As conventional hydrocarbon supplies tighten, world energy consumption rises and new technology emerges, unconventional sources of hydrocarbons are increasingly contributing more to the world energy basket. As a consequence, the upstream petroleum industry has more sharply focused its efforts in studying unconventional reservoirs during the last decade, especially those with extra-heavy oil. Most of the reservoirs with extra-heavy oil accumulations are too geographically widespread to be commercially attractive. One exception is the Orinoco oil belt region, located in eastern Venezuela, which contains enormous deposits of extra-heavy oil.

Both international and national oil companies have formed Empresas Mixtas (joint ventures) with Petróleos de Venezuela (PDVSA) to explore and produce lease blocks in the Orinoco region during the last few years. The experience of these joint ventures shows that the extra-heavy oil can be economically extracted with cold production at higher production rates than those observed in other regions with hydrocarbons of similar characteristics (Dusseault, M. B.) The total developed acreage in production by JVs today represents only fraction of the potentially commercial area of the Orinoco Oil Belt, leaving a significant remaining undeveloped region.

The Orinoco oil belt is divided into four areas: Ayacucho, Boyacá, Carabobo and Junín. The authors conducted a detailed evaluation of PDVSA's Junín area reservoir data and revised technical interpretations and reached some key conclusions in the study. This paper summarizes reservoir characterization rationale and procedures and significant study findings, including those addressing assessed volumes of original oil in place and recovery factors.

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