Optimization of the injection-production process of underground gas storage in depleted gas reservoir

In this work, a framework is proposed for optimizing the injection-production process of underground gas storage in depleted gas reservoir. The optimization problem is formulized as a minimization problem with multiple constraints. The objective function is defined with respect to the pressure change. And, the constraints are introduced with respect to the injection (or production) amount, injection (or production) rate, and reservoir pressure. Spatial allocation coefficients and temporal allocation coefficients are introduced as the control variables. Ensemble-based minimization method is adopted for updating the control variables. The Brugge model is modified as a depleted gas reservoir for testing the proposed method. Both one-month and multi-month injection (or production) optimizations are investigated. Through minimizing the defined objective function, the proposed method can provide the optimized injection (or production) plan for all of the wells, and can identify the wells that are not recommended for use. Based on the reservoir pressure constraints, the feasibility of different injection (or production) target within a given time period for an underground gas storage site can be evaluated. The proposed method can be helpful for the safe and intelligent operation of underground gas storage.