Pore networks in continental and marine mudstones; characteristics and controls on sealing behavior

Mudstone pore networks are strong modifiers of sedimentary basin fluid dynamics and have a critical role in the distribution of hydrocarbons and containment of injected fluids. Using core samples from continental and marine mudstones, we investigate properties of pore types and networks from a varie...

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Bibliographic Details
Published in:Geosphere (Boulder, Colo.) Colo.), 2011-04, Vol.7 (2), p.429-454
Main Authors: Heath, Jason E, Dewers, Thomas A, McPherson, Brian J. O. L, Petrusak, Robin, Chidsey, Jr, Rinehart, Alex J, Mozley, Peter S
Format: Article
Language:English
Subjects:
cap rocks
Carboniferous
case studies
clastic rocks
Cretaceous
Gothic Shale
Gulf Coastal Plain
histograms
image analysis
imagery
Kirtland Shale
Mesozoic
Mississippi
mudstone
New Mexico
Paleozoic
Paradox Formation
Pennsylvanian
permeability
porosity
properties
San Juan Basin
sealing
sed rocks, sediments
Sedimentary petrology
sedimentary rocks
SEM data
Southwestern U.S
statistical analysis
thin sections
United States
Upper Cretaceous
Utah
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Summary:Mudstone pore networks are strong modifiers of sedimentary basin fluid dynamics and have a critical role in the distribution of hydrocarbons and containment of injected fluids. Using core samples from continental and marine mudstones, we investigate properties of pore types and networks from a variety of geologic environments, together with estimates of capillary breakthrough pressures by mercury intrusion porosimetry. Analysis and interpretation of quantitative and qualitative three-dimensional (3D) observations, obtained by dual focused ion beam-scanning electron microscopy, suggest seven dominant mudstone pore types distinguished by geometry and connectivity. A dominant planar pore type occurs in all investigated mudstones and generally has high coordination numbers (i.e., number of neighboring connected pores). Connected networks of pores of this type contribute to high mercury capillary pressures due to small pore throats at the junctions of connected pores and likely control most matrix transport in these mudstones. Other pore types are related to authigenic (e.g., replacement or pore-lining precipitation) clay minerals and pyrite nodules; pores in clay packets adjacent to larger, more competent clastic grains; pores in organic phases; and stylolitic and microfracture-related pores. Pores within regions of authigenic clay minerals often form small isolated networks (
ISSN:1553-040X
1553-040X
DOI:10.1130/GES00619.1