Production data analysis of gas reservoirs with edge aquifer drive: A semi-analytical approach

Abstract

Production data analysis is proved to be an efficient reservoir engineering tool that can be utilized to estimate some important reservoir parameters including fluid in place and, average reservoir pressure. Among the available production data methods, flowing material balance is more popular. In spite of the development of this method for volumetric gas and, oil reservoirs over the past years, non-volumetric effect doesn't feature the equations. In this paper, modified flowing material balance equations are proposed for production data analysis of gas reservoirs subjected to finite-extended edge aquifer. The validity of the presented equations is performed using analytical solutions. For the development of analytical solutions, special simplifying assumptions are considered. To evaluate these assumptions, a comparison is performed using a commercial numerical reservoir simulator for some models with different rock and, fluid properties. Moreover, the introduced flowing material balance equation is combined with material balance equation in order to find a simple equation to calculate average reservoir pressure. Detailed steps are presented to determine gas in place of and, average reservoir pressure of this kind of reservoirs. Furthermore, for a better match between analytical and numerical outputs of gas flow rates, a correction coefficient is recommended which depends on the strength of aquifer.