Novel Evaluation Methods Of Unconventional Gas Production For Ogip, And Proxy Forecast Models Available to Purchase

Currently, there is an industry assortment of production analysis methods ranging from traditional decline and typecurve matching to rate-pressure normalization techniques and detailed production history matching. Yet conventional decline analysis (despite it's many limitations) is still commonly used in gas (and oil) production analysis due to its minimal data requirements and ease of application - regardless of the development of more sophisticated methods such as those loosely defined by the term advanced decline analysis. As a result, this paper presents an automated computer method for estimating original gas-in-place and other reservoir flow parameter for unconventional (and conventional) gas reservoirs. Offshore / onshore case studies and experience presented in this paper will demonstrate that a decline and production analysis method will allow for proper identification of flow regimes, reliable evaluation of drainage area and OGIP, and the prediction of future deliverability and depletion. Case studies will also show that up-scaled and aggregate reservoir properties can provide a real measure of gas well deliverability (and therefore a simpler, time-efficient model analysis can be used). Data uncertainty, PVT error, stimulation appraisal, gas storage system (free or absorbed gas) and other factors will be discussed in the context of the case studies, and general reservoir management. Results will also show that the approach is generally accurate and robust (when used appropriately) and can provide valuable information in circumstances of poor data quality. Finally, the procedure is extremely simple and can be implemented in desktop applications or spreadsheets with minimal computational effort