Philip Sedore

B.Sc. (Honours) Thesis

PRELIMINARY 1D MODELLING APPROACH TO THE INVESTIGATION OF MESOZOIC SOURCE ROCKS IN SEVERAL OFFSHORE NEWFOUNDLAND BASINS

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The current understanding of the petroleum systems offshore Newfoundland rely on one source rock interval, the prolific Egret Member of the Rankin Formation. To reduce exploration risk, further investigation of the distribution, potential, and maturation of other possible source rocks is needed. Lower Jurassic source rocks are observed in outcrop at Portugal (the conjugate margin to Newfoundland) and, considering the similarity of the sedimentological record from these two sides of the Atlantic, we hypothesize that a similar source rock occurs offshore Newfoundland.

This preliminary study focuses on the 1D modelling (PetroMod™) of the Lower Jurassic interval offshore Newfoundland using previously published and newly acquired geochemistry datasets, i.e. Total Organic Carbon (TOC) and Rock-Eval pyrolysis (kerogen characterization) from five wells (Bittern M-62, Coot K-56, Cormorant N-83, Golconda C-64 and Murre G-67). Three additional wells, without new geochemical data (Osprey H-84, Skua E-41, and Spoonbill C-30) are also assessed. Boundary conditions such as paleo-water depth (PWD), surface-water interface temperature (SWIT), and basal heat flow are vital controls of the model. PWD and SWIT are inputted based on the modeler’s interpretation of the dataset; basal heat flow is calibrated using vitrinite reflectance and well temperature data. These are used in conjunction with the main lithology, biostratigraphy, and geochemical inputs (available at NRCan’s BASIN database) to create models that characterize the targeted intervals and to determine their potential as a hydrocarbon source rock.

The obtained geochemical results suggest that the investigated interval in the studied wells is dominated by type III-IV kerogens and have low TOC values (< 1 %). Regarding thermal maturity, while considering the poor reliability of the dataset, Tmax values suggest that these intervals are within the oil generation window. Our 1D models advise that the Lower Jurassic reaches temperatures related to this early maturity window around the Late Jurassic. Further studies are needed to verify and extend our conclusions to other areas offshore Newfoundland.

Keywords: Lower Jurassic, offshore Newfoundland, source rock, petroleum system modelling, conjugate margin
Pages: 79
Supervisor: Grant Wach / Ricardo Silva