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Smart Water-Alternating-Gas EOR Using Downhole Control Valve (WAG-CV): Concepts, Tools and Numerical Optimization
- Publisher: European Association of Geoscientists & Engineers
- Source: Conference Proceedings, 77th EAGE Conference and Exhibition 2015, Jun 2015, Volume 2015, p.1 - 5
Abstract
Water-Alternating-Gas (WAG) injection is an accepted EOR process commonly applied to oil reservoirs to improve oil recovery beyond conventional water or gas injection. The objective of the WAG process is to reduce residual oil saturation after conventional water or gas injection and control early water or gas breakthrough to the producers. Depending upon reservoir conditions, e.g. fluid, rock types, viscosity and rock wettability; water is injected into the reservoir for 2–6 months followed by a slug of gas, and the cycle is repeated.
For horizontal wells with lateral sections longer than 3,000 feet, controlling the injection point is very difficult due to the Toe-Heel Effect, which refers to how most of the injection water may go into the first 1,000 feet or so of the well, leaving the rest of the lateral section with limited to no injection.
In this work, the authors propose continuous injection of water and gas, injecting water through production casing and gas through tubing while selecting the optimum injection points for water and gas individually along the lateral section. This injection selectivity is achieved by using several Interval Control Valves (ICV’s) and a new mechanical well configuration to enable this type of continuous injection.