Semi-Analytical Model of A Multi-Well System with well Interference During Underground Gas Storage

Abstract Underground gas storage (UGS) is an important source for regulating natural gas supply. The large injection or production rate causes well interference in UGS to be particularly serious. Current well testing workflows for UGS assume a single well. This paper proposes a novel multi-well solution and related analysis method to analyze targeted well performance in a multi-well system. On the basis of the constant rate solution, Laplace transforms, and the superposition principle, we obtained multi-well solutions for transient flow. A systematic validation of the proposed method was conducted using a commercial numerical simulator for cases of gas storage and recovery process in UGS. Results show that the long-term gas injection and production process in UGS further exacerbates the influence of formation heterogeneity and interference. As adjacent wells are producing, the pressure derivative finally exhibits pseudo radial flow of the multi-well system under the influence of well interference. The horizontal derivative value is related to the dimensionless production rate of the target well, adjacent wells, mobility ratio, and the traditional 0.5 value. When adjacent wells are injecting, the last flow that appears in the derivative curve shows a drop-off feature. Our methodology applied to analysis of UGS performance in the Hutubi gas reservoir in China provides better estimates of the in-place natural gas resource and formation properties in this multi-well system. The methodology also provides a consistent and direct analysis of reservoir performance when "well interference "effects are observed.