Variability in Structural Style and Fault Interaction in Submarine Compressional Structures: a Case Study from Offshore Venezuela

Nevado, Nieves¹, Asdrubal Bernal², Cesar Vasquez¹ (1) PDVSA Intevep, Caracas, Venezuela (2) PDVSA-Intevep, Caracas, Venezuela

Detailed structural characterization of the petroleum system elements is an important component in the evaluation of the hydrocarbon potential in exploration areas. In this study, the structural interpretation and kinematic evolution of a frontier area offshore Venezuela is done through use of 3D seismic attributes in depth, log information data and balanced cross sections.

Visualization and interpretation of the data show various structures with trends of axial surface changing from NW-SE to NE-SW, with the structural style and relief changing rapidly along the study area. The structures in the SW and NE of the study area are symmetrical and asymmetrical anticlines, respectively, of lower to middle Miocene age, interpreted to be formed by an interference of fault-bend fold structures responding to a stack of low-angle ramps developed during and after periods of tectonic subsidence. The geometry of syn-tectonic sediments and the low quality of the seismic data in the core of these anticlines, however, allow the interpretation of these structures as detachment fold anticlines. The structure in the central part of the study area is an asymmetrical anticline, with the forelimb strongly eroded. This structure is interpreted to be formed by episodes of limb rotations, folding older fault-bend and inversion structures.

All the observations presented above propose individual but kinematic interacting faults in 3D. This interaction can be recognised from strata geometry. In addition, seismic features suggest the possibility of hydrocarbon accumulation in these anticlines, forming structural traps or a combination of structural and stratigraphic traps.