Evaluation of downhole water sink in bottom water drive gas reservoir

Abstract

Water coning is a major problem for gas wells since it causes liquid loading in the well and obstructs gas production. There are different techniques to eliminate this problem such as using pumping unit, gas lift, plunger lift, small tubing ID, etc. One interesting technique is Downhole Water Sink (DWS) method which reduces water coning effect by producing water below the contact of hydrocarbon and water. In this study, Downhole Water Sink method is applied to a well drilled in a bottom-drive gas reservoir to enhance production performances. Sensitivity analysis is conducted by varying operating conditions in order to observe the effect of these parameters on production performance. The operating conditions studied are water withdrawal rate, gas production rate, position of perforation and its interval. The results show that DWS technique can improve recovery more than conventional technique and also reduce water production from water coning. Sensitivity analysis shows that water withdrawal rate and position of perforation in the gas zone have important effects on gas recovery factor and reduction of water production. Increasing water withdrawal rate and perforating the gas zone at the topmost results in more gas production and less water production from the gas zone. On the other hand, gas production rate and perforation interval have slight effects on gas production.