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