Structural Linking of the Recetor and Piedemonte Areas, Eastern Cordillera Fold and Thrust Belt, Colombia: Implications for Additional Hydrocarbon Accumulations
Frontal thrusts sheets in the Eastern Cordillera fold and thrust belt host the prolific fields of Cusiana, Cupiagua/Recetor complex, and more recently, the producing thrust sheets in the Piedemonte area to the north. All these fields produce from naturally fractured, low porosity sandstone reservoirs of the Paleogene Mirador, Barco and Upper Cretaceous Guadalupe Formations.
The deformation style and orientation of producing structures change from the Recetor area to the Piedemonte area to the north. A new interpretation of this area, using overlapping 3D seismic surveys, shows how the two areas link structurally. Surface and well data, including image log data, provide additional key constraints. The deeper structural elements are poorly imaged in the transition area, thus requiring iterative structural modeling to aid in developing a robust interpretation. Interpretation of sections that are constrained by the wells yields a balanced and admissible fault network. The network of 2D sections provides an interpretation template for the the 3D seismic volume.
Surface structural trends show only a slight change in strike orientation of the frontal structures in this area, and an average dip slip direction can be inferred. In contrast, the deeper thrust sheets show a distinct change in trend and style of thrust sheets. Recetor wells produce from the frontal anticline of a single long thrust sheet, which is broken by backthrusts of varying displacement. In contrast, just north of transition, Volcanera/Dele wells produce from the stacked thrusts typical of the Piedemonte area. The change in trend and distinct inferred slip directions at deeper levels suggest a component of shortening along strike in the transition zone between these two domains. The seismic data show along-strike folding that supports this interpretation. The change in the shape of the Nunchia syncline reflects the change in style and trend of the deeper thrust sheets. Consistency of shortening in the main dip direction combined with the along-strike effects produce culminations in the different thrust sheets, some of which are producers and some are prospective for hydrocarbons. The combination of 2D and 3D balancing, with forward modeling, insures that the model is valid. The 3D structural model allows reservoir estimates with a range of uncertainty and serves as a robust, structurally tested guide to further drilling.
AAPG Search and Discovery Article #90142 © 2012 AAPG Annual Convention and Exhibition, April 22-25, 2012, Long Beach, California