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Abstract: Petroleum Systems at the Triple Point Between the Merida Andes, the Eastern Cordillera of Colombia and the Guayana Shield: The Petroleum Geology of the Colombian-Venezuelan Border

N. Chigne, D. Loureiro, L. Rojas, H. Sanchez, C. Urbina

The sinistral Bramon-Bucaramanga shear zone, in conjunction with the southeastern vergent Falla Borde Llanero and the northwestern vergent frontal thrust of the Merida Andes, defines a complex area where tectonic transport shows crustal scale shift. Palinspastic restorations have been used as a base for the identification and reconstruction of the evolving petroleum systems, showing that several of the discontinuities within this collage served as barriers for major oil accumulations.

The main oil generating unit of the region is a 200-m-thick sequence of Cenomanian-Turonian rocks representing a variety of facies, from siliciclastic mudstones to finely laminated limestones.

Sequence stratigraphy at well-log scale combined with seismic profiles has helped to identify and map the most important reservoir-seal couples within Late Cretaceous and late Eocene-Early Miocene megasequences.

One- and two-dimensional modelling of kerogen maturation suggest a major phase of oil expulsion during Early Miocene. Loading of the source rock below Upper Miocene to Holocene thrust and/or coeval foredeep sediments has developed a petroleum system that is active today.

Oil migrated toward the local highs from active kitchens located to the west-southwest.

AAPG Search and Discovery Article #90951©1996 AAPG International Conference and Exhibition, Caracas, Venezuela