The Experts below are selected from a list of 288 Experts worldwide ranked by ideXlab platform
Shidong Li - One of the best experts on this subject based on the ideXlab platform.
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the impact of nanoparticle adsorption on transport and wettability alteration in water wet Berea Sandstone an experimental study
Frontiers in Physics, 2019Co-Authors: Shidong Li, Ole Torsaeter, Nanji J Hadia, Ludger P StubbsAbstract:Wettability alteration was proposed as one of the enhanced oil recovery (EOR) mechanisms for nanoparticle fluid (nanofluid) flooding. The effect of nanoparticle adsorption on wettability alteration was investigated by wettability index measurement of Berea Sandstone core injected with nanofluids and by contact angle measurement of a glass surface treated with nanofluids. Nanoparticle adsorption was studied by single phase coreflooding with nanofluids in Berea Sandstone. The adsorption isotherm and the impact of adsorption on the effective permeability were investigated by measuring the effluent nanoparticle concentration and differential pressure across the core. Results showed that hydrophilic nanoparticles (e.g. fumed silica) made the core slightly more water wet, and hydrophobic nanoparticles (e.g. silane modified fumed silica) delayed spontaneous imbibition but could not alter the original wettability. It was found that hydrophilic nanoparticles treatment reduced contact angle between oil and water by about 10 to 20 degree for a glass surface. Results also showed that different types of nanoparticle have different adsorption and desorption behavior and different ability to impair the permeability of Berea Sandstones cores.
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effect of silica nanoparticles adsorption on the wettability index of Berea Sandstone
2013Co-Authors: Shidong Li, Anne Tinnen Kaasa, Luky Hendraningrat, Ole TorsaeterAbstract:ABSTRACT Nanotechnology has already drawn attentions in the oil and gas industry for its many potential applications in exploration and production processes, especially in the enhanced oil recovery (EOR) area. Nanoparticles, as a part of nanotechnology have been suggested as a promising EOR method in the future. Some EOR mechanisms for nanoparticle have already been proposed, such as disjoining pressure gradient, interfacial tension reduction, wettability alteration and plugging of big pore channels. Hence, the study objective of this paper is to investigate the effect of silica nanoparticle adsorption on the wettability index for Berea Sandstone. In this experimental study, both hydrophilic and hydrophobic silica nanoparticles with 7 nm average particle size were used. Water wet and neutral wet Berea Sandstone cores with 250-450 mD permeability were selected as porous media. Three weight percent (3 wt. %) NaCl brine and ethanol were used as suspension fluids for hydrophilic and hydrophobic silica nanoparticles respectively, and the wettability index of Berea Sandstone treated by nanoparticle was measured using Amott method. The results indicated that the hydrophilic nanoparticles can make neutral wet cores more water wet and increase the wettability index of water wet cores about 10%. The hydrophobic nanoparticles can delay the imbibition process for water wet cores but have no significant effect on wettability change. While for neutral wet cores the high concentration hydrophobic nanoparticles suspension can make it more oil wet. The adsorption and retention of nanoparticles in porous media can reduce its porosity and permeability.
Nicola Tisato - One of the best experts on this subject based on the ideXlab platform.
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laboratory measurements of seismic wave attenuation in Berea Sandstone as a function of water saturation and confining pressure
Seg Technical Program Expanded Abstracts, 2015Co-Authors: Samuel Chapman, Nicola Tisato, Beatriz Quintal, Klaus HolligerAbstract:We measure extensional-mode attenuation and dynamic Young’s modulus on a Berea Sandstone sample at seismic frequencies (0.5-50 Hz). The results show a dependence of attenuation with frequency, water saturation and confining pressure. For water saturation levels above 80%, we observe a frequency-dependent bell-shaped attenuation curve with a peak between 1 and 20 Hz. For dry conditions, attenuation is very low and approximately frequencyindependent. Increasing the confining pressure on the sample causes a reduction of the overall magnitude of the attenuation. The results indicate that the frequencydependent attenuation can be attributed to mesoscopic wave-induced fluid flow (WIFF) caused by heterogeneities in water saturation.
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measurements of seismic attenuation and transient fluid pressure in partially saturated Berea Sandstone evidence of fluid flow on the mesoscopic scale
Geophysical Journal International, 2013Co-Authors: Nicola Tisato, Beatriz QuintalAbstract:S U M M A R Y A novel laboratory technique is proposed to investigate wave-induced fluid flow on the mesoscopic scale as a mechanism for seismic attenuation in partially saturated rocks. This technique combines measurements of seismic attenuation in the frequency range from 1 to 100 Hz with measurements of transient fluid pressure as a response of a step stress applied on top of the sample. We used a Berea Sandstone sample partially saturated with water. The laboratory results suggest that wave-induced fluid flow on the mesoscopic scale is dominant in partially saturated samples. A 3-D numerical model representing the sample was used to verify the experimental results. Biot’s equations of consolidation were solved with the finite-element method. Wave-induced fluid flow on the mesoscopic scale was the only attenuation mechanism accounted for in the numerical solution. The numerically calculated transient fluid pressure reproduced the laboratory data. Moreover, the numerically calculated attenuation, superposed to the frequency-independent matrix anelasticity, reproduced the attenuation measured in the laboratory in the partially saturated sample. This experimental—numerical fit demonstrates that wave-induced fluid flow on the mesoscopic scale and matrix anelasticity are the dominant mechanisms for seismic attenuation in partially saturated Berea Sandstone.
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low frequency measurements of seismic wave attenuation in Berea Sandstone
Seg Technical Program Expanded Abstracts, 2011Co-Authors: Nicola Tisato, Claudio Madonna, Brad Artman, Erik H SaengerAbstract:We have designed and set up a pressure vessel for 250 mm long and 76 mm in diameter cylindrical samples to measure seismic wave attenuation in rocks at frequencies between 0.01 and 100 Hz and to verify the occurrence of fluid-flow induced by stress field changes. A dynamic stress is applied at the top of the rock cylinder by a piezoelectric motor generating either a stress step of several kPa in few milliseconds or a mono-frequency force. A load cell measures force and a strain sensor the bulk axial shortening across the sample. Five pressure sensors are buried at different heights of the cylinder to measure pore pressure changes related to stress field changes. The sample is sealed in a pressure vessel that can reach confining pressures of 25 MPa. We present datasets collected at room pressure and temperature. Three attenuation data curves measured on reference samples demonstrate the accuracy of the apparatus. A test of the influence of the static stress applied on the sample on the attenuation measurements and measurements conducted for frequencies between 0.1 and 50 Hz with strain < 5e-6 on partially saturated Berea Sandstone are presented. Timeevolution pore-pressure curves due to stress field changes are also given.
Beatriz Quintal - One of the best experts on this subject based on the ideXlab platform.
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laboratory measurements of seismic wave attenuation in Berea Sandstone as a function of water saturation and confining pressure
Seg Technical Program Expanded Abstracts, 2015Co-Authors: Samuel Chapman, Nicola Tisato, Beatriz Quintal, Klaus HolligerAbstract:We measure extensional-mode attenuation and dynamic Young’s modulus on a Berea Sandstone sample at seismic frequencies (0.5-50 Hz). The results show a dependence of attenuation with frequency, water saturation and confining pressure. For water saturation levels above 80%, we observe a frequency-dependent bell-shaped attenuation curve with a peak between 1 and 20 Hz. For dry conditions, attenuation is very low and approximately frequencyindependent. Increasing the confining pressure on the sample causes a reduction of the overall magnitude of the attenuation. The results indicate that the frequencydependent attenuation can be attributed to mesoscopic wave-induced fluid flow (WIFF) caused by heterogeneities in water saturation.
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measurements of seismic attenuation and transient fluid pressure in partially saturated Berea Sandstone evidence of fluid flow on the mesoscopic scale
Geophysical Journal International, 2013Co-Authors: Nicola Tisato, Beatriz QuintalAbstract:S U M M A R Y A novel laboratory technique is proposed to investigate wave-induced fluid flow on the mesoscopic scale as a mechanism for seismic attenuation in partially saturated rocks. This technique combines measurements of seismic attenuation in the frequency range from 1 to 100 Hz with measurements of transient fluid pressure as a response of a step stress applied on top of the sample. We used a Berea Sandstone sample partially saturated with water. The laboratory results suggest that wave-induced fluid flow on the mesoscopic scale is dominant in partially saturated samples. A 3-D numerical model representing the sample was used to verify the experimental results. Biot’s equations of consolidation were solved with the finite-element method. Wave-induced fluid flow on the mesoscopic scale was the only attenuation mechanism accounted for in the numerical solution. The numerically calculated transient fluid pressure reproduced the laboratory data. Moreover, the numerically calculated attenuation, superposed to the frequency-independent matrix anelasticity, reproduced the attenuation measured in the laboratory in the partially saturated sample. This experimental—numerical fit demonstrates that wave-induced fluid flow on the mesoscopic scale and matrix anelasticity are the dominant mechanisms for seismic attenuation in partially saturated Berea Sandstone.
B J Smith - One of the best experts on this subject based on the ideXlab platform.
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effects of partial liquid gas saturation on extensional wave attenuation in Berea Sandstone
Geophysical Research Letters, 1992Co-Authors: M L Batzle, B J SmithAbstract:Extensional wave attenuation measurements on Berea Sandstone were made during increasing (imbibition) and decreasing (drainage) brine saturations. Measurements on samples with both open-pore and closed-pore surfaces were made using the resonant-bar technique. The frequency dependence was examined using the forced-deformation method. The attenuation was found to be dependent on saturation history as well as degree of saturation and boundary flow conditions. The sample with open-pore surface had a larger attenuation which peaked at greater brine saturations than the sample with closed-pore surface. During drainage, the attenuation reached a maximum at about 90% brine saturation as opposed to about 97% brine saturation during imbibition. The variation of the size and number of air pockets within the rock can account for this discrepancy. The magnitude of the attenuation peak value decreases substantially with decreasing frequency to the extent that no attenuation peak with saturation was apparent at seismic frequencies, say, below 100 Hz.
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Effects of partial liquid/gas saturation on extensional wave attenuation in Berea Sandstone
Geophysical Research Letters, 1992Co-Authors: M L Batzle, B J SmithAbstract:Extensional wave attenuation measurements on Berea Sandstone were made during increasing (imbibition) and decreasing (drainage) brine saturations. Measurements on samples with both open-pore and closed-pore surfaces were made using the resonant-bar technique. The frequency dependence was examined using the forced-deformation method. The attenuation was found to be dependent on saturation history as well as degree of saturation and boundary flow conditions. The sample with open-pore surface had a larger attenuation which peaked at greater brine saturations than the sample with closed-pore surface. During drainage, the attenuation reached a maximum at about 90% brine saturation as opposed to about 97% brine saturation during imbibition. The variation of the size and number of air pockets within the rock can account for this discrepancy. The magnitude of the attenuation peak value decreases substantially with decreasing frequency to the extent that no attenuation peak with saturation was apparent at seismic frequencies, say, below 100 Hz.
Thomas J Shankland - One of the best experts on this subject based on the ideXlab platform.
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modeling of stress strain dependences for Berea Sandstone under quasistatic loading
Physical Review B, 2007Co-Authors: Vyacheslav O Vakhnenko, Oleksiy O Vakhnenko, James A Tencate, Thomas J ShanklandAbstract:In this work, a phenomenological model to describe the complex stress-strain properties of a Sandstone sample under slow loading is presented. We consider a combination of three methods to treat the elastic and nonlinear behavior observed in stress cycling experiments. The mechanisms to treat interior equilibration processes in Sandstone are termed the standard solid relaxation mechanism, the sticky-spring mechanism, and the permanent plastic deformation mechanism. With a small number of parameters, the overall model displays both qualitatively and quantitatively the principal experimental observations of the stress-strain trajectories for Berea Sandstone, in particular, the details of end-point memory under quasistatic loading.
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slow dynamics in the nonlinear elastic response of Berea Sandstone
Geophysical Research Letters, 1996Co-Authors: James Ten A Cate, Thomas J ShanklandAbstract:A typical resonance curve--measured accel- eration versus drive frequency--made on a thin bar of rock shows peak bending with a softening (nonlinear) modulus as drive levels are increased. The shapes of these nonlinear resonance curves were found in earlier work to depend somewhat on sweep rate; these "slow dynamics" are now examined and quantified. We have measured slow dynamics in a 0.3 m long, 50 mm diam- eter bar of Berea Sandstone under ambient conditions. Peak strain levels during the experiments ranged from 10- • • to 10 -• at driving frequencies near 4 kHz, the fun- damental longitudinal resonance frequency of the bar. Slow dynamics begin to manifest themselves at strain amplitudes above 10 -a at ambient conditions and at the onset of nonlinear peak bending. Strains above this value condition the rock, altering its response for min- utes to hours after the drive has been turned off. ter the pressure on the rock was changed. The work presented here is the first to specifically document the slowly varying time response to periodic excitation (i.e., slow dynamics) of a Berea Sandstone sample; moreover, we demonstrate that the slow dynamics produce promi- nent effects, even at room conditions. Slow dynamics manifest themselves in a Sandstone sample during high intensity longitudinal elastic reso- nance. We first report the effects of high strain on a sample by comparing "conditioned" resonance curves (e.g., after the sample is driven at high intensity) with a set of fully "recovered" curves (e.g., after the sample is left untouched for a long period). We illustrate that the first resonance curve made on a recovered sample differs remarkably from subsequent curves. We present several results that illustrate aspects of the sample's memory and concludiwith a discussion of measurements to de- termine how the rock recovers and to understand what
