Steady Periodic Gas Flow Around a Well of a CAES Plant

The design of a Compressed Air Energy Storage (CAES) plant requires knowledge of the pressure and temperature variations within the reservoir, for expected sets of plant operation. In the current work, a closed form approximate analytical solution for the pressure variations, in porous media reservoirs, was derived for conditions of steady periodic isothermal radial gas flow. Two different expressions for the pressure variation were obtained, one as an infinite series and the other as an integral, where the latter is the computationally preferred solution. In order to evaluate the model accuracy, a finite difference numerical solution of the full non-linear problem was developed. The accuracy of the analytical solution was confirmed through, both, error analysis and comparison against the numerical calculations. The analytical solution can be used to calculate the well pressure variations and the radius of the active region around the well. Examples of calculations are provided, and a parametric study is presented to demonstrate the sensitivity of the well pressure to pertinent parameters. The model could eventually yield improved CAES plant designs.