André Tonetto Picarelli1, Jorge Arguello2, Vitor Abreu3
(1) Perez Companc de Venezuela SA, Caracas N/A, Venezuela
(2) Perez Companc de Venezuela SA, Caracas, Venezuela
(3) ExxonMobil, Houston, TX
The Mata-Araibel oil field records Miocene fluvial to shallow marine sedimentation (Merecure and Oficina Formations) in the distal zone of the Eastern Venezuelan foreland basin. Based on the stacking patterns, sand body geometry and core data, these formations were divided in three lower to middle Miocene tectonically enhanced second order cycles. These three second-order cycles were sub-divided in eleven third order sequences, composed by forth and fifth order events.
The shallow marine ramp setting, distal to the collision front of the foreland, allowed the development of multiple high frequency sequence boundaries within a broad estuarine system. The main reservoir rocks were deposited during 5th order lowstand and transgressive systems tracts. At the beginning of the foreland phase (Chattian 2 to Burdigalian 1), low accommodation rate caused the development of incised valleys during lowstands, whereas in the upper part of the section (Burdigalian 3 to Langhian 2) valley incision decreases due to the higher accommodation space and sequence boundaries are represented by estuarine (channels and tidal bars) and platform (sand ridges) sediments, overlying offshore muds.
According to this model, isolated transgressive sand ridges and tidal bars encased in estuarine muds constitute the main targets for by-passed oil. Major (third order) flooding events form regional seals, isolating packages of stacked reservoirs, defining flow units in the field.
AAPG Search and Discovery Article #90906©2001 AAPG Annual Convention, Denver, Colorado