Proppants are one of the key materials for hydraulic fracturing, whose main role is to support fractures and create a channel through which oil and gas can flow. The nature of proppants is the most talked about feature besides their cost, for example, their sphericity, turbidity, particle size, or strength. The porosity, permeability, and fracture conductivity of proppants in fractures are also the main indicators to measure the performance of them. These indicators are usually obtained through physical experiments. However, experimental results often differ depending on the experimental scheme. Different stacking methods of proppant particles lead to this phenomenon. The nature of proppant particles in fractures varies with the way they accumulate. This paper will start with the microscopic arrangement of proppant particles. Considering the randomness and certainty of three-dimensional particle stacking and arrangement, the Monte Carlo stochastic method and an optimization model were used to conduct three-dimensional computer simulation of proppant particles. This lays an important foundation for revealing the randomness and regularity of the micro arrangement of proppant particles.

Hydraulic fracturing is an important measure and main method for increasing production of coal reservoir. As one of the key materials of hydraulic fracturing, fracturing fluid directly determines the production of wells and greatly affects economic benefits. According to the requirement of fracturing fluid for large inclined coal seam, the low viscosity active water fracturing fluid was used in the early stage of fracturing, and the high viscosity clean fracturing fluid was used in fracturing and sand adding, thus forming a complex fracturing fluid system. After field construction application, the entering fluid and the operating pressure of the complex fracturing fluid system are lower than those of the active water fracturing fluid well, that shows that the compound fracturing fluid has many advantages, such as high fracture efficiency, strong sand carrying performance, small friction coefficient and high success rate. The desorption pressure, average gas production, bottom hole flow pressure and the highest gas yield of wells operated with compound fracturing fluid are all higher than those of wells operated with active water fracturing fluid, which shows good potential for high yield.

Hydraulic fracturing is an important measure and main method to increase storage, production, and effective development of coalbed gas wells. And correctly understanding the morphology and geometric dimensions of fractures is the key to hydraulic fracturing stimulation. In order to understand the formation, analyze and evaluate the quality of fracturing construction, a three-dimensional propagation model of vertical fracture is established by using fluid mechanics and linear elastic fracture mechanics. The model considers the multi-layered and heterogeneous characteristics of the coal seam, that is, multi-layered coal seam thickness, in-situ stress, and rock mechanics parameters such as Poisson's ratio, elastic modulus and fracture toughness. The model can simulate arbitrary multilayered stress distribution patterns and the propagation of the fracture before and after the layer. Research and develop three-dimensional extension simulation software for vertical cracks of CBM wells. Through the calculation of the example, the calculated value of the established three-dimensional fracture propagation model coincides with the fracture parameter interpretation result, which verifies the practicability and reliability of the model.