Quantitative Seismic Interpretation of Multicomponent Data for Reservoir Characterization in the Middle Magdalena Valley Basin, Colombia

Velasquez, Antonio J.¹ and Davis, Tom L.
¹[email protected]

For the first time in Colombia the structural and quantitative interpretation of modern three-dimensional multicomponent (3D-3C) seismic data enables a geometric description, a kinematic interpretation of the structural styles, and the facies distribution of the Mugrosa Formation, in a mature oil field of the Middle Magdalena Valley Basin (MMVB). The structural interpretation methodology involves a 3D fault-correlation and horizon picking for both PP- and PS-PSTM data volumes. Geometric attributes such as coherence and curvature were used to enhance the structural discontinuities. The main unconformity, called Middle Eocene Unconformity (MEU) was carefully interpreted, and an attribute-assisted interpretation of the reservoir was conducted in detail. While P-wave data provided most of the structural interpretation, converted-wave data provide a better understanding of the fault systems.

Traditionally, compressive thrust-propagation folds and tectonic inversion have been considered as the main mechanisms controlling the deformation in the MMVB. However, the new interpretation shown in this work provides a different structural concept that involves two major structural styles: 1. Under the MEU the Late Cretaceous and Early Paleocene deformation, dominated by east-verging thrust and partially inverted Mesozoic normal faults, is preserved. Associated folds exhibit a north-south strike, and their structural development is controlled by a long-lived structural element that dominates the area (the Infantas Paleo-high). 2. Northeast striking younger normal faults indicate younger local extension, which affects the entire Cenozoic sequence. Normal faults are the structural heterogeneities that most affect the geometry of the reservoir compartments in the field. This normal faulting oriented oblique to the maximum horizontal stress, together with the associated folding, can arise from a left-lateral shear deformation that creates a local trans-tensional regime. In addition, Upper Eocene - Early Oligocene syn-tectonic deposits are also documented in this work, dating the last episode of deformation associated with the paleohigh uplift.

Further, a elastic inversion of acoustic impedance and Vp/Vs ratio performed using the PP and PS volumes and the sonic logs available, allowed the characterization of stratigraphic features within the Mugrosa Formation, in particular some channel geometries that are interpreted as part of a meandering fluvial system.

AAPG Search and Discovery Article #90166©2013 AAPG International Conference & Exhibition, Cartagena, Colombia, 8-11 September 2013