Dynamic production characteristics and effect analysis of combined gas production well of coalbed methane and tight gas

For gas reservoirs with poor physical properties, the implementation of a single well with multi-layer combined production is an effective means to achieve efficient development. However, because of the differences in the geological conditions of the vast majority of multi-layer gas reservoirs, the dynamic characteristics of the gas wells will be complex under the multi-layer combined mining mode, and the inevitable interlayer interference in the production process will affect the development effect. In this paper, the coal seam and the dense layer are opened for production at the same time. The two kinds of different types of production are not only restricted by the heterogeneity of each layer, but also the special development mode of the coal seam. Through analyzing and summarizing the productivity equation of two kinds of production layers and the characteristics of the change of production pressure, the coupling calculation is carried out by the iterative programming of node analysis method in the wellbore, which can dynamically predict the dynamic gas production. In comparison with the dynamic gas production dynamics of combined production and the overlay production of each production layer, it is found that the amount of accumulated gas production of multiple production layers in the forecast period is only 2.56% lower than that of the single production of the multi-production layer, but the investment cost of the single well multi-layer production is far lower than that of the single production, and the stable production time of the combined production is longer, indicating that the stable production time is longer.