Abstract

AVENDANO-SANCHEZ, Gladys Marcela; GARCIA-GONZALEZ, Mario; CRUZ-GUEVARA, Luis Enrique  and  CRUZ-CEBALLOS, Luis Felipe. Thermal evolution of Los Cuervos formation in the southern area of the Cesar sub-basin (Colombia), based on geochemical and petrophysical data. Earth Sci. Res. J. [online]. 2021, vol.25, n.2, pp.179-192.  Epub Oct 15, 2021. ISSN 1794-6190.  https://doi.org/10.15446/esrj.v25n2.86025.

The tectonic complexity that occurred during the Cenozoic at the Cesar-Ranchería Basin (Colombia) has generated changes in the evolution of its petroleum system. Proof of this is the lack of stratigraphic records in the Cesar sub-basin during both the early Eocene and in the late Eocene-early Miocene interval. In this study, authors analyzed information already published regarding the sub-basin and new geochemical data obtained from Rock-Eval pyrolysis analyses and vitrinite reflectance (Ro%). The core samples used are from the ANH-La Loma-2 and ANH-CR-Los Cerezos-1X wells. Based on this information, Los Cuervos Formation was classified as a source rock for its geochemical characteristics. Additionally, the geochemical and petrophysical results indicate continuous deposition of sediments from the Paleocene to the late Eocene. These results were obtained using samples from two wells (Calenturitas and La Jagua) at Los Cuervos Formation and the paleo-geothermometer data of Paleocene formations. Based on density and compaction conditions, it is clear that it corresponds to a sequence of quartz sandstones. Therefore, it is expected the Eocene Sedimentites unit has reached a thickness between 2.5 to 3.5 km. According to recent thermo-chronological studies, this unit began to be eroded from the late Eocene to the early Miocene. The evidence obtained helped improve the knowledge in the thermal evolution model of the petroleum system, establish the time when the organic transformation ratios (TR) occurred, and estimate the current state of the Cretaceous source rocks of the Cesar sub-basin.

Keywords : Cesar-Rancheria Basin; Cesar sub-basin; Los Cuervos Formation; Source Rock; Geochemical Modelling; Porosity-Depth Relation.

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