With the deepening of exploration and development of tight sandstone gas reservoirs, the remaining recoverable reservoirs gradually become thinner with the vertical stratigraphic structure. The geomechanical properties become complex, and development based on conventional hydraulic fracturing methods often leads to serious problems, such as difficult control of fracture height, penetrating interlayers, too short fracture length, and inadequate proppant filling. In view of the above problems, we conducted a numerical investigation on a hydraulic fracturing scheme in a multi-layered and thin tight sandstone gas reservoir. According to the dataset from wells in a real gas reservoir in China’s Ordos Basin, the relevant geomechanical characteristics of the gas layers, together with the interlayers in the main production interval, were obtained, based on which, a fine numerical model was developed. By using the PL3D fracture propagation algorithm, a 3D hydraulic fracture propagation model was produced, and then using microseismic monitoring and production data matching, a high-precision hydraulic fracture model of the multi-layered and thin tight sandstone gas reservoir was obtained. On this basis, the influence of different geomechanical parameters and fracturing operational parameters on hydraulic fracture propagation was analyzed. Finally, an optimized hydraulic fracturing scheme that fitted the characteristics of the multi-layered and thin tight sandstone gas reservoir was proposed. Using a typical reservoir example, the optimized scheme enabled control of the fracture height in thin layers and the creation of long fractures with better proppant filling, so that the productivity of the fracture was significantly improved.

Hydraulic fracturing is a necessary measurement to realize the commercial exploitation of oil and gas, but its application in multilayered thin tight sandstone gas reservoirs is still not perfect, which usually have thin gas layers mixed with complex intervals, and shows a dramatic variation in geological and geomechanical properties in the vertical direction. When conventional hydraulic fracturing methods are applied to this kind of reservoir, it is hard to get proper fracture propagation, especially for fracture height control. Facing this situation, this paper proposes a numerical study of the hydraulic fracturing mechanism and analyzes its influencing factors in the multilayered thin tight sandstone gas reservoir. Relying on a real reservoir in the Ordos Basin in China, relevant geological and geomechanical parameters of major gas layers and interlayers are obtained. According to these parameters, the hydraulic fracturing simulation in the multilayered thin tight gas reservoir model is carried out, based on which, the sensitivity analysis of different geological and fracturing parameters which affect the fracture propagation is performed. Furthermore, a real low-production well after fracturing in this kind of reservoir is selected as an example, and based on the analysis, an optimized fracturing scheme is proposed to adapt to the characteristics of the reservoir. According to the comparison of fracturing and production simulations, the optimized fracturing scheme can prevent hydraulic fractures from breaking through thin interlayers, control the fracture height, and prevent fractures from communicating strata with a high water-bearing layer. At the same time, with the same amount of proppant and fracturing fluid, longer fracture length and better fracture conductivity are created, so that the productivity of the optimized fracture has been greatly improved.