Global Field, Pilot and Laboratory Experience of FOR-WAG Flooding- Will it Make A Difference?

摘要

Primary and secondary drive oil production mechanisms are coming short in meeting the ever increasing global oil demand. Currently, many tertiary recovery-EOR projects are in the design or implementation stage in many parts of the world to help meeting the expected extra oil demand. The majority of these projects involve some kind of gas (CO2) injection. If injected below Minimum Miscibility Pressure, gas injection, however, suffers the problem of unfavorable mobility ratio which often reduces the chances of higher oil recovery in addition to adverse economic results due to gas recycling. To help match the technical results of these projects with their economic viability under the current oil prices, the industry should learn from the lessons of the available global experience of water alternating gas flooding to safeguard against un-optimized gas (CO2) injection projects. This should help to avoid unnecessary losses in time and money and to make the best incremental oil recovery possible. The results of large number of WAG flooding projects have been reported in the literature. Areas of application include the USA, North Sea, South East Asia, and Middle East. In this study, most if not all of the published literature on WAG process is reviewed and evaluated. Results related to the issues of screening studies, laboratory and modeling studies, and the evaluation of pilot and field applications are discussed and presented. Effort is made to show the pros and cons of the WAG process as opposed to only gas (CO2) injection. All these issues are presented in a comparative mode between the different global projects, resulting in best practices for studying WAG Flooding in the lab and via modeling, for pilot and field applications. Finally this paper makes recommendations for increasing oil recovery with less time and effort in the most economical fashion