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Modelling and validation of dry and saturated velocities in carbonates from Saudi Arabia – Part II.
- Source :
-
Journal of Applied Geophysics . Jul2023, Vol. 214, pN.PAG-N.PAG. 1p. - Publication Year :
- 2023
-
Abstract
- Ultrasonic compressional (P -wave) and shear (S -wave) velocity data, obtained from a set of 35 dry and water-saturated (carbonate) core samples, were presented as a first part to this study, in a separate paper by Bakhorji and Schmitt (2022). These carbonate samples were obtained from a prominent reservoir in Saudi Arabia. In this follow-up paper, the velocity measurements, obtained from these 35 core samples, were utilized to, firstly, predict and validate four appropriate rock physics models and to, secondly, derive empirical relationships relating the P - and S -wave velocities to the porosity and calcite content of the samples (over the effective pressure range from 5 MPa to 25 MPa). The derived empirical relationships were validated against the wireline P - and S -wave velocities assuming insitu reservoir pressure conditions. The empirical models predicted the P - and S -wave velocities accurately over the reservoir interval of interest. The shear strengthening / weakening effect, or the saturation effect on the shear moduli, was also modelled and is discussed further. The comparisons of the Biot, Gassmann, Mavko-Jizba-Biot (MJ-Biot) and Mavko-Jizba-Gassmann (MJ-Gassmann) model predictions, with the measured water-saturated P - and S -wave velocities, show that the squirt mechanism was not applicable for our samples. The Gassmann model consistently over-predicts the water-saturated S -wave velocities at low pressure, but closely fits the measured velocities at high pressures, whereas Biot over-predicts the water-saturated velocities in most of the studied samples. We conclude that Biot global-flow is most likely to be the principle dispersion mechanism in these samples. • Validated the applicability of Gassmann and Biot's high-frequency models in Carbonate. • Derived empirical models relating velocities to the porosity and calcite content. • The derived empirical models accurately predicted the velocities. • Verify the flow mechanism affecting the ultrasonic measurements on the samples. • It appeared that Biot global flow was occurring in these samples. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 09269851
- Volume :
- 214
- Database :
- Academic Search Index
- Journal :
- Journal of Applied Geophysics
- Publication Type :
- Academic Journal
- Accession number :
- 164247902
- Full Text :
- https://doi.org/10.1016/j.jappgeo.2023.105066