Petroleum Geology of NW Europe: 50 Years of Learning – Proceedings of the 8th Petroleum Geology Conference
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New exploration discoveries in a mature basin: offshore Denmark
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Published:January 01, 2018
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CiteCitation
Graham Goffey, Mark Attree, Paul Curtis, Fiona Goodfellow, Jeremy Lynch, Dave Mackertich, Tobore Orife, William Tyrrell, 2018. "New exploration discoveries in a mature basin: offshore Denmark", Petroleum Geology of NW Europe: 50 Years of Learning – Proceedings of the 8th Petroleum Geology Conference, M. Bowman, B. Levell
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Abstract
In 2011, two discoveries were drilled by PA Resources in the Danish sector. The Broder Tuck 2/2A wells were drilled on a thrusted anticlinal structure, downdip of the apparently small U-1X gas discovery. The wells found an excellent quality gas reservoir within an interpreted Callovian lowstand incised valley containing braided fluvial and marginal-marine sandstones. A top and base seal are provided by mudstones of the over- and underlying transgressive systems tracts respectively. The development of a base seal is key to the presence of a potentially commercial resource downdip of a relatively unpromising old well.
The Lille John 1/1B wells were then drilled on a salt diapir on which 1980s wells had encountered shallow oil shows. Lille John 1 found slightly biodegraded 34° API oil in Miocene sandstones at the uncommonly shallow depth of −910 m true vertical depth subsea (TVDSS). The reservoir is full to spill, whilst the trap developed intermittently through latest Miocene–Late Pleistocene times. It is interpreted that a deeper Chalk accumulation temporarily lost seal integrity owing to glacially induced stress or overpressure triggering top-seal failure or fault reactivation during and after latest Pleistocene diapir inflation. The wider hydrocarbon exploration implications of glaciation on stress, pore pressure and trap integrity appear to be underappreciated.
- Atlantic Ocean
- Callovian
- Cenozoic
- Central Graben
- clastic rocks
- Cretaceous
- Denmark
- diapirs
- discoveries
- Europe
- geophysical methods
- glaciation
- incised valleys
- Jurassic
- Mesozoic
- Middle Jurassic
- Miocene
- natural gas
- Neogene
- North Atlantic
- North German Basin
- North Sea
- offshore
- petroleum
- petroleum exploration
- reservoir properties
- sandstone
- Scandinavia
- sedimentary rocks
- seismic methods
- structural traps
- Tertiary
- traps
- Upper Cretaceous
- Viking Graben
- Western Europe
- Kraka Field
- Lille John Field
- Broder Tuck Field