The effect of spatial distribution of clay platelets on the anisotropy of clay in shales

Abstract

PreviousNext No AccessFirst International Meeting for Applied Geoscience & Energy Expanded AbstractsThe effect of spatial distribution of clay platelets on the anisotropy of clay in shalesAuthors: Colin M. SayersLennert D. den BoerColin M. SayersUniversity of HoustonSearch for more papers by this author and Lennert D. den BoerConsultantSearch for more papers by this authorhttps://doi.org/10.1190/segam2021-3581747.1 SectionsSupplemental MaterialAboutPDF/ePub ToolsAdd to favoritesDownload CitationsTrack CitationsPermissions ShareFacebookTwitterLinked InRedditEmail AbstractThe elastic properties of clay in shales can be derived from a simple model consisting of domains of partially aligned anisotropic clay platelets embedded in a softer interplatelet medium representing clay-bound water and interparticle contacts. Approximating clay platelets as ellipsoidal inclusions and the interplatelet medium as isotropic, with effective bulk and shear moduli, allows the effect of the spatial distribution of inclusions upon the elastic properties of the clay matrix to be investigated. The pair distribution function governs the respective locations of clay platelets and is similarly assumed to be ellipsoidal. Due to compaction, the spacing of clay platelets perpendicular to their long axis is typically less than their spacing parallel to it. Hence, the aspect ratio of the pair distribution function is less than that of the clay platelets. This paper examines the impact of the pair distribution function upon the elastic stiffnesses and anisotropy of clay domains. Assuming a lower aspect ratio for the pair distribution function than for the clay platelets is found to reduce in-plane elastic stiffnesses C11, C12 and C66, but to increase out-of-plane stiffnesses C33, C13 and C55. Since in-plane elastic stiffnesses decrease whereas out-of-plane elastic moduli increase as the aspect ratio of the pair distribution function decreases below that of the clay platelets, the anisotropy parameters ε, γ and η decrease. However, the change in Thomsen’s δ parameter is positive.Keywords: anisotropy, mudrocks, rock physics, shale, VTIPermalink: https://doi.org/10.1190/segam2021-3581747.1FiguresReferencesRelatedDetails First International Meeting for Applied Geoscience & Energy Expanded AbstractsISSN (print):1052-3812 ISSN (online):1949-4645Copyright: 2021 Pages: 3561 publication data© 2021 Published in electronic format with permission by the Society of Exploration GeophysicistsPublisher:Society of Exploration Geophysicists HistoryPublished: 01 Sep 2021 CITATION INFORMATION Colin M. Sayers and Lennert D. den Boer, (2021), "The effect of spatial distribution of clay platelets on the anisotropy of clay in shales," SEG Technical Program Expanded Abstracts : 2263-2267. https://doi.org/10.1190/segam2021-3581747.1 Plain-Language Summary Keywordsanisotropymudrocksrock physicsshaleVTIPDF DownloadLoading ...