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TitleContinuous porosity characterization: metric-scale intervals in heterogeneous sedimentary rocks using medical CT-scanner
AuthorLarmagnat, S; Des Roches, M; Daigle, L -F; Francus, P; Lavoie, DORCID logo; Raymond, J; Malo, M; Aubiès-Trouilh, A
SourceMarine and Petroleum Geology vol. 109, 2019 p. 361-380, Open Access logo Open Access
Alt SeriesNatural Resources Canada, Contribution Series 20190055
PublisherElsevier BV
Mediapaper; on-line; digital
File formatpdf (Adobe® Reader®); html
Subjectsfossil fuels; geophysics; Science and Technology; petroleum resources; hydrocarbons; reservoir rocks; bedrock geology; lithology; sedimentary rocks; porosity; pore structure; pore geometry; core samples; core analysis; sample preparation; Methodology
Illustrationsdiagrams; geophysical images; tables; photomicrographs; lithologic sections; profiles; location maps; geoscientific sketch maps; photographs; schematic diagrams; flow diagrams; graphs; plots
ProgramEnvironmental Geoscience Management
Released2019 05 13
AbstractAlthough computed tomography (CT-Scanning) has been regularly applied to core analyses in petroleum geology, there is still a need to improve our ways to document porosity and porosity distribution in the entire pore scale spectrum, from the tens of nanometer to the meter-scale. Porosity imaging is particularly crucial for complex and heterogeneous rocks such as hydrothermally altered and fractured carbonates. The present work proposes an improved method using medical-CT to reliably estimate reservoir porosity. An in-house core-flooding setup allowed to analyse several individual core samples, scanned simultaneously (dry and saturated), as well as continuous core sections up to 1.5m long. Without any prior knowledge of samples, three-dimensional alignment and subtraction of the two data sets (dry and saturated states) results in the generation of 3D porosity matrices. The methodology tested on a large set of reference core material shows a strong correlation between conventional gas porosimetry techniques and porosity from CT-scan. The added value of the porosity measurements by CT-scan is, first of all, the generation of 3D images of pore network, allowing to assess spatial attributes of macropores, their distribution and connectivity. Secondly, the CT-scan method also provides continuous porosity profile at the millimetric scale. Both developments are crucial for the understanding of reservoir rock properties.
Summary(Plain Language Summary, not published)
An improved methodology combining a core-flooding setup and medical-CT analyses to obtain the porosity of heterogeneous rock material was defined. The methodology has been tested on reference core material that has a wide range of porosity values and includes seven different sedimentary rocks. The enhanced CT methodology has proven to be as valuable as conventional ways to determine porosity in rock material (i.e. helium gas porosimetry). 3D porosity matrices can be additionally generated to visualize the connected porosity network to produce a reliable estimate of the average porosity value for each sample. Another major add-on is the production of continuous porosity profiles at the millimetric scale. Such developments have potential to improve our understanding of heterogeneous rock materials in a wide range of disciplines, from oil and gas industry, geothermal resources or hydrogeology.

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