Pressure cells and pressure seals in the UK Central Graben

被引:63
作者
Darby, D [1 ]
Haszeldine, RS [1 ]
Couples, GD [1 ]
机构
[1] UNIV GLASGOW,DEPT GEOL & APPL GEOL,GLASGOW G12 8QQ,LANARK,SCOTLAND
基金
英国自然环境研究理事会;
关键词
overpressure; pressure seals; North Sea;
D O I
10.1016/S0264-8172(96)00023-2
中图分类号
P [天文学、地球科学];
学科分类号
07 ;
摘要
The Central Graben of the North Sea is characterised by high levels of overpressure (up to 40 MPa overpressure at 4500 m depth). We present pressure data for Cenozoic and Mesozoic reservoirs. Palaeocene sandstones control pressures in Tertiary mudstones and Cretaceous Chalk by acting as a regional 'drain'. We divide the Jurassic into 18 pressure cells. The rift structure of the Graben controls the magnitude of pressure in each cell. Lateral hydraulic communication exists over 10 km distance between deeply-buried terraces (> 5000 m depth) and shallow structural highs (< 4500 m depth). Lateral communication increases pressure in the structurally-elevated sandstones to the minimum stress. This dynamic process produces zones of vertical fluid flow on the Forties-Montrose High, termed Leak Points. Vertical flow at Leak Points produces a 20 MWm(-2) heat flow anomaly and controls hydrocarbon retention. Leak Points are water-wet, while deep terraces in hydraulic communication with Leak Points are condensate-bearing. The Kimmeridge Clay Fm. forms the pressure seal in deep terraces. Copyright (C) 1996 Elsevier Science Ltd
引用
收藏
页码:865 / 878
页数:14
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