Sistemas Petroleros De La Cuenca Oriente. Ecuador

Ecuador Oriente Basin owns the main country oil accumulation and production (30 x l0~ bo original in place). The most important petroleum system of the basin is Napo-Napo (I). It is integrated of Cretaceous to Tertiary marine and continental deposits and the<br>hydrocarbon generation started during the Neogene, favored by the Andean tectonics. Main source rock is the Cretaceous marine Napo Group, kerogen type I and II shales and limestones with 2 to 6% TOO. Oil carriers and main reservoirs are Cretaceous sandstones, affected by low to moderate burial, with excellent preserved petrophysical conditions. Traps are mainly structural and combined (structural-stratigraphic). Recent geochemical studies proved that vitrinite reflectance values could very often be<br>suppressed, showing lower maturity values that those inferred by biomarkers on source rock and oil. In this context, it is recommended to use the kerogen transformation rate as a more reliable maturity parameter. Kitchen identification using basin modeling as a routine should be made in order to better evaluate the petroleum system. The high variability of API density in the Oriente Basin can be explained as a consequence of biodegradation, occurring during various migration stages, superimposed to the maturity of generated hydrocarbons and the high variability of organic fades related to the sedimentary depositional environment of the Napo Group.