Gas reservoir dynamic model and well test

The main content of this chapter, and indeed of this book as a whole, is to establish a dynamic model of the gas well and the gas reservoir mainly based on transient well test data. Three kinds of characteristic plots, i.e., pressure history plot, semilog plot of pressure, and log-log plot of pressure and its derivative, are needed in transient well test interpretation. The main method for finding the proper gas reservoir dynamic model in modern well test interpretation, which has been developed since the 1980s, is the type curve match analysis. In this analysis, a log-log plot of the measured pressure buildup data is drawn, and this plot is matched with the type curves created from the research results of percolation of fluid in the formation, recurring to the well test interpretation software to identify the type and calculate the parameters of the tested well and tested reservoir, and consequently establish the dynamic model of the gas well. The dynamic model of the gas reservoir is then established by comprehensively analyzing the dynamic model characteristics of all wells in the field. When this method is introduced in this chapter, a graphics analysis method is recommended based on the author’s experience accumulated from working in fields for many years; 16 kinds of model graphs for well test analyses commonly met in field practice and field examples of them are summed up as well.