The purpose of this study is to evaluate the pressure data available for the Portage Unit, which produces gas from the Grosmont Formation, and use the information to determine the pressure continuity within the unit and to determine the remaining gas-in-place based on material balance analysis. The existing dataset and prior material balance analysis indicates that the pressure in the Portage Unit was rapidly decreasing and that the OGIP reserves initially determined for the unit were significantly greater than the rapid pressure decrease for the unit would indicate. It was therefore determined that high quality pressure data was required and that a thorough evaluation and interpretation of the historical pressure data was required to determine pressure depletion trends and pressure continuity within the unit.