气候变化领域集成服务门户(CCPortal): Resolution limits of fluid overpressures from mineralogy; porosity; and sonic velocity variations in North Sea mudrocks

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DOI	10.1306/02251917057
	Resolution limits of fluid overpressures from mineralogy; porosity; and sonic velocity variations in North Sea mudrocks
	Hermanrud C.; Hermanrud C.; Undertun O.
发表日期	2019
ISSN	0149-1423
起始页码	2665
结束页码	2695
卷号	103 期号:11
英文摘要	Pore pressure identification in mudrocks largely relies on indirect methods, including analyses of sonic velocity data. The magnitude of pore pressure changes that can be resolved from such data depends on the impact of fluid pressures on well log responses and on the velocity responses to lithological variations that could be mistaken for indications of pore pressure changes. Analysis of relationships between sonic velocity, mineralogy, and porosity from 11 North Sea wells demonstrated porosity variations of up to 5% from the mean value in mudrocks at any given depth between 1 and 3.5 km (3300-11,500 ft). Comparisons of these wells with seven wells from the Norwegian Sea demonstrated that the sonic velocity and density variations are influenced by the content of silica with a biogenic origin, but that they can otherwise not, in general, be related to mineralogy and pore pressure variations. The sonic velocity deviations from the mean value are of the same magnitude as those that would be caused by porosity changes of-8% in mudrocks of uniform lithology. Furthermore, the deviations are not significantly reduced when the velocity data are compensated for changes in density (porosity). Detection limits for mechanically compacting mudrocks that are at their maximum effective stress are equivalent to static mud density changes of 0.1-0.15 g/cm3. These numbers apply to mudrocks with similar lithological variability to those analyzed in our data set but should be much higher when significant amounts of silica with a biogenic origin are present. © 2019 The American Association of Petroleum Geologists. All rights reserved.
语种	英语
scopus关键词	Lithology; Minerals; Pore pressure; Porosity; Silica; Underwater mineralogy; Well logging; Density variations; Lithological variability; Porosity changes; Porosity variations; Pressure identification; Pressure variations; Resolution limits; Velocity response; Velocity; compaction; detection method; effective stress; fluid pressure; lithology; mineralogy; mudstone; overpressure; pore pressure; porosity; sonic boom; well logging; Arctic Ocean; Atlantic Ocean; North Sea; Norwegian Sea
来源期刊	AAPG Bulletin
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/143749
作者单位	Equinor ASA, Stavanger, Norway; Department of Geological Sciences, University of Bergen, Bergen, Norway
推荐引用方式 GB/T 7714	Hermanrud C.,Hermanrud C.,Undertun O.. Resolution limits of fluid overpressures from mineralogy; porosity; and sonic velocity variations in North Sea mudrocks[J],2019,103(11).
APA	Hermanrud C.,Hermanrud C.,&Undertun O..(2019).Resolution limits of fluid overpressures from mineralogy; porosity; and sonic velocity variations in North Sea mudrocks.AAPG Bulletin,103(11).
MLA	Hermanrud C.,et al."Resolution limits of fluid overpressures from mineralogy; porosity; and sonic velocity variations in North Sea mudrocks".AAPG Bulletin 103.11(2019).