Abstract
Venezuela has been ranked as a potential oil producer country thanks to its huge reserves of conventional and unconventional oils. Conventional reservoirs with complex fluid systems, located in the North of Monagas state, where it is possible to observe thick fluid columns with significant compositional gradients (showing changes from gas condensate to non-mobile oil-Tar mat). In these types of reservoirs EOR methods such as miscible gas flooding have been successfully applied to compensate pressure decline and avoid asphaltene deposition issues.
Production of unconventional oils, the largest highly-viscous oil reservoir of La Faja Petrolifera del Orinoco (La FPO), demands great challenges. Discovered in the 1930’s, the first rigorous evaluations of this reservoir started in the 1980s [1]; those huge deposits of highly viscous oils were considered technically and economically unattractive at that time. Due to production decline of conventional oil reservoirs, efforts are being done by the Venezuelan National Oil Company and collaborators to develop EOR projects to achieve increasing oil production in unconventional (heavy and extra-heavy) reservoirs, being the most promising options thermal and chemical EOR methods.
Some authors agree that in the FPO, only 40–65% (depending on the site) of the oil-bearing formations is suitable for thermal EOR methods. Recent works have been showing the potential of chemical EOR for extra-heavy oils in La FPO [2, 3, 4, 5, 6, 7, 8, 9], mostly for mobility control and mobilization of residual oil.
This work presents a literature review of the EOR projects in Venezuela for conventional and highly viscous oils, based on both lab and field experiences, and the perspectives for applications to increase Venezuelan oil production.
SPECIFICS OF VISCOUS OIL PRODUCTION USING A DRAIN-HOLE WELL
