Influence of pore fluid and frequency on elastic properties of greensand as interpreted using NMR data

Zakir Hossain, Tapan Mukerj, Ida Lykke Fabricius

Research output: Chapter in Book/Report/Conference proceedingArticle in proceedingsResearchpeer-review

Abstract

The objective of this study was to discuss the influence of pore fluid on elastic properties of greensand. Gassmann’s equations generally work at low frequency and do not take into consideration the fluid related dispersion. In some cases Biot’s theory is used to describe the fluid related dispersion. However, Biot’s theory does not fully explain the frequency dispersion of sedimentary rocks. Greensands are composed of a mixture of quartz and micro-porous glauconite grains. In greensand, it is possible that the contrast between flow in macro-pores and micro-pores within glauconites gives rise to a local stiffening pressure gradient in the fluid. Then fluid flow in greensand could then be described as a kind of squirt flow. Greensand data from the North Nini filed was included in this study. Gassmann’s, Biot’s and squirt models were used to discuss the influence of pore fluid on elastic moduli. Biot’s critical frequency and NMR (nuclear magnetic resonance) T2 spectrum were combined to describe the differences in fluid flow within macro-pores and within micro-pores. NMR data show that Biot’s flow should occur only in large pores in the greensand while, Biot’s flow should not occur in micro-pores. Differences of fluid flow in macro-pores and micro-pores pores are described as high frequency squirt flow in greensand.
Original languageEnglish
Title of host publicationSociety of Exploration Geophysicists International Exposition and 81st Annual Meeting
Publication date2011
Pages2177-2182
Publication statusPublished - 2011
EventSociety of Exploration Geophysicists International Exposition and 81st Annual Meeting - Harry B Gonzales Convention Center, San Antonio, United States
Duration: 19 Sep 201123 Sep 2011
Conference number: 81

Conference

ConferenceSociety of Exploration Geophysicists International Exposition and 81st Annual Meeting
Number81
LocationHarry B Gonzales Convention Center
Country/TerritoryUnited States
CitySan Antonio
Period19/09/201123/09/2011

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