Sub-Andean Basins Regional Petroleum Geochemistry of Crude Oils

The sedimentary basins along the eastern face of the Andean range commonly referred to as Sub-Andean Basins, have long been recognized for their excellent source rock quality and oil production. From western Venezuela to southern Argentina there are no fewer than fifteen (15) separate oil productive basins that lie directly east of the Andes.

Although the oils produced from these basins have widely differing characteristics, there is an obvious interrelationship throughout much of the region. To assist in the continued exploration of the region, Core Laboratories has completed a regional petroleum evaluation of selected crude oil samples from each of the major basins. The study entails the analysis of 172 oil samples distributed among twenty (20) different basins. The analytical program is extensive, and is designed to provide the necessary compositional data to accomplish detailed oil-to-oil correlations and, if needed, oil-to-source rock correlations.

The principal objectives of this study are as follows:

  • Determine the number of genetically distinct oil families distributed among the twenty basins
  • Characterize each of the oil families using both bulk property and molecular techniques including stable isotope and terpenoid biomarker analyses
  • Map the distribution of the various oil families
  • Detect and quantify the differences in thermal maturation and timing of generation as well as the effects of post-reservoir alteration on the various oil groups
  • Predict corresponding source rock depositional environments for each family based on crude oil geochemistry

To meet these objectives we have analyzed 172 crude oils from the following basins:

Maracaibo Basin, Ucayali Basin, Llanos Basin, Madre De Dios Basin, Bolivian Altiplano (seeps), Middle Magdalena Basin, Santa Cruz Basin, Upper Magdalena Basin, Noroeste Basin, Putumayo Basin, Cuyanas Basin, Oriente Basin, Neuquen Basin, Marañon Basin, Austral Basin, Barinas Basin, San Jorge Basin and Coastal Peru Basin.