Tectonic and Hydrocarbon Comparisons Between Two Colombian Foreland Basins: Llanos and Putumayo

Authors: Paul Mann (presenter), University of Houston; Luis Fernando Pachon-Parra, University of Houston, GEMS, Ltd. (Colombia); Nestor Cardozo, University of Stavanger

The Putumayo foreland basin (PFB) is a hydrocarbon-bearing basin located in southernmost Colombia and forms a 250-km long segment of the 7000-km-long corridor of Late Cretaceous-Cenozoic foreland basins formed by the eastward thrusting of the Andean mountain chain over Precambrian rocks of the South American craton. We summarize the tectonic and hydrocarbon characteristics of the Putumayo foreland basin with its larger and deeper cousin to the north, the Llanos foreland basin.

For the Putumayo, we use 4000 km of 2D seismic data tied to 28 exploratory wells to describe the basin-wide structure and stratigraphy of this promising hydrocarbon basin. Based on seismic interpretation and comparison with published works from the southward continuation of the PFB into Peru and Ecuador, three main across-strike, structural zones include:

1. The 20-km-wide, Western structural zone closest to the thrust front of the Colombian Andes that is characterized by inversion of older, Jurassic half-grabens during the late Miocene;
2. The 45-km-wide, Central structural zone characterized by moderately-inverted Jurassic half-grabens;
3. The 120-km-wide, Eastern structural zone characterized by the 90-km-wide, N-S trending Caquetá arch.

Structural traps for hydrocarbons are more common in the Western and Central zones while stratigraphic traps are more frequent in the Eastern structural zone.

The five mainly clastic tectonosequences of the PFB include:

1. The Lower Cretaceous pre-foreland basin deposits;
2. The Upper Cretaceous-Paleocene foreland basin deposits;
3. The Eocene foreland basin deposits related to the early uplift of the Eastern Cordillera;
4. The Oligocene-Miocene underfilled, foreland basin deposits;
5. The Plio-Pleistocene overfilled, foreland basin deposits.

Bio:

Paul Mann, University of Houston

Paul earned a BSc from the Oberlin College and a PhD from the State University of New York at Albany, both degrees in Geology.

He currently is Professor of Geology at the Dept. of Earth and Atmospheric Sciences, University of Houston, where he teaches, researches and supervises grad and undergrad students, and service to the EAS Dept. and other groups. He has also operated an oil industry-funded research group since 2005.

Paul is a member of AAPG, GSA, AGU, SEG and HGS.