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Joseph A. Cartwright
Episodic basin-wide fluid expulsion from geopressured shale sequences in the North Sea basin
Geology (Boulder) (May 1994), 22(5):447-450
Abstract: Index Terms/Descriptors: Latitude & Longitude:
GeoRef, Copyright 2004, American Geological Institute.
A proposed general model for the episodic dewatering of thick shale successions is based on the recognition of a pervasive polygonal extensional fault network developed in the dominantly fine grained lower Tertiary of the North Sea basin. Seismic data show that the faults are arranged in stratigraphically bound structural units (tiers) that are delimited vertically by almost undeformed condensed sections, and are restricted in distribution to the lowest permeability slope and basin- floor facies. I propose an episodic three-stage mechanism to explain the fault genesis, involving (1) the development of basin-wide overpressured compartments, (2) a density inversion between the overpressured units and the overlying seal, and (3) natural hydraulic fracturing, pressure bleed-off, and resealing of the pressure compartment leading to a repeat of the cycle.
Atlantic Ocean; basins; Cenozoic; clastic rocks; compaction; dehydration; diagenesis; European Atlantic; extension faults; faults; geophysical methods; geophysical surveys; geopressure; lower Tertiary; mudstone; naturally fractured reservoirs; normal faults; North Atlantic; North Sea; periodicity; petroleum; porosity; sedimentary rocks; seismic methods; shale; surveys; Tertiary; three-dimensional models
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