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Hydrodynamic stagnation zones; a new play concept for the Llanos Basin, Colombia

Mark Person, David Butler, Carl W. Gable, Tomas Villamil, David Wavrek and Daniel Schelling
Hydrodynamic stagnation zones; a new play concept for the Llanos Basin, Colombia
AAPG Bulletin (January 2012) 96 (1): 23-41

Abstract

Hydraulic heads from a calibrated, three-dimensional, constant-density, ground-water-flow model were used to compute Hubbert oil potentials and infer secondary petroleum migration directions within the Llanos Basin, Colombia. The oil potentials for the C7 reservoir show evidence of the development of two hydrodynamic stagnation zones. Hydrodynamic effects on secondary oil migration are greatest in the eastern Llanos Basin, where structural slopes are lowest and local hydraulic-head gradients drive ground-water flow westward down structural dip. The Rubiales field, a large oil reservoir within the eastern Llanos Basin with no structural closure, is located at the edge of one of these stagnation zones. This oil field hosts heavy oils (12 degrees API) consistent with water washing and biodegradation. The best agreement between model results and field conditions occurred in an oil density of 12 degrees API, suggesting that the Rubiales field position is in dynamic equilibrium with modern hydraulic and oil density conditions. Cross sectional ground-water-flow models indicate that the most likely explanation of observed underpressures are caused by hydrodynamic effects associated with a topography-driven flow system. Late Miocene to present-day ground-water flow likely was an important factor in flushing marine connate porewaters from Tertiary reservoirs. Ground-water recharge along the western margin of the basin could help explain the observed low-temperature gradients (20 degrees C/km). However, upward flow rates were not high enough to account for elevated temperature gradients of 50 degrees C/km to the east.


ISSN: 0149-1423
EISSN: 1558-9153
Coden: AABUD2
Serial Title: AAPG Bulletin
Serial Volume: 96
Serial Issue: 1
Title: Hydrodynamic stagnation zones; a new play concept for the Llanos Basin, Colombia
Affiliation: New Mexico Institute of Mining and Technology, Department of Earth and Environmental Sciences, Socorro, NM, United States
Pages: 23-41
Published: 201201
Text Language: English
Publisher: American Association of Petroleum Geologists, Tulsa, OK, United States
References: 50
Accession Number: 2012-059277
Categories: Economic geology, geology of energy sourcesHydrogeology
Document Type: Serial
Bibliographic Level: Analytic
Annotation: Includes appendix
Illustration Description: illus. incl. block diags., sects., 2 tables, sketch maps
S04°00'00" - N12°15'00", W79°00'00" - W67°00'00"
Secondary Affiliation: Los Alamos National Laboratory, USA, United StatesGrupo C and C Energia, COL, ColombiaPetroleum Systems International, USA, United StatesStructural Geology International, USA, United States
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by American Association of Petroleum Geologists, Tulsa, OK, United States
Update Code: 201231
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