Kevin J. DesRoches

B. Sc. Honours Thesis

A Subsidence, Compaction, Pressure, Temperature, and Maturity History of the Hibernia B-08 Well, Grand Banks, Newfoundland

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The Jeanne d'Arc basin is one of several of Late Triassic basins in Atlantic Canada, some of which contain significant quantities of hydrocarbons. The Jeanne d'Arc basin has extensive overpressuring associated with the Fortune Bay Shale. Numerical modelling of data from one well, Hibernia B-08, promotes an understanding of the nature of the overpressuring in the Hibernia field, and the timing of organic maturation of the major source unit, the Egret Member. Mathematical models of temperature, pore pressure, and hydrocarbon kinetics, applied to a series of stratigraphic columns derived by decompacting a generalized version of the present-day stratigraphy, represent the dynamics of the well site through time. Overpressure in the well does not appear to relate to rapid compaction effects, because burial history models show that subsidence and sedimentation rates have been consistently low for the last 60 Ma, placing an upper limit on the age of overpressure development. Shale transformations, which release water and are often cited as producers of overpressures, commonly occur at burial depths between 2000 and 3500 m. Rapid subsidence in the Late Jurassic and the Early Cretaceous buried much of the underlying shales below 3500 m before 60 Ma. Thus hydrocarbon generation, which began at 75 Ma, and continues today, is the source of overpressure in the area of Hibernia B-08.

Kwywords: Jeanne d'Arc; basin analysis; compaction; maturity; pressure; overpressure;
model; heat flow
Pages: 72
Supervisor: Mark Williamson