Rigorous gas field production data analysis

With the advent of permanent downhole gauges and automated flowing tubing head pressure measurements, today’s engineers have a veritable plethora of production data on which to characterise gas reservoirs and estimate their ultimate recovery. As consultants, the authors see datasets that have not always been examined to their fullest potential. More often than not this is due to a singular approach to analysis, rather than application of a range of analyses. This paper discusses how combining traditional and more advanced production data analysis techniques has provided insight into fields ranging from tight gas reservoirs to conventional reservoirs under active waterdrive. Such insight is not obtained from brute force application of one size fits all techniques but understanding and using the appropriate combination of techniques that are likely to illuminate the underlying physics of the reservoir at hand. The authors have seen examples where basic data analysis has identified resource ranges outside the range estimated from sensitivity studies with detailed and sophisticated but effectively singular models.