Basin Modeling Study Research Articles

Consequences of foreland basin development on thinned continental lithosphere: Application to the Aquitaine basin (SW France)

We present an analysis of the consequences of foreland basin development on thinned continental lithosphere, inherited from pre-orogenic phases of extension. Bathymetry at the transition from pre-orogenic extensional basin to foreland basin and compaction of pre-orogenic sediments contribute to the accommodation space for foreland basin sediments and thrust loads. In addition, the extension-induced transient thermal state of the lithosphere, results in ongoing thermal subsidence, and a flexural rigidity which changes through time. Quantitative modelling of the phase of extension and the foreland basin stage of the Aquitaine basin (southern France) shows that the inherited transient thermal state of the lithosphere contributes significantly to (1) the total foreland basin depth and width, (2) the post-compressional subsidence history, and (3) the cratonward onlap pattern. Accounting for the thermo-mechanical effects of pre-orogenic extension significantly reduces the estimates of both the flexural rigidity (30–43% for the Aquitaine basin) and the required topographic or thrust load (40% for the Aquitaine basin) at foreland basins. Emplacement of thrust loads below sea level, as expected in a pre-orogenic extensional basin setting, further reduces the required topographic load. This sheds light on the wide range of flexural rigidity values reported for continental lithosphere from foreland basin modelling studies, and explains, in many instances, the inferred ‘hidden load’ or subsurface load in flexural modelling studies at foreland basins. The present study has shown that pre-orogenic extension phases significantly affect the record of vertical motion and the stratigraphy of the Aquitaine basin and is probably important for foreland basin evolution in general.

Basin Modeling: Facts and Hopes

Basin modeling has been recognized as a useful tool for helping evaluate the petroleum potential of a basin or a prospect, as it is a unique way to integrate various geological and geochemical phenomena involved in petroleum formation and occurrence. However, the authors knowledge of the various phenomena remains partial, and simplifications must still be made when undertaking a basin study. A typical basin modeling study will encompass the reconstruction of the structural evolution of the basin, the simulation of the petroleum generation, and its subsequent expulsion and migration from the source rocks toward traps. These various phenomena will have to be quantified, involving various equations and their corresponding computer solutions. A major challenge that remains is the description of petroleum fate in tectonically complex zones including salt diapirs. This will require the understanding of fluid movements within faults or fluid movements induced by intense sediment deformation, and permeability changes due to stress related rock fractures. Another challenge includes a satisfactory prediction of diagenetic phenomena and petroleum evolution due to thermodynamic changes or biochemical degradation.

Hydrocarbon generation in southern Sicily. A three dimensional computer aided basin modeling study

A three-dimensional computer-aided basin modeling study was performed in order to determine timing and spatial distribution of hydrocarbon (HC) generation in southern Sicily. The entire information concerning the geologic evoulution such as age, thickness, lithology and porosity of individual sedimentary layers, estimates on paleobathymetry and sediment/water interface temperatures, initial physical and thermal properties of various lithologies, heat flow and particularly type and amount of organic matter was used to construct a conceptual model and to determine the necessary input parameters. The simulation of basin evolution resulted in a very detailed and comprehensive definition of the thermal history of the study area. Subsequently, the thermal history of the Noto source rock throughout the entire study area was used to define the HC generation potential. The latter was not elaborated with the help of maturity data but utilizing a kinetic model. The simulation results showed that the main phase of oil generation was during the last 5 ma when a foredeep basin was created in front of the overthrust sheets. Here very thick Pliocene-Pleistocene sediments were deposited. The rapid burial caused a quick temperature increase, i.e. high heating rates which initiated the onset of oil generation at relatively low maturity levels. Furthermore it also caused an early expulsion of immature heavy oil from the Noto source rock.