Is there a pre-Cretaceous source rock in the Colombia Putumayo Basin? Clues from a study of crude oils by conventional and high resolution geochemical methods


  • M. MARTÍNEZ Ecopetrol, Exploration Vice-Presidency, Bogotá, Colombia.
  • R. MÁRQUEZ Ecopetrol, ICP, Bucaramanga, Colombia
  • G. GUTIÉRREZ Gems S.A. Bogotá, Colombia
  • L. MAYA Ecopetrol, Exploration Vice-Presidency. Bogotá, Colombia.
  • C. MORA Gems S.A. Bogotá, Colombia.
  • W. GUZMÁN Gems S.A. Bogotá, Colombia.
  • J.M. MOLDOWAN Stanford University and Biomarker Technology, Inc. Rohnert Park, California 94928, USA.



Crude Oils, Geochemical Characterization, Petroleum System, Source Rock, Oil Kitchen


A geochemical characterization of sixteen crude oil samples from the Putumayo Basin, southern Colombia, was carried out. This basin is located to the north of Ecuador’s Oriente Basin, one of the most prolific hydrocarbon basins in South America. Regardless of the fact that these two basins seem to share the same geological evolution, the volume of hydrocarbon reserves found in the Oriente Basin is five times greater than in the Putumayo Basin. This represents an exploratory opportunity to the extent that a better understanding of the petroleum system processes in the Putumayo Basin can be achieved. Newly available geochemical technology shows evidence that these crude oils originated from Late Cretaceous source rocks. The novel application of an age-related biomarker, the C25- highly branched isoprenoid, has constrained the age of the principal source of all these oils as Late Cretaceous or younger. Advanced geochemical technologies, such as compound specific isotope analyses of biomarkers (CSIA-B) and diamondoids (CSIA-D), and quantitative extended diamondoid analysis (QEDA), have confirmed, repeatedly, that the oil samples are all related to the same source with minor facies variations. The integration of these results with geological data suggests the presence of a very efficient petroleum system, characterized by an alternating sequence of soçurce and reservoir rocks. Thermal maturity of the oils from biomarker and diamondoid parameters ranges from well before the peak of hydrocarbon expulsion to the beginning of the late hydrocarbon generation phase. The aerial distribution of these maturity parameters suggests the existence of two, or possibly three, pods of active source rocks, located to the southwest and to the east of the basin, and possibly to the north. This would modify the classic hydrocarbon migration model for the Putumayo Basin, increasing the hydrocarbon potential of the basin. Given the low level of thermal maturity documented in the Cretaceous sequence that has been drilled, the possibility to evaluate the presence of a very reactive kerogen with hydrocarbon expulsion thresholds at lower temperatures is proposed.


Cooper, M.A., Addison, F.T., Alvarez, R., Coral, M., Graham, R.H., Hayward, A.B., Howe, S., Martinez, J., Naar, J., Peñas, R., Pulham, A.J., Taborda, A., 1995. Basin development and tectonic history of the Llanos Basin, Eastern Cordillera, and Middle Magdalena Valley, Colombia. American Association of Petroleum Geologists Bulletin, 79(10), 1421-1443

Córdoba, F., Buchelli, F., Moros, J., Calderón, W., Guerrero, C., Kairuz, E. C., Magoon, L., 1997. Proyecto evaluación regional Cuenca del Putumayo - Definición de los sistemas petrolíferos. Ecopetrol, Internal Report, 140pp

Dahl, J.E., Moldowan, J.M., Peters, K.E., Claypool, G.E., Rooney, M.A., Michael, G.E., Mello, M.R. and Kohnen, M.L., 1999. Diamondoid hydrocarbons as indicators of natural oil cracking. Nature, 399, 54-57

Damsté, J.S., Muyzer, G., Abbas, B., Rampen, S.W., Masse, G., Allard, W.G., Belt, S.T., Robert, J.M., Rowland, S.J., Moldowan, J.M., Barbanti, S.M., Fago, F.J., Denisevich, P., Dahl, J., Trindade, L.A.F., Schouten, S., 2004. The rise of the Rhizosolenid Diatoms. Science, 304(5670), 584-587

GEMS S.A., 2010. Colpetsys Petroleum Systems and Play Analysis of Colombian Basin (Version 2.0). Bogotá, Colombia.

Gonçalves, F.T., Mora, C.A., Córdoba, F., Kairuzb, E.C., Giraldo, B.N., 2002. Petroleum generation and migration in the Putumayo Basin, Colombia: insights from an organic geochemistry and basin modeling study in the foothills. Marine and Petroleum Geology, 19, 711-725

Hayes, J.M., Takigiku, R., Ocampo, R., Callot, H.J., Albrecht, P., 1987. Isotopic compositions and probable origins of organic molecules in the Eocene Messel shale. Nature, 329, 48-53

Hughes, W.B., 1984. Petroleum Geochemistry and Source Rock Potential of Carbonate Rock. In: Palacas, J.G., (ed.). Studies in Geology, American Association of Petroleum Geologists, 18, 71-96

Kairuz, E.C., Córdoba, F., Moros, J., Calderón, W., Buchelli, F., 2000. Sistemas petrolíferos del Putumayo, Colombia. Proceedings of the VII Simposio Bolivariano, Bogota, Colombia, 525-532

Peters, K.E., Moldowan, J.M., 1993. The Biomarker Guide: Interpreting molecular fossils in petroleum and ancient sediments. Englewood Cliffs, New Jersey, Prentice Hall, 363pp

Schoell, M., Schouten, S., Damsté, J.S., de Leeuw, J.W., Summons, R.E., 1994. A molecular organic carbon isotope record of Miocene climate changes. Science, 263, 1122-1125