PETROX 2005Group 1•Morten Lorentzen•Ole Jørgen Birkenes•Olumide Gbadamosi•Huijuan Yu•Wijaya Zein
Wessex Basin
Includes the largest known onshore oilfield in W-Europe
Preservation of oil-accumulations originally sited in Mesozoic tilted fault-blocks.
Key elements in petroleum geology
• Source
• Reservoir
• Seal
• Trap
• Timing
• Maturation
• Migration
Source Rock Features in West Cliff Lyme Regis.
• Marine environment (grey colour).
• Early Jurassic age.
• Organic sedimentary deposits which forms the hydrocarbon under right conditions.
• Laminated shale deposit with many fossils. Low oxygen environment.
• 6% organic contents
• Organic type: Kerogen II
•Dips at 2 degrees to the East.
Limestone (wackestone)
Black Shale (mudstone)
Limestone (wackestone)
Black Shale (mudstone)
Geological Log InterpretationFor WestCliff source rock
Limestone, porosity :5-10%
Shale, porosity :2%
Sherwood sandstone
•Triassic
•Colour
•High porosity
•Dip,5-10 deg East
•Fault
Sandstone with thin shalelayers
Porosity between 30-40%
Oil Migration