Simplified approach for predicting gas well performance

This paper presents the development and application of a simple, yet reasonably accurate, method for predicting gas well performance. The proposed approach is based on predicting average reservoir pressure at different time intervals from stabilized surface production-history data using an iterative mode of calculations. The calculated (P̅r/z) values are then plotted versus cumulative gas production (Gp) and the straight line which best fits the data points can then be reasonably projected into any future stage of depletion to predict the remaining reserves. The present technique is suitable whenever the loss of cash flow due to shut-in production and/or the use of special sensing down-hole equipment become prohibitive, particularly when H2S and CO2 are present in the produced gas mixture. Dry gas wells, wet gas wells, and condensate gas wells can be treated with the proposed technique. All calculations are performed with Excel spread sheet solver and flow diagrams of these calculations are included in this paper.