Dynamic permeability of porous rocks and its seismic signatures

In inhomogeneous porous media, the mechanism of wave-induced fluid flow causes significant attenuation and dispersion of seismic waves. In connection with this phenomenon, we study the impact of spatial permeability fluctuations on the dynamic behavior of porous materials. This heterogeneous permeability distribution further complicates the ongoing efforts to extract flow permeability from seismic data. Based on the method of statistical smoothing applied to Biot’s equations of poroelasticity, we derive models for the dynamic-equivalent permeability in 1D and 3D randomly inhomogeneous media. The low-frequency limit of this permeability corresponds to the flow permeability governing fluid flow in porous media. We incorporate the dynamic-equivalent permeability model into the expressions for attenuation and dispersion of P-waves, also obtained by the method of smoothing. The resulting attenuation and dispersion model is confirmed by numerical computations in randomly layered poroelastic structures. The results suggest that the effect of wave-induced fluid flow can be observed in a broader frequency range than previously thought. The peak attenuation shifts along the frequency axis depending on the strength of the permeability fluctuations. We conclude that estimation of flow permeability from seismic attenuation is only possible if permeability fluctuations are properly accounted for.

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Experimental Study of Natural Ions and Rock Interactions for Seawater Breakthrough Percentage Monitoring during Offshore Seawater Flooding

SPE Journal ◽

10.2118/201553-pa ◽

2021 ◽

pp. 1-21

Author(s):

Yanqing Wang ◽

Xiang Li ◽

Jun Lu

Keyword(s):

Porous Media ◽

Fluid Flow ◽

Barium Sulfate ◽

Large Deviation ◽

Exchange Process ◽

Reaction Model ◽

Sodium Content ◽

Flow In Porous Media ◽

Formation Water ◽

The Impact

Summary Seawater breakthrough percentage monitoring is critical for offshore oil reservoirs because seawater fraction is an important parameter for estimating the severity of many flow assurance issues caused by seawater injection and further developing effective strategies to mitigate the impact of those issues on production. The validation of using natural ions as a tracer to calculate the seawater fraction was investigated systematically by studying the natural chemical composition evolution in porous media using coreflood tests and static bottle tests. The applicable range of ions was discussed based on the interaction between ion and rock. The barium sulfate reactive model was improved by integrating interaction between ions and rock as well as fluid flow effect. The results indicate that chloride and sodium interact with rock, but the influence of the interaction can be minimized to a negligible level because of the high concentrations of chloride and sodium. Thus, chloride and sodium can be used as conservative tracers during the seawater flooding process. However, adsorption/desorption may have a large influence on chloride and sodium concentrations under the scenario that both injection water and formation water have low chloride and sodium content. Bromide shows negligible interaction with rock even at low concentrations and can be regarded as being conservative. The application of a barium and sulfate reaction model in coreflood tests does not work as well as in bottle tests because fluid flow in porous media and ion interaction with rock is not taken into account. Although sulfate and barium adsorption on clay is small, it should not be neglected. The barium sulfate reaction model was improved based on the simulation of ion transport in porous media. Cations (magnesium, calcium, and potassium) are involved in the complicated cation-exchange process, which causes large deviation. Therefore, magnesium, calcium, and potassium are not recommended to calculate seawater fraction. Boron, which exists as anions in formation water and is used as a conservative tracer, has significant interactions with core matrix, and using boron in an ion tracking method directly can significantly underestimate the seawater fraction. The results give guidelines on selecting suitable ions as tracers to determine seawater breakthrough percentages under different production scenarios.

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The Impact of Pore Size and Pore Connectivity on Single-Phase Fluid Flow in Porous Media

Advanced Engineering Materials ◽

10.1002/adem.201000255 ◽

2010 ◽

Vol 13 (3) ◽

pp. 208-215 ◽

Cited By ~ 14

Author(s):

Zeyun Jiang ◽

Kejian Wu ◽

Gary D. Couples ◽

Jingsheng Ma

Keyword(s):

Porous Media ◽

Fluid Flow ◽

Pore Size ◽

Single Phase ◽

Flow In Porous Media ◽

Pore Connectivity ◽

The Impact ◽

Phase Fluid

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Wave-induced fluid flow in random porous media: Attenuation and dispersion of elastic waves

The Journal of the Acoustical Society of America ◽

10.1121/1.1894792 ◽

2005 ◽

Vol 117 (5) ◽

pp. 2732-2741 ◽

Cited By ~ 82

Author(s):

Tobias M. Müller ◽

Boris Gurevich

Keyword(s):

Porous Media ◽

Fluid Flow ◽

Elastic Waves ◽

Random Porous Media ◽

Wave Induced ◽

Attenuation And Dispersion

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Seismic wave attenuation and dispersion resulting from wave-induced flow in porous rocks — A review

Geophysics ◽

10.1190/1.3463417 ◽

2010 ◽

Vol 75 (5) ◽

pp. 75A147-75A164 ◽

Cited By ~ 457

Author(s):

Tobias M. Müller ◽

Boris Gurevich ◽

Maxim Lebedev

Keyword(s):

Fluid Flow ◽

Velocity Dispersion ◽

Wave Attenuation ◽

Field Measurements ◽

Theoretical Models ◽

Seismic Attenuation ◽

P Wave ◽

Induced Flow ◽

Wave Induced ◽

Attenuation And Dispersion

One major cause of elastic wave attenuation in heterogeneous porous media is wave-induced flow of the pore fluid between heterogeneities of various scales. It is believed that for frequencies below [Formula: see text], the most important cause is the wave-induced flow between mesoscopic inhomogeneities, which are large compared with the typical individual pore size but small compared to the wavelength. Various laboratory experiments in some natural porous materials provide evidence for the presence of centimeter-scale mesoscopic heterogeneities. Laboratory and field measurements of seismic attenuation in fluid-saturated rocks provide indications of the role of the wave-induced flow. Signatures of wave-induced flow include the frequency and saturation dependence of P-wave attenuation and its associated velocity dispersion, frequency-dependent shear-wave splitting, and attenuation anisotropy. During the last four decades, numerous models for attenuation and velocity dispersion from wave-induced flow have been developed with varying degrees of rigor and complexity. These models can be categorized roughly into three groups ac-cording to their underlying theoretical framework. The first group of models is based on Biot’s theory of poroelasticity. The second group is based on elastodynamic theory where local fluid flow is incorporated through an additional hydrodynamic equation. Another group of models is derived using the theory of viscoelasticity. Though all models predict attenuation and velocity dispersion typical for a relaxation process, there exist differences that can be related to the type of disorder (periodic, random, space dimension) and to the way the local flow is incorporated. The differences manifest themselves in different asymptotic scaling laws for attenuation and in different expressions for characteristic frequencies. In recent years, some theoretical models of wave-induced fluid flow have been validated numerically, using finite-difference, finite-element, and reflectivity algorithms applied to Biot’s equations of poroelasticity. Application of theoretical models to real seismic data requires further studies using broadband laboratory and field measurements of attenuation and dispersion for different rocks as well as development of more robust methods for estimating dissipation attributes from field data.

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