Water alternating gas (WAG) injection schemes have become an important strategy for improved oil recovery (IOR) technique around the world, and have been the focus of interest in recent years in Venezuela. This drainage strategy is mainly planned according to the major concerns in Western Venezuela oil fields: optimizing gas resources and improving oil recoveries in the region. As part of the support to identify those reservoirs that will be candidates to WAG flooding in this area of the country, an extensive review was carried out to describe the main reservoir management strategies implemented in WAG pilot, as well as large field projects in order to evaluate international field experiences, before expensive reservoir description, laboratory studies, economic evaluations and WAG pilot projects are carried out. This paper briefly describes part of this review and also shows some screening criteria for WAG floodings. Data from successfull and unsuccessfull worldwide projects have been analyzed obtaining relevant information about crude oil and reservoir properties as well as gas injection capacities, incremental oil recoveries, among others. All these data have been compiled and the results are presented graphically; the relationship between them is discussed and compared with data of some of the reservoirs proposed for WAG floods in Venezuela. It has been found that WAG projects must be initiated with injection pressures 24% greater than reservoir pressures unless the formation is deeper than 8000 ft. Additionally, incremental oil recoveries reported by those projects are higher for lower viscosity ratios and do not depends on injected solvent slug sizes. Finally, the authors discuss how this screening was useful as a first look to identify the actual reservoir and facilities of different fields located at the Maracaibo Lake (e.g. B-6-X.10 and VLE-305) and select them for closer investigation and planning WAG pilot projects or "WAG Field Laboratories". P. 161

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