Cesar Mora¹, Felix T.T. Gonçalves¹, Antonio Rangel¹

(1) Ecopetrol-ICP, Bucaramanga, Colombia

ABSTRACT: Complementary Plays in the Llanos Orientales Basin (Colombia) Based on the Geochemical Characterization and Mapping of Oil Families

The Llanos Basin has the largest oil reserves in Colombia (3,415 MBOE), holding three of the four biggest fields of the country: Caño Limon (1034 MBOE), Cusiana (900 MBOE) and Cupiagua (700 MBOE). These accumulations are related to two major structural plays: fold belt in Eastern Cordillera foothills and subtle anticlines in the foreland. The geochemical characterization of 68 oil samples allows the definition of four different families associated to marine carbonate, marine siliciclastic and deltaic source rocks. There are clear evidences of mixing of oils from different source rocks, especially in the central-southern portion of the basin. Current physical properties of the oils were controlled by the origin (source rock characteristics), biodegradation vs. migration histories, and degree of oil mixing. During the last decade, the application of the petroleum system and complementary play concepts (Magoon, 1995) has provided a new rationale to approach petroleum research and to evaluate exploration risk. The mapping of geographical distribution of the oils related to each family allowed the identification of complementary plays in three distinct areas: (1) Llanos foothils, between the Cupiagua-Cusiana and the Arauca fields; (2) Central-northern Llanos Basin, between the Caño Limón field and the Cororora-1 well; and (3) the Eastern border of the Llanos foreland. Such approach provides basis for a better assessment of the remaining potential and exploration risk of finding hydrocarbons associated with each petroleum system of the Llanos Basin.

AAPG Search and Discovery Article #90906©2001 AAPG Annual Convention, Denver, Colorado