Viscoelasticity of precompacted unconsolidated sand with viscous cement

Leurer, Klaus C.; Dvorkin, Jack

doi:10.1190/1.2187795

Cited by 25 publications

(14 citation statements)

References 18 publications

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“…() showed that the presence of pores with a low aspect ratio leads to a dramatic increase of the difference between effective shear moduli of the dry and solid saturated rock, an effect similar to the stiffening effect of squirt flow in fluid‐filled rocks at ultrasonic frequencies. This similarity was recognized by Leurer and Dvorkin () who proposed the term ‘solid squirt’ to describe the stiffening of the compliant grain contacts by a solid infill. More generally, the works of Leurer and Dvorkin () and Makarynska et al .…”

Section: Introductionmentioning

confidence: 70%

A triple porosity scheme for fluid/solid substitution: theory and experiment

Sun

Gurevich

Lebedev

et al. 2018

Geophysical Prospecting

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Quantifying the effects of pore‐filling materials on elastic properties of porous rocks is of considerable interest in geophysical practice. For rocks saturated with fluids, the Gassmann equation is proved effective in estimating the exact change in seismic velocity or rock moduli upon the changes in properties of pore infill. For solid substance or viscoelastic materials, however, the Gassmann theory is not applicable as the rigidity of the pore fill (either elastic or viscoelastic) prevents pressure communication in the pore space, which is a key assumption of the Gassmann equation. In this paper, we explored the elastic properties of a sandstone sample saturated with fluid and solid substance under different confining pressures. This sandstone sample is saturated with octadecane, which is a hydrocarbon with a melting point of 28°C, making it convenient to use in the lab in both solid and fluid forms. Ultrasonically measured velocities of the dry rock exhibit strong pressure dependency, which is largely reduced for the filling of solid octadecane. Predictions by the Gassmann theory for the elastic moduli of the sandstone saturated with liquid octadecane are consistent with ultrasonic measurements, but underestimate the elastic moduli of the sandstone saturated with solid octadecane. Our analysis shows that the difference between the elastic moduli of the dry and solid‐octadecane‐saturated sandstone is controlled by the squirt flow between stiff, compliant, and the so‐called intermediate pores (with an aspect ratio larger than that of compliant pore but much less than that of stiff pores). Therefore, we developed a triple porosity model to quantify the combined squirt flow effects of compliant and intermediate pores saturated with solid or viscoelastic infill. Full saturation of remaining stiff pores with solid or viscoelastic materials is then considered by the lower embedded bound theory. The proposed model gave a reasonable fit to the ultrasonic measurements of the elastic moduli of the sandstone saturated with liquid or solid octadecane. Comparison of the predictions by the new model to other solid substitution schemes implied that accounting for the combined effects of compliant and intermediate pores is necessary to explain the solid squirt effects.

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Section: Introductionmentioning

confidence: 70%

A triple porosity scheme for fluid/solid substitution: theory and experiment

Sun

Gurevich

Lebedev

et al. 2018

Geophysical Prospecting

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“…Rather than modifying the BSM, the original Biot formulation is used as the general framework. Two viscoelastic models are included that consist of extended formulations of ͑1͒ an effectivegrain model 15 ͑EGM͒ and ͑2͒ a viscoelastic-contact model 24 ͑VCM͒. Nevertheless, it can still be argued that the model presented here, apart from the EGM, represents a refinement of the BSM, because it was the original idea of introducing an energy-dissipating skeletal frame that made Biot's theory applicable to unconsolidated marine sediment.…”

Section: Introductionmentioning

confidence: 96%

Acoustics of marine sediment under compaction: Binary grain-size model and viscoelastic extension of Biot’s theory

Leurer¹,

Brown²

2008

The Journal of the Acoustical Society of America

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This paper presents a model of acoustic wave propagation in unconsolidated marine sediment, including compaction, using a concept of a simplified sediment structure, modeled as a binary grain-size sphere pack. Compressional- and shear-wave velocities and attenuation follow from a combination of Biot's model, used as the general framework, and two viscoelastic extensions resulting in complex grain and frame moduli, respectively. An effective-grain model accounts for the viscoelasticity arising from local fluid flow in expandable clay minerals in clay-bearing sediments. A viscoelastic-contact model describes local fluid flow at the grain contacts. Porosity, density, and the structural Biot parameters (permeability, pore size, structure factor) as a function of pressure follow from the binary model, so that the remaining input parameters to the acoustic model consist solely of the mass fractions and the known mechanical properties of each constituent (e.g., carbonates, sand, clay, and expandable clay) of the sediment, effective pressure, or depth, and the environmental parameters (water depth, salinity, temperature). Velocity and attenuation as a function of pressure from the model are in good agreement with data on coarse- and fine-grained unconsolidated marine sediments.

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“…The Cole-Cole model describes well the frequency dependencies of velocities and absorptions in the frequency range from units of hertz to hundreds of kilohertz (Batzle et al, 2006;Gurevich et al, 2008;Jones, 1986;. In the works of Leurer and Dvorkin (2000); Leurer and Dvorkin (2006) the Cole-Cole method has been successfully applied for the description of squirt flows in granular geomaterials whose grains are covered with viscous fluid.…”

Section: Introductionmentioning

confidence: 98%