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Evaluation of Petroleum Systems in the Carúpano Basin, Offshore Venezuela, through 3-D Basin Modeling

Pérez, Adriana C.*1; Berrio, Irenio 1
(1) E&P, PDVSA-Intevep, Los Teques, Venezuela.

The Tertiary Carúpano Basin is located offshore of northeastern Venezuela. The presence of hydrocarbons in this area had been confirmed by production of condensates and gas. The molecular and isotopic composition of gases from some wells, suggest the presence of at least two petroleum systems, thermogenic and biogenic. The aim of this study was to identify and evaluate the thermogenic petroleum systems in the area by using 3D basin modeling; in order to help reduce uncertainty in exploration.

The methodology was based on 1) 3D geometric model building 2) gridding, 3) assignment of the properties of the elements of the petroleum system 4) backward and forward modeling and 5) semi-quantitative evaluation of hydrocarbons generated in the Carúpano Basin. This methodology permitted to get a 3D block with the main characteristics of the Carúpano Basin. Semi-quantitative evaluation of thermogenic hydrocarbons generated in the Basin allowed to get values of generation-accumulation efficiency (GAE) of the petroleum systems identified in the basin. The results of simulations suggest that from "all the potential source rocks" evaluated in the area, the Eocene and Oligocene succession were the most suitable for generation and expulsion of hydrocarbons. Early Miocene deposits reached the maturity level for generating but they have not expelled enough hydrocarbons for commercial accumulations or probably the traps had not developed yet.

During early Miocene, when expulsion of hydrocarbons began, the main reservoir (late Miocene rocks) started its sedimentation. This reflects the lack of synchronization between the events of generation, migration and accumulation of hydrocarbons from lower Miocene rocks. However, hydrocarbons from Eocene and Oligocene source rocks could be trapped in the sandy facies of upper Miocene and lower Pliocene deposits. Additionally, the Eocene succession retained oil in the upper sands, in traps associated with anticlines. The values of GAEs obtained for the petroleum systems described (Eocene-Eocene (?), GAE: 0,015 % and Oligocene-late Miocene (?), GAE: 4,12 x 10-4 %) are considerably lower and they can be classified as inefficient. However, the results obtained suggest that this area has a high potential for hydrocarbon exploration, not only in the intervals already drilled but in intervals as deep as Eocene, which should be studied in more detail in order increase opportunities for exploration in the area.


AAPG Search and Discovery Article #90142 © 2012 AAPG Annual Convention and Exhibition, April 22-25, 2012, Long Beach, California