Comparison of Fluid Pressure Wave between Biot Theory and Storativity Equation

Compressibilities of pore fluid and rock skeleton affect pressure profile and flow velocity of fluid in aquifers. Storativity equation is often used to characterize such effects. The equation suffers from a disadvantage that at infinite large frequency, the predicted velocity of fluid pressure wave is infinitely large, which is unrealistic because any physical processes need certain amounts of time. In this paper, Biot theory is employed to investigate the problem. It is shown that the key equations of Biot theory can be simplified to storativity equation, based on low-frequency assumption. Using Berea sandstone as an example, we compare phase velocity and the quality factor between Biot theory and storativity equation. The results reveal that Biot theory is more accurate in yielding a bounded wave velocity. At frequency lower than 100 kHz, Biot theory yields a wave velocity 8 percent higher than storativity equation does. Apparent permeability measured by fluid pressure wave (such as Oscillatory Hydraulic Tomography) may be 14 percent higher than real permeability measured by steady flow experiments. If skeleton is rigid, Biot theory at very high frequencies or with very high permeabilities will yield the same velocity as sound wave in pure water. The findings help us for better understanding of the physical processes of pore fluid and the limitations of storativity equation.

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Anomalous Vp/Vs in highly pressurized rocks: Evidence for anisotropy or mafic composition?

10.5194/egusphere-egu2020-15845 ◽

2020 ◽

Author(s):

Lucas Pimienta ◽

Alexandre Schubnel ◽

Jerome Fortin ◽

Yves Guéguen ◽

Helene Lyon-Caen ◽

...

Keyword(s):

Subduction Zones ◽

Laboratory Data ◽

Fluid Pressure ◽

Pore Fluid ◽

S Wave ◽

Pore Fluid Pressure ◽

Crustal Rocks ◽

High Fluid ◽

Measuring Frequency ◽

Very High

<p>&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; Anomalously high seismic P- to S-wave velocity ratios (Vp/Vs) have been observed in subduction zones, in locations where varieties of earthquakes and slips are expected to occur. From qualitative laboratory knowledge of rocks Poisson&#8217;s ratio, these results were interpreted as evidence of near-lithostatic pore fluid pressure. Because most laboratory data did not document such high Vp/Vs values, these were further linked to additional constrains of anisotropy or the dominance of minerals of very high intrinsic Vp/Vs, e.g. mafic rocks.However, does high Vp/Vs necessarily imply anisotropy and/or mafic composition?</p><p>&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; Recently, the measuring frequency (f) was shown to play a major role on rocks&#8217; resulting Poisson&#8217;s ratio, so that usual laboratory results (at f = 1 MHz) might not directly transfer to field ones (at f = 1 Hz). From this consideration, we investigate Vp/Vs of a variety of crustal rocks in the elastic regime relevant at the field scale, the undrained elastic regime.Accounting for rocks dispersive properties, this work aims to show that:</p><ul><li>In the laboratory, in isotropic rocks, one might attain Vp/Vs values as high as the anomalous ones observed in subduction zones.</li> <li>No mineralogical control is needed for such high Vp/Vs values, which could be consistent with the inherent mineral variability in different settings across the globe.</li> <li>High pore fluid pressure is a major parameter, but not alone: such high values cannot be achieved without very high degree of micro-fracturing of the rock, opened by high fluid pressures, an information of potential importance to understand those seismogenic zones.</li> </ul>

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Measurement of regional pulse wave velocity using very high frame rate ultrasound

Choonpa Igaku ◽

10.3179/jjmu.jjmu.k.8 ◽

2015 ◽

Vol 42 (6) ◽

pp. 701-709

Author(s):

Hideyuki HASEGAWA ◽

Kazue HONGO ◽

Hiroshi KANAI

Keyword(s):

Pulse Wave Velocity ◽

Wave Velocity ◽

Pulse Wave ◽

Frame Rate ◽

High Frame Rate ◽

Very High

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Experimental Investigation of Wave Velocity-Permeability Model for Granite Subjected to Different Temperature Processing

Geofluids ◽

10.1155/2017/6586438 ◽

2017 ◽

Vol 2017 ◽

pp. 1-10 ◽

Cited By ~ 2

Author(s):

Guanghui Jiang ◽

Jianping Zuo ◽

Teng Ma ◽

Xu Wei

Keyword(s):

Particle Size ◽

High Temperature ◽

Wave Velocity ◽

Pore Fluid ◽

Rock Matrix ◽

Permeability Model ◽

Wave Velocities ◽

Before And After ◽

Different Temperatures ◽

Increasing Temperature

Understanding the change of permeability of rocks before and after heating is of great significance for exploitation of hydrocarbon resources and disposal of nuclear waste. The rock permeability under high temperature cannot be measured with most of the existing methods. In this paper, quality, wave velocity, and permeability of granite specimen from Maluanshan tunnel are measured after high temperature processing. Quality and wave velocity of granite decrease and permeability of granite increases with increasing temperature. Using porosity as the medium, a new wave velocity-permeability model is established with modified wave velocity-porosity formula and Kozeny-Carman formula. Under some given wave velocities and corresponding permeabilities through experiment, the permeabilities at different temperatures and wave velocities can be obtained. By comparing the experimental and the theoretical results, the proposed formulas are verified. In addition, a sensitivity analysis is performed to examine the effect of particle size, wave velocities in rock matrix, and pore fluid on permeability: permeability increases with increasing particle size, wave velocities in rock matrix, and pore fluid; the higher the rock wave velocity, the lower the effect of wave velocities in rock matrix and pore fluid on permeability.

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Correction to: Stress and pore fluid pressure control of seismicity rate changes following the 2016 Kumamoto earthquake, Japan

Earth Planets and Space ◽

10.1186/s40623-021-01358-8 ◽

2021 ◽

Vol 73 (1) ◽

Author(s):

Kodai Nakagomi ◽

Toshiko Terakawa ◽

Satoshi Matsumoto ◽

Shinichiro Horikawa

Keyword(s):

Fluid Pressure ◽

Pressure Control ◽

Pore Fluid ◽

2016 Kumamoto Earthquake ◽

Pore Fluid Pressure ◽

Seismicity Rate ◽

Kumamoto Earthquake ◽

The 2016 Kumamoto Earthquake ◽

Seismicity Rate Changes

An amendment to this paper has been published and can be accessed via the original article.

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Two-phase pore-fluid distribution in fractured media: acoustic wave velocity vs saturation

Applied Geophysics ◽

10.1007/s11770-018-0686-5 ◽

2018 ◽

Vol 15 (2) ◽

pp. 311-317

Author(s):

Xi Duan ◽

Xiang-Jun Liu

Keyword(s):

Acoustic Wave ◽

Wave Velocity ◽

Fractured Media ◽

Pore Fluid ◽

Fluid Distribution ◽

Two Phase ◽

Acoustic Wave Velocity

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Liquefaction hazard zonation mapping of the Saitama City, Japan

Journal of Nepal Geological Society ◽

10.3126/jngs.v40i0.23598 ◽

2010 ◽

Vol 40 ◽

pp. 69-76 ◽

Cited By ~ 1

Author(s):

Rama Mohan Pokhrel ◽

Jiro Kuwano ◽

Shinya Tachibana

Keyword(s):

Shear Wave ◽

Wave Velocity ◽

Shear Wave Velocity ◽

Hazard Zonation ◽

Liquefaction Potential ◽

Amplification Ratio ◽

Liquefaction Hazard ◽

Clayey Silt ◽

The City ◽

Very High

Liquefaction hazard zonation mapping of the Saitama City targeted on the Kanto Plain NW Edge Fault is described in this paper. The study involves the geotechnical properties of the alluvial soil of the city including Standard Penetration Test (SPT), shear wave velocity and other geological data analysis. The city being highly urbanized is situated on the soft soil (alluvial deposits) at the proximity of an active seismic fault that has increased the possibility of liquefaction hazard in the area. Kanto Plain NW Edge Fault is an active fault that lies very near to the Saitama City having the estimated possible earthquake magnitude of 7.4. The possible peak horizontal ground acceleration (amax) from this earthquake is calculated as from 0.15 g to 0.30 g. By considering all possible acceleration values the liquefaction potential maps were prepared and presented in this paper. Additionally, the shear wave velocity is very low and amplification ratio is very high at the marshy deposit but it has comparatively high velocity and low amplification ratio at the marine loam deposit area of the Omiya Plateau. In this paper the liquefaction potential of the area is expressed in terms of liquefaction potential index (PL). The PL value for the clayey silt deposit in the marshy area with shallow water table is very high. In addition, the PL value in the marine loam deposit of the Omiya Plateau is less which indicates that loam deposit has less liquefaction potential than marshy deposit. The map obtained from this study was validated with the field condition of the study area. Hence, it is expected that this study will assist in characterizing the seismic hazards and its mitigation and will provide valuable information for urban planning in the study area in future.

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Pemodelan Penurunan Tekanan Brine di Dalam Pipa Injeksi pada Lapangan Panas Bumi Dieng

Jurnal MIPA ◽

10.35799/jm.6.2.2017.17332 ◽

2017 ◽

Vol 6 (2) ◽

pp. 32

Author(s):

Jeferson Polii

Keyword(s):

Pressure Drop ◽

Flow Line ◽

Chemical Constituents ◽

Temperature Drop ◽

Fluid Pressure ◽

Saturation Temperature ◽

Geothermal Field ◽

Chemical Pollution ◽

Pressure Drops ◽

Very High

Injeksi brine hasil dari fluida produksi panas bumi digunakan untuk mengisi volume pori batuan reservoir, mencegah penurunan tekanan batuan yang terlalu cepat, dan mencegah polusi panas dan polusi kimia pada lingkungan yang disebabkan oleh kandungan kimia tertentu pada brine. Pada pipa aliran brine terjadi penurunan tekanan fluida sepanjang aliran. Di lapangan panas bumi Dieng, konsentrasi silika sangat tinggi, sehingga penurunan temperatur saturasi memicu desposisi silika. Penurunan tekanan sepanjang pipa aliran brine dari pompa Vertikal Atas (VA) 7 ke pond di pad 29 di lapangan panas bumi Dieng akan menyebabkan penurunan temperatur saturasi, selain juga kehilangan panas secara alami. Perhitungan penurunan tekanan fluida brine berdasarkan perhitungan Harrison-Freeston dan metode dari Zhao, yang dikembangkan dengan algoritma menggunakan Macro Excel. Sehingga dengan memodelkan penurunan tekanan sepanjang pipa alir, dapat dikembangkan untuk perhitungan penurunan temperatur dan pengendapan silika di pipa aliran brine untuk injeksi panas bumi.Brine injection from geothermal production fluids is used to fill reservoir pore rock volumes, preventing rapid rock pressure drops, and preventing heat pollution and chemical pollution in the environment caused by certain chemical constituents in the brine. Decrease fluid pressure along the flow on the brine flow pipe. In the Dieng geothermal field, the silica concentration is very high, so the decrease in saturation temperature triggers the silica desposition. The pressure drop along the brine flow pipe from the Upper Vertical (VA) 7 pump to the pond in pad 29 in Dieng geothermal field will cause a decrease in saturation temperature, as well as natural heat loss. The calculation of the decrease in brine fluid pressure based on Harrison-Freeston calculations and methods of Zhao, developed with algorithms using Macro Excel. By modeling the pressure drop along the flow line, it can be developed for the calculation of temperature drop and deposition of silica in the brine flow pipe for geothermal injection

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Calculation Analysis of Pressure Wave Velocity in Gas and Drilling Mud Two-Phase Fluid in Annulus during Drilling Operations

Mathematical Problems in Engineering ◽

10.1155/2013/318912 ◽

2013 ◽

Vol 2013 ◽

pp. 1-17 ◽

Cited By ~ 8

Author(s):

Yuanhua Lin ◽

Xiangwei Kong ◽

Yijie Qiu ◽

Qiji Yuan

Keyword(s):

Wave Velocity ◽

Void Fraction ◽

Pressure Wave ◽

Angular Frequency ◽

Mass Force ◽

Virtual Mass ◽

Drilling Mud ◽

Influx Rate ◽

Drilling Operations ◽

Well Depth

Investigation of propagation characteristics of a pressure wave is of great significance to the solution of the transient pressure problem caused by unsteady operations during management pressure drilling operations. With consideration of the important factors such as virtual mass force, drag force, angular frequency, gas influx rate, pressure, temperature, and well depth, a united wave velocity model has been proposed based on pressure gradient equations in drilling operations, gas-liquid two-fluid model, the gas-drilling mud equations of state, and small perturbation theory. Solved by adopting the Runge-Kutta method, calculation results indicate that the wave velocity and void fraction have different values with respect to well depth. In the annulus, the drop of pressure causes an increase in void fraction along the flow direction. The void fraction increases first slightly and then sharply; correspondingly the wave velocity first gradually decreases and then slightly increases. In general, the wave velocity tends to increase with the increase in back pressure and the decrease of gas influx rate and angular frequency, significantly in low range. Taking the virtual mass force into account, the dispersion characteristic of the pressure wave weakens obviously, especially at the position close to the wellhead.

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