AN INTEGRATED APPROACH FOR REDUCING UNCERTAINTY IN THE ESTIMATION OF FORMATION WATER SATURATION AND FREE WATER LEVEL IN TIGHT GAS RESERVOIRS – CASE STUDIES

摘要

To reduce the uncertainty in the estimation of hydrocarbon in place and fluid contact in tight gas reservoirs, it is essential to integrate core data and log analysis. A newly developed JMOD (an EXCEL-based saturation-height approach) has been successfully applied to calibrate log analysis to better define petrophysical properties such as formation water saturation and free water level in tight gas reservoirs. The application of this approach has played a critical role in exploration and development decision-making processes for tight gas reservoirs. This approach is derived from capillary pressure and Leverett’s “J-Function” concepts. The approach utilizes the constants that are obtained from curve-fitting “J-Function” from measured capillary pressure data. Unlike most of the models published in the literature, this approach accommodates different forms of J-Sw regressions, which is applicable to different pore geometries and very powerful in tight gas reservoirs.