Abstract: The Evolution of the Piedemonte Llanero Petroleum System, Cordillera Oriental, Colombia: (1) Structural Evolution and Play Definition

Rod Graham, Spencer Howe, John O'Leary, Andrew J. Pulham, Neil Piggott, Alwyn Vear, Edward A. Warren

The Piedemonte Llanero petroleum trend of the Cordillera Oriental in Colombia has proven to be one of the most prolific hydrocarbon provinces discovered in recent years. The Piedemonte Llanero is a fold and thrust belt of complex, multi-phase structuration and hydrocarbon generation.

Following the discovery of the Cusiana and Cupiagua fields (1991-1992) in the southern part of the trend, BP and its partners began exploration further to the northeast. Early seismic data showed the existence of two structural trends: the frontal (or basal) thrust trend, with structures similar to Cusiana; and the overthrust (or duplex) trend, with multiple imbricated structures. Improved quality seismic data defined the gross structures and allowed them to be successfully drilled (1993-1995), but did not give a constrained model for the kinematic evolution of the fold and thrust belt nor the petroleum play. This resulted in no clear predictive models for reservoir quality and hydrocarbon phase distribution in the undrilled parts of the trend.

A wide variety of geological and geochemical analytical techniques including biostratigraphy, reservoir petrology, petroleum geochemistry, thermal maturity data, basin modelling and fluid inclusion studies were undertaken. These were iteratively integrated into the seismo-structural model to develop a constrained interpretation for the evolution of the Piedemonte Llanero petroleum system.

This paper summarizes the current understanding of the structural evolution of the trend and the development of a major petroleum system. A companion paper details the reservoir petrography and petroleum geochemistry studies.

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