Accuracy of Krief, Nur and Pride models in the study of rock physics

Zhang, Jiajia; Li, Hongbing; Liu, Huaishan; Cui, Xingfu

doi:10.1190/1.3255250

Cited by 5 publications

(3 citation statements)

References 18 publications

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“…This method has high accuracy, but is generally difficult to obtain the values expected. (2) Make prediction by the empirical relationship [2−3] or effective medium theory [8−10,12−13] , their prediction accuracy depends on the model assumptions [12,21] .…”

Section: Analytical Formulae Of Elastic Moduli Of Dry Rockmentioning

confidence: 99%

“…According to Eqs. (5)- (8), the critical porosity model implicitly assumes a constant modulus ratio of dry rock, irrespective of porosity, i.e., the ratio of P-wave to S-wave velocity V p /V s of dry rock is equal to the velocity ratio of matrix, but this assumption sometimes does not match with laboratory measurements [4][5]21] . Whereas the Pride model implicitly assumes that the modulus ratio of dry rock increases monotonically with the porosity because the consolidation coefficient is always positive.…”

Section: Analytical Formulae Of Elastic Moduli Of Dry Rockmentioning

confidence: 99%

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Inversion of Effective Pore Aspect Ratios for Porous Rocks and Its Applications

Zhang

Yao

2013

Chinese J of Geophysics

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By integrating Gassmann equations with the dry rock frame model, which is called the DEM analytical model, derived from the differential effective medium theory, this paper presents a method for pore structure evaluation and shear wave velocity prediction from the effective pore aspect ratios inverted from P‐wave (and S‐wave) velocity. First, we build a link among P‐wave and S‐wave velocity, density, porosity, saturation and mineral compositions through Gassmann equations and the DEM analytical model. Then, by assuming that the porous rock contains spheroidal pores with a single aspect ratio, we apply nonlinear global optimization algorithm to find the best estimate for the effective pore aspect ratio in terms of minimizing the error between theoretical predictions and experimental measurements. Finally, we estimate the S‐wave velocity from the inverted effective pore aspect ratios. The experimental and well logging examples show that the inverted aspect ratio can be used to accurately indicate the pore structure of the reservoir. For fracture reservoirs, such as granite, its pore aspect ratio is typically less than 0.025, and for pore reservoirs such as sandstone, the pore aspect ratio is usually greater than 0.08. Comparison of the inversion of pore aspect ratio between only from P‐wave and from both P‐wave and S‐wave indicates that the pore aspect ratios from these two methods are almost the same. And, the predicted shear‐velocity only from P‐wave is in good agreement with the measured one. These results show that our method of the shear‐velocity prediction by using the pore aspect ratio inverted from P‐wave is effective.

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Section: Analytical Formulae Of Elastic Moduli Of Dry Rockmentioning

confidence: 99%

Section: Analytical Formulae Of Elastic Moduli Of Dry Rockmentioning

confidence: 99%

Inversion of Effective Pore Aspect Ratios for Porous Rocks and Its Applications

Zhang

Yao

2013

Chinese J of Geophysics

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“…Lee (2006) generalized and modified Pride's formula for shear modulus. Zhang, Li, Liu and Cui (2009) applied Krief, Nur and Pride models to Gassmann equations (Gassmann 1951) and checked their accuracy and applicability.…”

Section: Introductionmentioning

confidence: 99%

Rock physics modelling of porous rocks with multiple pore types: a multiple‐porosity variable critical porosity model

Zhang

Yingyao

Zhang

2019

Geophysical Prospecting

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A B S T R A C TA critical porosity model establishes the empirical relationship between a grain matrix and a dry rock by the concept of critical porosity. The model is simple and practical and widely used. But the critical porosity in the model is a fixed value that cannot relate to pore structure. The aim of this paper is to establish the theoretical relationship between critical porosity and pore structure by combining Kuster-Toksöz theory with the critical porosity model. Different from the traditional critical porosity model, critical porosity is not an empirical value but varied with pore shape and the ratio of bulk modulus versus shear modulus of the grain matrix. The substitution of the theoretical relationship into Kuster-Toksöz theory will generate the formulae for the bulk and shear moduli of multiple-porosity dry rocks, which is named the multipleporosity variable critical porosity model. The new model has been used to predict elastic moduli for sandstone and carbonate rock. We compare the modelling results for P-and S-wave velocities and elastic moduli with the experimental data. The comparison shows that the new model can be used to describe the elastic properties for the rocks with multiple pore types.

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Rock critical porosity inversion and S-wave velocity prediction

Zhang

Yao

2012

Appl. Geophys.

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Accuracy of Krief, Nur and Pride models in the study of rock physics

Cited by 5 publications

References 18 publications

Inversion of Effective Pore Aspect Ratios for Porous Rocks and Its Applications

Inversion of Effective Pore Aspect Ratios for Porous Rocks and Its Applications

Rock physics modelling of porous rocks with multiple pore types: a multiple‐porosity variable critical porosity model

Rock critical porosity inversion and S-wave velocity prediction

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