Rock Physics Analysis of Shale Reservoirs

Pervikhina, Marina; Gurevich, Boris; Dewhurst, David N.; Golodoniuc, Pavel; Lebedev, Maxim

doi:10.1002/9781119039228.ch9

Cited by 4 publications

(2 citation statements)

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“…Application of geophysical methods to unconventional reservoirs requires thorough understanding of physical properties of these formations. While there have been significant advances in both experimental and theoretical rock physics of unconventional reservoirs (e.g., recent review by Pervukhina et al, ), some fundamental questions are still poorly understood. In particular, it is not known whether the Gassmann theory, which plays a central role in seismic characterization of conventional reservoirs (Smith et al, ), applies to nanoporous materials (Following the most recent IUPAC convention we call here “nanoporous materials,” those materials that have the pore sizes below 100 nm; Thommes et al, ).…”

Section: Introductionmentioning

confidence: 99%

Gassmann Theory Applies to Nanoporous Media

Gor

Gurevich

2018

Geophysical Research Letters

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Recent progress in extraction of unconventional hydrocarbon resources has ignited the interest in the studies of nanoporous media. Since many thermodynamic and mechanical properties of nanoscale solids and fluids differ from the analogous bulk materials, it is not obvious whether wave propagation in nanoporous media can be described using the same framework as in macroporous media. Here we test the validity of Gassmann equation using two published sets of ultrasonic measurements for a model nanoporous medium, Vycor glass, saturated with two different fluids, argon, and n‐hexane. Predictions of the Gassmann theory depend on the bulk and shear moduli of the dry samples, which are known from ultrasonic measurements and the bulk moduli of the solid and fluid constituents. The solid bulk modulus can be estimated from adsorption‐induced deformation or from elastic effective medium theory. The fluid modulus can be calculated according to the Tait‐Murnaghan equation at the solvation pressure in the pore. Substitution of these parameters into the Gassmann equation provides predictions consistent with measured data. Our findings set up a theoretical framework for investigation of fluid‐saturated nanoporous media using ultrasonic elastic wave propagation.

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Section: Introductionmentioning

confidence: 99%

Gassmann Theory Applies to Nanoporous Media

Gor

Gurevich

2018

Geophysical Research Letters

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“…However, the method allows estimating baseline properties of organic‐lean shales. The properties of organic‐rich shales can be then obtained using a number of effective medium methods (e.g., Pervukhina et al., 2015b; Sayers, 2013).…”

Section: Discussionmentioning

confidence: 99%

Modeling of Compaction Trends of Anisotropic Elastic Properties of Shales

et al. 2021

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Knowledge of anisotropic elastic properties of shales is important for understanding of shale compaction trends, improved seismic to well tie, nonhyperbolic moveout correction as well as for establishing a baseline for predicting properties of organic-rich shales. So far, however, building a predictive model of elastic properties of shales remains a difficult task. This might be explained by the multiparametric character of such modeling and the fact that the effects of some parameters cannot be measured and are thus poorly understood. The significant number of parameters required for prediction of the elastic properties of shale stems from its multicomponent nature. Shales are nanocomposite materials that comprise phyllosilicate clay particles with a substantial part of their grain size distribution smaller than 2 μm in radius and typically silt particles of quartz and feldspar with grain sizes between 2 and 60 μm (Mitchell & Soga, 2005). The complexity of the system is complemented by pores of micrometer to nanometer scale, whose shape and orientation are seldom characterized (Desbois, 2009). In the smallest of these pores, the filling water contributes to the stiffness and rigidity of the composite via electrostatic and van der Waals interactions (Holt & Kolsto, 2017). Attempts to model elastic properties of shales began with the classic work of Hornby et al. (1994) who modeled shale as a composite material that comprises anisotropic water-saturated clay blocks with a preferred orientation, silt inclusions, and free water. The orientation distribution function (ODF) of the clay crystals was estimated from scanning electron microscopy and the silt fraction from X-ray diffraction analysis or microtomographic images. The other unknown parameters, namely, elastic moduli of the clay blocks, aspect ratio of pores, and the fractions of free water and bound water in the clay blocks became fitting parameters.

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