A material balance solution to estimate the initial gas in-place and predict the driving mechanism for abnormally high-pressured gas reservoirs

This paper presents a material balance solution for estimating the initial gas in-place and predicting the prevailing production mechanism for abnormally high-pressured gas reservoirs. The material balance solution incorporates water influx from associated aquifer, water influx from shale, formation expansion, connate water expansion and formation of condensate. Application of the proposed solution to four case histories of abnormally high-pressured gas reservoirs, shows that this solution would successfully estimate the IGIP. In comparison with the available methods, the proposed solution has the advantages of requiring no prior assumptions about the formation compressibility, aquifer size, or volume of adjacent shales for estimating the initial gas in-place.