, elastic deformation and creep deformation, and develops the corresponding models by combining simplified physical processes with elastic theory. Then with time integral, pressure dependent embedment depth is achieved. This paper provides a more reasonable method for calculating embedment. For fracturing engineer, it will give them a way to know how worse the matter will be. Finally, the model could couple with fracture propagation model and production prediction model to get a better result. According to the results of analysis in the paper, in shale formation, proppant will cause creep deformation of rock, which will decrease fracture width with time. Optimization of fracturing fluid and treatment procedure are required to reduce the influence of creep deformation. Poisson's Ratio do have an effect on proppant embedment but very little. The mechanisms described in the paper provide a new understanding about embedment. It provides us a tool to determine how much the degree will be.