AAPG Bulletin, V. 84, No. 6 (June 2000), P. 741-764.

Fold-Evolution Matrices and Axial-Surface Analysis of Fault-Bend Folds: Application to the Medina Anticline, Eastern Cordillera, Colombia¹

Mark G. Rowan² and Roberto Linares³

©Copyright 2000. The American Association of Petroleum Geologists. All rights reserved.
¹Manuscript received April 15, 1998; revised manuscript received July 13, 1999; final acceptance November 15, 1999.
²Rowan Structural Consulting, 1633 D 4th Street, Boulder, Colorado 80302; e-mail: [email protected]
³Ecopetrol, Instituto Colombiano del Petroleo, Piedecuesta, Santander, A.A.4185, Colombia.
We thank Ecopetrol for sponsoring the research and providing the seismic data, originally acquired by Pennzoil, Exxon, Maxus, and Ecopetrol. CogniSeis Development (now Paradigm Geophysical) donated the Geosec® restoration and modeling software used to construct the fold-evolution matrices. The research was done at the Energy and Minerals Applied Research Center (EMARC) at the University of Colorado, where the first author was funded by an industrial consortium consisting of Agip, Amerada-Hess, Amoco, Anadarko, BHP, BP, Burlington, Canadian Oxy, CNG, Conoco, Enterprise, Exxon, Marathon, Maxus, Mobil, Occidental, Phillips, Shell, Texaco, Union Pacific, Unocal, and Vastar. Finally, we thank Chuck Kluth, Don Medwedeff, Karl Mueller, Bob Ratliff, Bruce Trudgill, Tomas Villamil, and Paul Weimer for their comments and contributions, and John Shaw for the invitation to contribute to this special issue.

ABSTRACT

The Medina anticline is a fault-bend fold located in the hanging wall of the Aguaclara fault along the southeastern thrust front of the Eastern Cordillera of Colombia, a petroleum province with giant fields. We employ a modified technique of axial-surface analysis using fold-evolution matrices, which helps define the subsurface geometry and thereby provides important constraints on trap geometry, modeling of hydrocarbon migration pathways, and prediction of reservoir quality.