Quartz diagenesis and convective fluid movement; Beatrice Oilfield, UK North Sea

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Authors:Haszeldine, R. S.; Samson, Iain M.; Cornford, C.
Author Affiliations:Primary:
Britoil, Stratigr. Lab., Glasgow, United Kingdom
Univ. London, Queen Mary Coll., Dep. Geol. Sci., United Kingdom
Strathclyde Univ., Dep. Appl. Geol., United Kingdom
Volume Title:Patterns of mineral diagenesis on the NW European continental shelf and their relations to facies and hydrocarbon accumulation
Volume Authors:Morgan, D. J., editor; Rawson, P. F.
Source:Clay Minerals, 19(3), p.391-402; Joint meeting of the Clay Minerals Group of the Mineralogical Society and the Petroleum Exploration Society of Great Britain ; Patterns of mineral diagenesis on the NW European continental shelf and their relations to facies and hydrocarbon accumulation, Cambridge, United Kingdom, April 7-8, 1984, edited by D. J. Morgan and P. F. Rawson. Publisher: Mineralogical Society, London, United Kingdom. ISSN: 0009-8558
Publication Date:1984
Note:In English. 18 refs.; illus. incl. sketch map
Summary:The extent of diagenesis in Lower Jurassic shoreline sandstones of the Beatrice oilfield was controlled primarily by their detrital clay content. Sandstones rich in detrital clay had low depositional permeabilities; these show preservation of detrital feldspars to the present day and have no extensive diagenetic quartz overgrowths. Sandstones poor in detrital clay had high permeabilities and show large quartz overgrowths as part of a normal sub-arkosic diagenetic sequence. Such quartz occurs preferentially below, but not above, impermeable mudstones. These low- and high-permeability features suggest that pore-fluid flow was important during diagenesis. Fluid inclusions trapped in diagenetic quartz overgrowths formed between 68° and 94°C. This silica was probably supplied in solution from the temperature-driven illitization of smectitic clays surrounding these sandstones deeper in the basin. Fluid volumes from clay dewatering, from mechanical compaction, or from influx of overlying seawater were too small to transport diagenetic silica volumes. Silica-rich fluids were probably transported up-dip by convective cells within the sandstones and authigenic quartz precipitated as these fluids cooled. This episode of quartz diagenesis could have been completed within 1·6 × 106 yr if fluid velocities were 3·1 m/yr. Similar convective fluid flows could have transported the fluids responsible for secondary porosity development and the hydrocarbons expelled from mudstones later in the basin burial history. [D.J.M.]
Subjects:Authigenic minerals; Clastic rocks; Diagenesis; Fluid inclusions; Framework silicates; Geologic thermometry; Inclusions; Jurassic; Lower Jurassic; Materials; Mesozoic; Migration; Models; Mudstone; Overgrowths; Permeability; Petroleum; Pore water; Porosity; Quartz; Sandstone; Secondary porosity; Sedimentary petrology; Sedimentary rocks; Silica minerals; Silicates; Solution; Temperature; Atlantic Ocean; Europe; North Atlantic; North Sea; United Kingdom; Western Europe; Beatrice oil field; Evolution; Firth Basin
Coordinates:N580000 N581500 W0030000 W0031500
Abstract Numbers:85M/2024
Record ID:1985033739
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Abstract, Copyright, Mineralogical Society of Great Britain and Ireland
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