Frequency dependence of anisotropy in fluid saturated rocks – Part I: aligned cracks case
A major cause of attenuation in fluid-saturated media is the local fluid flow (or squirt flow) induced by a passing wave between pores of different shapes and sizes. Several squirt flow models have been derived for isotropic media. For anisotropic media however, most of the existing squirt flow mode...
| Main Authors: | , |
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| Format: | Journal Article |
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Wiley-Blackwell
2016
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| Online Access: | http://hdl.handle.net/20.500.11937/10340 |
| _version_ | 1848746206204788736 |
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| author | Collet, O. Gurevich, Boris |
| author_facet | Collet, O. Gurevich, Boris |
| author_sort | Collet, O. |
| building | Curtin Institutional Repository |
| collection | Online Access |
| description | A major cause of attenuation in fluid-saturated media is the local fluid flow (or squirt flow) induced by a passing wave between pores of different shapes and sizes. Several squirt flow models have been derived for isotropic media. For anisotropic media however, most of the existing squirt flow models only provide the low- and high-frequency limits of the saturated elastic properties. We develop a new squirt flow model to account for the frequency dependence of elastic properties and thus gain some insight into velocity dispersion and attenuation in anisotropic media. In this paper, we focus on media containing aligned compliant pores embedded in an isotropic background matrix. The low- and high-frequency limits of the predicted fluid-saturated elastic properties are respectively consistent with Gassmann theory and Mukerji–Mavko squirt flow model. Results are also expressed in terms of Thomsen anisotropy parameters. It turns out that the P-wave anisotropy parameter ε tends to zero in the high-frequency limit, whereas the δ parameter remains the only indicator of P-S⊥ anisotropy. The S-wave anisotropy parameter γ is not affected by the presence of fluid and remains the same for all frequency ranges. A new definition for attenuation anisotropy parameters is also proposed to quantify the attenuation anisotropy. In the most important case of liquid saturation, analytical expressions are derived for elastic properties, velocity anisotropy parameters, quality factors, and attenuation anisotropy parameters. A companion paper considers the case of cracks with an ellipsoidal distribution of orientations resulting from the application of anisotropic stress. |
| first_indexed | 2025-11-14T06:29:34Z |
| format | Journal Article |
| id | curtin-20.500.11937-10340 |
| institution | Curtin University Malaysia |
| institution_category | Local University |
| last_indexed | 2025-11-14T06:29:34Z |
| publishDate | 2016 |
| publisher | Wiley-Blackwell |
| recordtype | eprints |
| repository_type | Digital Repository |
| spelling | curtin-20.500.11937-103402017-09-13T14:52:45Z Frequency dependence of anisotropy in fluid saturated rocks – Part I: aligned cracks case Collet, O. Gurevich, Boris A major cause of attenuation in fluid-saturated media is the local fluid flow (or squirt flow) induced by a passing wave between pores of different shapes and sizes. Several squirt flow models have been derived for isotropic media. For anisotropic media however, most of the existing squirt flow models only provide the low- and high-frequency limits of the saturated elastic properties. We develop a new squirt flow model to account for the frequency dependence of elastic properties and thus gain some insight into velocity dispersion and attenuation in anisotropic media. In this paper, we focus on media containing aligned compliant pores embedded in an isotropic background matrix. The low- and high-frequency limits of the predicted fluid-saturated elastic properties are respectively consistent with Gassmann theory and Mukerji–Mavko squirt flow model. Results are also expressed in terms of Thomsen anisotropy parameters. It turns out that the P-wave anisotropy parameter ε tends to zero in the high-frequency limit, whereas the δ parameter remains the only indicator of P-S⊥ anisotropy. The S-wave anisotropy parameter γ is not affected by the presence of fluid and remains the same for all frequency ranges. A new definition for attenuation anisotropy parameters is also proposed to quantify the attenuation anisotropy. In the most important case of liquid saturation, analytical expressions are derived for elastic properties, velocity anisotropy parameters, quality factors, and attenuation anisotropy parameters. A companion paper considers the case of cracks with an ellipsoidal distribution of orientations resulting from the application of anisotropic stress. 2016 Journal Article http://hdl.handle.net/20.500.11937/10340 10.1111/1365-2478.12384 Wiley-Blackwell restricted |
| spellingShingle | Collet, O. Gurevich, Boris Frequency dependence of anisotropy in fluid saturated rocks – Part I: aligned cracks case |
| title | Frequency dependence of anisotropy in fluid saturated rocks – Part I: aligned cracks case |
| title_full | Frequency dependence of anisotropy in fluid saturated rocks – Part I: aligned cracks case |
| title_fullStr | Frequency dependence of anisotropy in fluid saturated rocks – Part I: aligned cracks case |
| title_full_unstemmed | Frequency dependence of anisotropy in fluid saturated rocks – Part I: aligned cracks case |
| title_short | Frequency dependence of anisotropy in fluid saturated rocks – Part I: aligned cracks case |
| title_sort | frequency dependence of anisotropy in fluid saturated rocks – part i: aligned cracks case |
| url | http://hdl.handle.net/20.500.11937/10340 |