Abstract
This paper summarizes the results of several successful WAG projects presented in many Improved Oil Recovery (IOR) Symposiums, indicating the main technical and operational issues considered in the development and implementation of such projects, and the management strategy for monitoring the process (Refs. 1,2,3,4). The results from these field applications will serve as useful guides and examples for improving reserves from many of our mature fields, and would lead to rethinking our strategy of reservoir development and new technology application for significant reserves enhancement in Venezuela. The paper focus on the selection of the technical aspects that must be consider in the implementation and management of the Water Alternating Gas (WAG) Injection process, providing an useable reference for the front line geoscientists, reservoir engineers, production operation engineers and technical managers who wish to obtain a technical and operational overview of the process as applied in the petroleum industry.
Managing W AG injection projects requires making decisions regarding to the WAG ratio, half-cycle-slug size, and ultimate solvent slug size for each WAG injector in the field. The impact of these decisions affects the capital cost of solvent purchase, water and gas plant loads, fluid handling and lifting operation costs, and ultimate incremental oil recovery. Simulation models provide a tool for examining strategies for these decisions. However, it must be able to address operational impacts such as lift method and problems, injecting plugging, workovers and facilities operations. Project monitoring incorporating actual performance data into the reservoir models provides an excellent diagnostic tool for decision making. The technical considerations for managing WAG projects presented in this paper can be used as a methodology for monitoring projects performance at pattern and full field level, increasing understanding of the process performance, and improving decision making.
