Application of Advanced Technologies for Improving the Petroleum Systems Modeling in Foreland Fold-and-Thrust (FFT) Belts: The Llanos Basin Case Study

Abstract

Foreland fold-and-thrust (FFT) belts are geological complex settings for hydrocarbon exploration. However, they are very prospective areas. We describe here some advanced technologies used to improve the petroleum systems modelling in FFT, particularly for coupling the kinematics of deformation with thermal, maturation and expulsion modellings and for constraining charge history. Erosion and uplift are two competing factors that can delay hydrocarbon generation in FFT. In order to address these challenges, it was developed the Fetkin software which is a C++ program for forward modeling thermochronological ages on a two-dimensional geological cross section. Modeled ages for various thermochronometers are computed from time–temperature histories that result from coupling the modeled kinematics of deformation obtained from commercial software for balanced reconstructions and a finite element computation of temperatures. In this way, in the Llanos Basin it was possible to constrain simultaneously both, the thrust structural and thermal evolution. High resolution geochemistry techniques as taxon specific/age-related biomarkers, Diamondoids C13 isotopes and hydrous pyrolysis can be integrated in order to characterize and decipher complex charge histories in FTT settings. In the Llanos Basin taxon specific/age-related biomarkers extracted from oils and hydrous pyrolysate products, allowed to identify contributions from three late Cretaceous organofacies, one early Cretaceous source and one active Tertiary source. For the other hand, migration pulses related to the beginning, peak and end of the oil window could be recognized for each source identified using C13 isotopes in Diamondoids. Post filling events can be defined using a combination of a detailed quantitative molecular composition characterization with API gravity values. In the Llanos Basin, this approach indicates that the variable mixing ratios between severely biodegraded oils, and later fresh-oil charges across the study area is the principal control on the quality and economic value of the accumulations. At sites where fresh oil is not currently overprinting initial biodegraded charges and thus, n-alkanes compounds have been removed, the relative abundances of polycyclic aromatic hydrocarbons, alkyladamantanes and bicyclic sesquiterpanes might play the most significant role; implying that the controlling factor is the extent of biodegradation of the original relative to the later fresh oil charge.

AAPG Datapages/Search and Discovery Article #90291 ©2017 AAPG Annual Convention and Exhibition, Houston, Texas, April 2-5, 2017