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Petroleum System Modeling in Faulted and Structurally Complex Areas: Application of an Innovative Workflow

Arnaud Arbeaumont¹ and Adrian Vargas²
¹Beicip, Rueil Malmaison cedex, France
²PDVSA – Temis++ Consortium, Venezuela

The assessment of petroleum systems using deterministic basin modeling techniques is nowadays widely used in exploration. As the strain on oil resources increases and the era of easy oil is over, exploration is now moving to more complex, riskier areas to unveil new resources. Some of these challenging areas being the complex continental compressive settings where standard basin modeling tools cannot be applied properly.

Leveraging the latest advances in basin modeling technologies is necessary to ensure predictive results in complex structural areas and heavily faulted environments. Next-generation basin modeling tools allow combining structural restoration and kinematic modeling tools with forward basin simulation for offering an accurate control on both basin deformation and flow across and along fault planes, leading to predictive models.

Such techniques were applied on this 80,5 km long regional transect from the South Andean flank, Southwest of Venezuela, in order to thoroughly quantify the coupled impact of kinematic deformation and fault patterns on pressure and related variables such as compaction or effective stress, and on kitchen areas, including maturity levels, generated hydrocarbon volumes as well as expelled hydrocarbon fluids characterization.

First step of this work was to perform the restoration of the 2D section, combining subsidence, erosion and syntectonic sedimentation in a deformation scenario generating imbricated structures, duplex and verging thrusts. Seven main tectonic events were considered, from Oligocene to Present Day.

Second step of the workflow was to generate an unstructured mesh which would honour the set of restored geometries while deforming continuously through time, which is a prerequisite for consistent forward modeling afterwards. In this workflow fault planes are implicitly meshed by the software, both core and damage zones being taken into account.

Finally the deformed mesh was passed to TemisFlow basin modeling software where it was populated with facies and source rock information to generate a consistent lithostratigraphic model. Petrophysical properties were input as well. Full computation accounting for coupled compaction, water flow through Darcy's law, heat transfer and hydrocarbon generation and expulsion effects is carried out. Simulation is performed using the next-generation Arctem calculator from IFPEN Group able to handle unstructured meshes as well as the internal boundaries associated to the fault network. Calibration has been reached using well data available in the area.

Simulation results outline the dramatic impact the complex deformation history has on maturity levels and generated volumes as well as the critical effects the fault network has on pressure regimes, highlighting the added-value of this workflow combining restoration & basin modeling technologies in complex structural settings.

AAPG Search and Discovery Article #120098©2013 AAPG Hedberg Conference Petroleum Systems: Modeling the Past, Planning the Future, Nice, France, October 1-5, 2012