Search Results (3)

Conventional development technologies for gas reservoirs have made significant advancements, particularly in well pattern optimization, enhanced recovery, and dynamic monitoring. However, multilayer thin gas reservoirs face challenges such as strong heterogeneity, thin effective thickness, poor interlayer connectivity, and difficulties in characterizing dynamic features. These factors complicate the direct application of traditional well pattern optimization methods. The gas reservoir in the western part of Block B, Right Bank of the Amu River, serves as a typical example of a multilayered thin gas reservoir. This study aims to optimize well patterns for composite layer development. A numerical simulation model is established and verified through historical fitting of production data. Using the DNN algorithm and 150 orthogonal experimental models, the optimal horizontal well pattern is determined, with a training error of 7.6% when the training set reached 120 sets. Five optimization charts for multilayer thin gas reservoirs are developed, improving the reservoir recovery factor and supporting efficient production. This work provides a theoretical foundation for the development of similar multilayer composite gas reservoirs. Full article

The extraction of shale gas from onshore and offshore shale gas reservoirs will play an important role in meeting China’s future energy needs, which will not only help alleviate the energy crisis but also contribute to climate change mitigation. As for the target shale formation enriched by thin sandstone layers in typical basins, an analytical calculation method is proposed to perform pressure analysis for multi-layer shale gas reservoirs considering the adsorption–desorption characteristics of shale layer and the interlayer cross-flow. Firstly, the changes in storage capacity and flow resistance are obtained by using the distance of investigation equation. According to the electrical analogy, the equivalent total storage capacity and flow resistance can be calculated considering the sandstone-shale crossflow. Because production from one time step to the other causes depletion of the storage capacity, the reservoir pressure in different time steps can be calculated based on the material balance equation. Numerical models have been constructed based on three typical reservoir lithology combinations (sandstone-shale, shale-sandstone-shale and sandstone-shale-sandstone) to validate the accuracy of the proposed analytical calculation method. Furthermore, three important factors (porosity, the ratio of horizontal/vertical permeability (k_h/k_v) and the layer thickness) have been selected for the sensitivity analysis to verify the stability. The comparative results indicate that the proposed analytical calculation method is suitable for pressure analysis in shale gas reservoirs containing thin sandstone layers. It will provide theoretical support for the further enhancement of the production of this type of gas reservoirs. Full article

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. Full article