New Approach for Understanding the Paleogeography of the Maturin Sub-Basin During Early - Middle Miocene in North Monagas State - Venezuela

Gilberto J. Sanchez, Anahy Finno, Linda Montilla, Noelia Batista, and Oswaldo Guzman
Exploration, PDVSA, Puerto La Cruz, Venezuela

Maturin Sub-Basin in Eastern Venezuela, is a very well known province because its giants oil accumulations associated to Oligocene shallow marine reservoirs. However, there are other rocks with potential to act as an hydrocarbon reservoir in the Miocene section that have been less studied. These sediments were deposited in a deep environment inside a foreland basin with a complex tectonostratigraphic evolution that controlled the facies distribution and geometry of the sedimentary bodies. One reservoir deposited on this environment was tested on the Amarilis area, were 40° API condensate was discovered during the 90s.

To understand the reservoir distribution inside the basin and its relationship with the structural evolution, different techniques were integrated. This includes sequence stratigraphic analysis and structural modeling considering seismic-well correlation and interpretation, bioestratigraphyc integration and sedimentological description among others.

Balanced cross sections were constructed and modeled to propose a kinematic evolution, considering thermal calibration, uplift-erosion rate and subsidence-deposition history. Based on partially restored sections paleotopographic and paleogeographic 3D surfaces were constructed for Middle Miocene (Early Miocene top). Finally, sediment transport directions and depocenters location were interpreted in shelf and deep basin environments.

The main Middle Miocene foredeep depocenter is actually located bellow and South of the Furrial thrust sheet. Three main transport directions were established from Northwest (uptilfted thrust belt), West and South (stable margin). The proposed model suggest that deposition advanced progressively toward East - Southeast during Middle Miocene.

AAPG Search and Discovery Article #90078©2008 AAPG Annual Convention, San Antonio, Texas