Core and seismic observations of overpressure-related deformation within Eocene sediments of the Outer Moray Firth, UKCS

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doi: 10.1144/petgeo.8.2.141
Authors:Hillier, R. D.; Cosgrove, J. W.
Author Affiliations:Primary:
Ysgol Greenhill, Tenby, United Kingdom
Imperial College of Science, Technology and Medicine, United Kingdom
Volume Title:Petroleum Geoscience
Source:Petroleum Geoscience, 8(2), p.141-149. Publisher: Geological Society Publishing House, London, United Kingdom. ISSN: 1354-0793
Publication Date:2002
Note:In English. 40 refs.; illus., incl. strat. cols., geol. sketch maps
Summary:Cores from the Eocene Alba Field of the Outer Moray Firth, UKCS contain sandstone injections and bedding-parallel fibrous "beef" veins. Both of these features are associated with high fluid pressure and the process of hydraulic fracturing. The orientation of the hydraulic fractures (along which sand injection occurred, or calcite precipitated) was controlled by the interplay of the stress field and the intrinsic anisotropy of the sediments. Seismic sections indicate that sand injection occurred on a larger scale than is apparent from the cores. Interpreted dykes (400 m long by 30 m wide) emanate from the margins of the Alba channel sandstone along fault planes. An analogy is drawn between these dykes, and the peripheral dykes formed at the margins of laccoliths as a result of the flexing and subsequent fracturing of the overlying strata. "Decompacting" of ptygmatically folded dykes suggests that the process of hydraulic fracturing and sandstone intrusion initiated between burial depths of 40 to 400 m below seabed.
Subsections:Sedimentary petrology
Subjects:Cenozoic; Clastic rocks; Cores; Eocene; Geophysical methods; Geophysical surveys; Hydraulic fracturing; Oil and gas fields; Paleogene; Pore pressure; Reservoir properties; Reservoir rocks; Sandstone; Sedimentary rocks; Sedimentary structures; Seismic methods; Surveys; Tertiary; Veins; Atlantic Ocean; Europe; Great Britain; Moray Firth; North Atlantic; North Sea; Scotland; United Kingdom; Western Europe; Alba Field; Alba Sandstone; Outer Moray Firth
Coordinates:N580000 N580000 E0011200 E0011200
Abstract Numbers:02M/4686
Record ID:2002049567
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from The Geological Society, London, London, United Kingdom
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