A New Kinematic Tool for Petroleum System Modeling in Complex Structural Settings: Application to the Andean Foothills

Abstract

Petroleum system modeling is today recognized as a critical step in exploration workflows. However, fold and thrust belts are typical regions where classic basin modeling tools do not accurately manage the combination of lateral and vertical tectonic displacements. These complex areas where hydrocarbon expulsion from source rocks can be prior or simultaneous to compressive tectonics require more accurate modeling approaches integrating active faulting, folding and fluid flow. The basin burial and geometry reconstruction, fault connectivity and fluid movements should thus account for the actual horizontal deformation through time, which is impossible with a regular backstripping approach. This work introduces a 2D kinematic tool specifically designed to meet this objective. Starting from present day section digitalization, KronosFlowTM aims at producing rapidly consistent geological scenarios for basin modeling purposes. The first challenge of this approach is related to the number of restoration steps to provide as basin modeling requires a detailed kinematic scenario with, at minimum, a basin geometry at the end of each simulated layer deposition. Combining several geometrical and mechanical methods, the tool thus focuses on ergonomics to enhance productivity and afford multiple scenarios testing. The second challenge is linked to the mesh preservation through time that we believe essential for mass balance. In this regard, a new meshing technology has been developed to track sediments deformation while being compatible with a simulator able to take advantage of an accurate description of the basin evolution through time. Running on unstructured meshes and accounting for lateral displacement, this basin simulator uses the produced kinematic scenario for the forward simulation of heat transfer, pressure, hydrocarbon generation, migration and accumulation. Faults impact on fluid flow is assessed through an implicit modeling of the gouge and damage zones properties through time. An application case from the Andean foothills illustrates the applicability of these new technology and workflow. Preliminary structural reconstruction work detailing the main deformation phases of the area is used to guide the complete kinematic scenario made of more than fifteen steps. Forward basin simulation is then run and the model, calibrated to available well data, allows testing the impact of thrusting on maturation, migration pathways and hydrocarbon charge and quality. Several scenarios are elaborated, contributing to reduce the exploration risk.

AAPG Datapages/Search and Discovery Article #90326 © 2018 AAPG Latin America & Caribbean Region, Optimizing Exploration and Development in Thrust Belts and Foreland Basins. Santa Cruz de la Sierra, Bolivia, June 6-8, 2018