Chapter 10. Original and Remaining Gas in Place

The definition of volumetric original gas in place (OGIP) at well-to-field scale is an outcome of the Hugoton cellular model and one of the main objectives of HAMP. OGIP is both a tool for reservoir management and for evaluating whether the static model accurately represents the reservoir system. Comparing volumetric OGIP with remaining gas in place (RGIP) at well, multi-well, to more regional scale in 2-D will assist operators in identifying areas where there could be potential for modification of current practices to exploit additional reserves. The same comparisons in 3-D, taking into account producing zones and their respective properties, would add to the usefulness of the model. OGIP/RGIP comparison should also help identify areas where evaluation of current model parameters should be scrutinized, and, potentially, changes made. The current model OGIP appears to accurately represent the reservoir in the central portion of the field, accounting for the majority of the gas produced, but in areas around the perimeter some adjustments to certain model parameters are likely to be needed (e.g., free water level).