Downhole water drain from bottom water-drive gas reservoir into partially depleted gas reservoir

Abstract

One of the most important problems in producing gas from a water-drive gas reservoir is liquid loading. For a multi-layered system consisting of a bottom water-drive gas reservoir and a dry-gas reservoir located at a deeper location underneath, a method called “Downhole Water Drain from Bottom Water-Drive Gas Reservoir into Partially Depleted Gas Reservoir” (DWD) can help reduce water coning effect and thus increase gas recovery of the upper reservoir. At the same time, the water can be dumped into a partially-depleted gas reservoir to help increase gas recovery of the lower reservoir. The objective of this study is to determine appropriate conditions for applying DWD method in comparison with other production scenarios. ECLIPSE100 reservoir simulator was used to evaluate the performance of three production scenarios: commingled production, bottom-up production and DWD. Typical rock and fluid properties from Gulf of Thailand gas fields were used to create the reservoir model. The result from simulation showed that DWD performs better than conventional commingled method and bottom-up production methods in terms of increasing gas recovery and reducing water production. Tested with proper operating conditions among various reservoir conditions, DWD can help enhance gas recovery upto 16% from commingled and 13% from bottom-up production meanwhile DWD can help reduce water production by upto 155 MSTB from commingled and 110 MSTB from bottom-up production