Rate-time decline analysis for natural gas wells with significant rock compressibility effects

State-of-the-art analysis of production performance of gas wells relies on material balance concepts combined with pseudo-pressure and pseudo-time for rate-time decline analysis and reserve estimations. Customarily, rock compressibility and reservoir pore volume change are either neglected or accounted for by replacing gas compressibility with total compressibility values. In this work, we extend the applicability of a rescaled exponential and density-based decline analysis approach (Ayala and Ye, 2012 and Ayala and Ye, 2013) for the decline analysis of gas systems experiencing significant rock compressibility effects. We formally derive the density-based analytical technique that rigorously captures formation compressibility effects during for the analysis of gas well production data during boundary-dominated-flow (BDF). This formulation enables calculation of correct prediction of well performance with depletion) by incorporating formation compressibility and the change of reservoir pore volume effects, which proves crucially important for high-pressure and/or large-formation-compressibility gas reservoir systems.