Using Short Term Pressure Transients to Determine Reserves and Reservoir Character. Final Report, September 1, 1990-August 30, 1992

摘要

Static reservoir pressures are required for all gas material balance calculations. A technique has been developed for using single point, transient shut-in pressures to estimate original gas in place for pressure depleting gas reservoirs. The line generated from two or more isochronal, transient pressure buildup tests is extrapolated from the initial pressure downward to estimate original gas in place, OGIP from a p/z vs Gp plot. The technique has been shown to be universally acceptable for homogeneous gas reservoirs possessing permeabilities of greater than 0.5 md. An iterative technique has been developed for lesser permeability reservoirs. Analysis of abnormal or geopressured gas reservoir is particularly difficult because of the effects of variable formation compressibility and water influx. The solution plot and pressure plot techniques were developed. Both the solution plot and pressure plot methods permit OGIP to be determined without knowledge of water influx or formation compessibility.