Valle, Tommaso (2014) North Atlantic Jurassic petroleum systems: source rock characterization in a conjugate margins perspective of the segment Portugal-Newfoundland. [Magistrali biennali]
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The North Atlantic Mesozoic rifting evolved with two main phases: Late Triassic into Early Jurassic and Late Jurassic through Early Cretaceous. This rifting segment between Newfoundland and Iberia can be described as a poor-magma example and its asymmetrical development, due to the multiphase northward propagation caused the differences in the stratigraphy of conjugate margins. The first analysis concerned the oil data: all samples were divided into families with statistical treatment, in according with their geochemical parameters and biomarkers observed in the gas chromatograms. After the oils division, each family presented a geochemical description that led to identify a possible source environment. The source rock identification was done through the Rock-Eval dataset and a subsequent quality control of the data for some selected wells. Several source rocks levels were identified, mainly from Kimmeridgian time, with good original naphthogenic properties calculated. A big part of the project was represented by the realization of maps for the Jurassic and Early Cretaceous stages, using paleo-geographic modeling from ENI contractors and with free-user software, called GPlates, These reconstructions allow to recognize, through geodynamics evolution of the margins, the source rock original depositional environments. In addition to the reconstructions and source analysis, some 1D models were executed to evaluate the potential of the source rocks in terms of hydrocarbons generation and expulsion. The software called PetroMod was used to build burial history and some plots of temperature and vitrinite reflectance versus depth. These modeling were done for few wells because required many data such as completely stratigraphy, lithology and temperature, not always available in the published summary reports. The geochemical oil-source correlations and the interpretations of the paleoenvironments led to identify two main time-steps for the generation of hydrocarbons on both side of North Atlantic Ocean: Oxfordian-Kimmeridgian source rock levels with differently sediment inputs between the basins (marine in Newfoundland, more continental in the Porcupine Basin) and deeper layers dated Sinemurian-Plienasbachian, with black shale or organic-rich facies deposited in carbonate intra-platform basins along Portuguese and Canadian coast.
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