AAPG - Technology Highlights: 3D TecLink
3D TecLink
A new Approach in Petroleum Systems Analysis to link Basin- and Structural Modeling
Friedemann Baur and Thomas Fuchs, IES Integrated Exploration Systems (IES)
Introduction
Basin Modeling is widely used in the petroleum industry and governmental geological surveys for global hydrocarbon reserve assessments and for quantifying geoprocesses and related risks. But many of the world’s interesting exploration areas are characterized by structurally complex geological histories and are difficult to analyze. Up to now there has been no technique, which links Structural Modeling techniques with Basin Modeling in four dimensions (space and time) to allow for an adequate petroleum systems analysis.
Figure 1. Structural input data above and the corresponding PetroMod® input model below.This new technique is called “3D TecLink” and has been developed by IES® (Integrated Exploration Systems GmbH). The technique enables the customer to assess and analyze a 3D petroleum system through time, dominated by compressional geological settings by using the complete range of petroleum generation, migration and accumulation tools in IES software PetroMod®. PetroMod® 3D TecLink is an add-on package to IES' PetroGen/PetroFlow 3D packages. Data can be loaded from all major commercial 3D structural modeling packages.
Methodology
The 3D TecLink-technique has been developed and for the first time applied while building a highly complex model for a pilot project located in the fold and thrust belts of the Sub Andean orogeny amidst the Sierras Subandinas, Bolivia. Prior to 3D, this unique technology had been put into practice and applied in a simplistic way to many locations worldwide in the context of 2D sections. The TecLink technology is capable to perform full PVT-controlled, 3-phase, n-component petroleum migration simulations in any type of structural geological settings. The aim of this pilot project was to transfer the already existing 2D TecLink technology (realized within the PetroBuilder®, which is an add on for the 2D PetroGen/Flow packages of PetroMod®), to a 3D model. This is the first time at all that this technology has been set to practice to perform an all-comprehensive petroleum systems analysis in a 3D compressional geological setting.
Sierras Subandinas, Bolivia
The general geology of the study area can be summarized as follows:
The present day foreland basin exists since the Early Miocene and is characterized by north-northeast trending anticlines. Sedimentary sequences of up to 8 km have been deposited from Early Ordovician up to Late Pliocene. The compressional regime and thin-skin tectonic occurred around 7 Mabpd. Well known type II to type III source rocks are the Middle Devonian Los Monos, the Early Devonian Icla and the Silurian Kirusillas Formation with faire TOC contents. Most important reservoir intervals are the fractured Early Devonian quartzites of Huampampa and the Late Devonian Iquiri Formation with good quality; potential reservoirs are the Santa Rosa, Ichoa and Machareti formations.
Figure 2. Multiple depth values, sub-models and a paleo-model at the beginning of thrusting (from left to right). Used data to evolve this pilot study have been provided by Repsol YPF and comprise the present-day geometry, 14 structural restored paleo-sections as well as temperature, maturity and pressure calibration data along key-wells. All available geometrical and geological data have been imported into PetroMod® to build the model (Figure 1).
The conventional simulation approach in basin modeling is to perform first back stripping to recalculate the initial depositional thicknesses of a layer by applying a decompaction rule. After decompaction a forward modeling simulation will be performed to calculate the entire temperature and pressure history. The present day geometry and the geophysical parameters of the assigned lithologies make up the most important input data set to perform a deterministic, forward-modeling approach and to calculate the present day geometry.
In case of structural movements through time additional reconstructed paleo models are needed to understand the kinematics and its impact on the geometrical evolution of the basin. Therefore, the reconstructed paleo models act as additional input geometries for the forward-simulation. During the period of time of normal sedimentation the forward simulation technique has not changed to a normal routine. But for the ages of defined paleo models/sections the compaction is not calculated any more because the thickness has already been predefined in the input. The only parameter, which needs to be calculated, is the vertical effective stress from which all other parameters can be derived.
Figure 3. Calculated transformation ratio, temperature and vitrinite reflectance for present day situation (from left to right).Models, which undergo significant shortening, comprise multiple depth values for the same layer, due to thrust faults and its layer-doubling effect. This causes problems during the simulation but can be avoided by subdividing the model and all paleo models into submodels (blocks), each of which retain their structural integrity but are treated as one model for the simulator (Figure 2).
Conclusion
The focus of this study lay on temperature and pressure developments through time and the model results depict very well the observed distribution of these parameters. Vitrinite reflectance and temperature have been calibrated for all available data; pressure, permeability and porosity have been calibrated for all wells based on mud-weight data and in situ measurements (Figure 3). The calculated distribution of hydrocarbon gets very close to the known present day distribution, but has not been calibrated yet.
Therefore, it can be said that parts of the Subandean Fold and Thrust Belt have been modeled successfully and for the first time with full pressure resolution in a basin modeling study.