New method for measuring compressibility and poroelasticity coefficients in porous and permeable rocks

Pimienta, Lucas Xan; Fortin, Jérôme; Guéguen, Yves

doi:10.1002/2016jb013791

Cited by 38 publications

(22 citation statements)

References 37 publications

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“…The details of this calculation are given in the supporting information. It might also be possible to estimate the solid bulk modulus from forced confining and pore fluid pressure oscillation measurements (Pimienta et al, ). However, for nanoporous media this may be problematic.…”

Section: Methodsmentioning

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: Methodsmentioning

confidence: 99%

Gassmann Theory Applies to Nanoporous Media

Gor

Gurevich

2018

Geophysical Research Letters

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“…Samples from this rock have porosities ranging from 17% to 23% and a quartz content ranging from 75% to 95% (Pimienta et al, ). Bentheim sandstone is a quartz‐rich sandstone also used as a reference rock (e.g., Blöcher et al, ; Louis et al, ; Klein et al, ; Pimienta et al, ; Vajdova et al, ), with a porosity is in the range of 20% up to 25%. All three rock samples are documented to be isotropic and homogeneous at the sample scale, thus allowing for a good applicability of the method tested in this contribution.…”

Section: Experimental Setup and Rock Samplesmentioning

confidence: 99%

Elastic Dispersion and Attenuation in Fully Saturated Sandstones: Role of Mineral Content, Porosity, and Pressures

et al. 2017

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Because measuring the frequency dependence of elastic properties in the laboratory is a technical challenge, not enough experimental data exist to test the existing theories. We report measurements of three fluid‐saturated sandstones over a broad frequency band: Wilkenson, Berea, and Bentheim sandstones. Those sandstones samples, chosen for their variable porosities and mineral content, are saturated by fluids of varying viscosities. The samples elastic response (Young's modulus and Poisson's ratio) and hydraulic response (fluid flow out of the sample) are measured as a function of frequency. Large dispersion and attenuation phenomena are observed over the investigated frequency range. For all samples, the variation at lowest frequency relates to a large fluid flow directly measured out of the rock samples. These are the cause (i.e., fluid flow) and consequence (i.e., dispersion/attenuation) of the transition between drained and undrained regimes. Consistently, the characteristic frequency correlates with permeability for each sandstone. Beyond this frequency, a second variation is observed for all samples, but the rocks behave differently. For Berea sandstone, an onset of dispersion/attenuation is expected from both Young's modulus and Poisson's ratio at highest frequency. For Bentheim and Wilkenson sandstones, however, only Young's modulus shows dispersion/attenuation phenomena. For Wilkenson sandstone, the viscoelastic‐like dispersion/attenuation response is interpreted as squirt flow. For Bentheim sandstone, the second effect does not fully follow such response, which could be due to a lower accuracy in the measured attenuation or to the occurence of another physical effect in this rock sample.

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“…Moreover, for a clean sandstone such as Bentheimer, K s and K s were not only different but also considerably lower than the bulk modulus of quartz. Pimienta et al [22] also indirectly estimated K s for Bentheimer sandstone from measurements of various poroelastic parameters. They observed that K s can be considered as a constant and equal to the bulk modulus of quartz at P > 5.0 MPa.…”

Section: Introductionmentioning

confidence: 99%

Direct measurement of the unjacketed pore modulus of porous solids

2018

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Pressure decline caused by the extraction of oil from deep sedimentary layers depends on the pore modulus K pp , a poroelastic parameter that characterizes the effect of pressure change on pore volume under constant mean stress. Measurement of K pp is difficult, however, as it requires calibration to account for fluid compressibility and compliance of the testing system. Nevertheless, knowing the easily measurable drained pore modulus K p and adopting an assumption on the unjacketed pore modulus K s , it is possible to determine K pp because these pore moduli are related. Previous work on indirectly estimating K s claimed that K s is strongly dependent on Terzaghi effective pressure P and therefore not a constant; also, K s might be different from K s , the solid bulk modulus of the major mineral constituent. We overcome the limitations of the indirect approach by directly measuring K s . The experiments reveal that K s is indeed a constant and that for an ideal porous rock, the assumption of K s = K s holds. Furthermore, a constant K s implies that K p and K pp are functions of Terzaghi effective pressure only. These results provide a framework to accurately determine the Skempton coefficient B.

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New method for measuring compressibility and poroelasticity coefficients in porous and permeable rocks

Cited by 38 publications

References 37 publications

Gassmann Theory Applies to Nanoporous Media

Gassmann Theory Applies to Nanoporous Media

Elastic Dispersion and Attenuation in Fully Saturated Sandstones: Role of Mineral Content, Porosity, and Pressures

Direct measurement of the unjacketed pore modulus of porous solids

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