Gas reservoir numerical simulation is an important method to optimize the development strategy of shale gas reservoirs which has been influenced by the multi-stage fracture. The regular fracture network model was used to build a conventional numerical simulation, in which it was difficult to show the true situation of fracture propagation. However, the physical parameters not only affect the production, but also influence the stimulation effect; moreover, the quality of the fracturing effect also affects the production which causes the input and out parameters to be inaccurate. To solve this problem, the process simulation must be completed from geology to engineering to gas reservoir. The main controlling factors of production are identified with geological and engineering factors such as horizontal stage length, the volume of fracturing fluid, well spacing, production allocation, and proppant mass. Therefore, on the basis of the integrated simulation method of a hydraulic fracturing network simulation and an unstructured grid high-precision numerical simulation, this paper builds an integrated numerical simulation of a shale gas reservoir coupled with geology and engineering to optimize the development strategy with production as the target. Taking four wells of a platform as an example, the EUR (estimated ultimate recovery) has increased by 25% after the optimization of the development strategy.

Shale gas reservoirs, as representative reservoirs in the Sichuan Basin, have attracted widespread attention regarding development. Using gas reservoir numerical simulation to assist development has greatly improved the work efficiency of workers. However, traditional gas reservoir numerical simulation is widely criticized for its inability to effectively integrate with geological and engineering factors. In this study, we proposed a geological engineering integration method that considers pre-fracturing parameters. We further applied it to a typical well (N03) in a certain block of the Sichuan Basin. The reliability of the method was determined through historical fitting. Based on the N03 geological model, the optimization range of fracturing construction parameters in adjacent areas was determined with the goal of maximizing EUR. Recommended values for widely distributed construction parameter combinations of Class II reservoirs were provided through orthogonal analysis. The influence order of fracturing construction parameters is (1) sand addition strength, (2) cluster spacing, (3) construction displacement, (4) fracture fluid strength, and (5) horizontal segment length. Finally, we compared the simulated data with the actual case. The results showed that an integrated numerical simulation method including geological and engineering factors can comprehensively and accurately assist in reservoir development.

Shale gas development in China is dominated by high-pressure gas reservoirs occurring in deep horizons in Sichuan Basin and its peripheral areas. With the progress of exploration and development technologies, medium-shallow normal-pressure shale gas represented by Anchang Syncline in Guizhou has also realized commercial operation. To address the problems of overall low production and high gas breakthrough flowback ratio of medium-shallow normal-pressure shale gas, this paper systematically analyzes its development performance laws based on the complex tectonic setting and the reservoir characteristics of “four lows and one high” of the Anchang Syncline. A series of key technologies were developed, including the static–dynamic iterative identification technology for faults and micro-amplitude structures in complex tectonic areas, the coupled iterative fine modeling technology of geology-development dual chain, the iterative optimization technology of fractures and simulation parameters, as well as low-cost drilling-completion and drainage-production process technology. The application of the above technical suite achieved commercial development of normal-pressure shale gas. By the end of 2024, 66 wells had produced 6.5 × 10⁸ m³ cumulatively, and the well Estimated Ultimate Recovery (EUR) is 2000–4000 × 10⁴ m³. It was clarified that geological conditions constitute the intrinsic basis of gas well production capacity, and engineering factors such as horizontal section length, well type selection, fracturing matching degree, and drainage-production timing are the key to production enhancement. The established development technical system and practical experience for normal-pressure shale gas provide an important reference for the efficient development of analogous gas reservoirs.