Experimental study on frequency-dependent elastic properties of weakly consolidated marine sandstone: effects of partial saturation
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Experimental study on frequency-dependent elastic properties of weakly consolidated marine sandstone : effects of partial saturation. / Li, Hui; Zhao, Luanxiao; Han, De hua; Gao, Jinghuai; Yuan, Hemin; Wang, Yirong.
I: Geophysical Prospecting, Bind 68, Nr. 9, 2020, s. 2808-2824.Publikation: Bidrag til tidsskrift › Tidsskriftartikel › Forskning › fagfællebedømt
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TY - JOUR
T1 - Experimental study on frequency-dependent elastic properties of weakly consolidated marine sandstone
T2 - effects of partial saturation
AU - Li, Hui
AU - Zhao, Luanxiao
AU - Han, De hua
AU - Gao, Jinghuai
AU - Yuan, Hemin
AU - Wang, Yirong
N1 - Publisher Copyright: © 2020 European Association of Geoscientists & Engineers
PY - 2020
Y1 - 2020
N2 - Investigating seismic dispersion and attenuation characteristics of loosely compacted marine sandstone is essential in reconciling different geophysical measurements (surface seismic, well logging and ultrasonic) for better characterization of a shallow marine sandstone reservoir. We have experimented with a typical high-porosity and high-permeability sandstone sample, extracted from the Paleogene marine depositional setting in the Gulf of Mexico, at the low-frequency band (2–500 Hz) as well as ultrasonic point (106 Hz), to investigate the effects of varying saturation levels on a rock's elasticity. The results suggest that the Young's modulus of the measured sample with adsorbed moisture at laboratory conditions (room temperature, 60%–90% humidity) exhibits dispersive behaviours. The extensional attenuation can be as high as 0.038, and the peak frequency occurs around 60 Hz. The extensional attenuation due to moisture adsorption can be dramatically mitigated with the increase of confining pressure. For partial saturation status, extensional attenuation increases as increasing water saturation by 79% with respect to the measured frequencies. Additionally, the results show that extensional attenuation at the fully water-saturated situation is even smaller than that at adsorbed moisture conditions. The Gassmann–Wood model can overall capture the P-wave velocity-saturation trend of measured data at seismic frequencies, demonstrating that the partially saturated unconsolidated sandstone at the measured seismic frequency range is prone to be in the relaxed status. Nevertheless, the ultrasonic velocities are significantly higher than the Gassmann–Wood predictions, suggesting that the rocks are in the unrelaxed status at the ultrasonic frequency range. The poroelastic modelling results based on the patchy saturation model also indicate that the characteristic frequency of the partially saturated sample is likely beyond the measured seismic frequency range.
AB - Investigating seismic dispersion and attenuation characteristics of loosely compacted marine sandstone is essential in reconciling different geophysical measurements (surface seismic, well logging and ultrasonic) for better characterization of a shallow marine sandstone reservoir. We have experimented with a typical high-porosity and high-permeability sandstone sample, extracted from the Paleogene marine depositional setting in the Gulf of Mexico, at the low-frequency band (2–500 Hz) as well as ultrasonic point (106 Hz), to investigate the effects of varying saturation levels on a rock's elasticity. The results suggest that the Young's modulus of the measured sample with adsorbed moisture at laboratory conditions (room temperature, 60%–90% humidity) exhibits dispersive behaviours. The extensional attenuation can be as high as 0.038, and the peak frequency occurs around 60 Hz. The extensional attenuation due to moisture adsorption can be dramatically mitigated with the increase of confining pressure. For partial saturation status, extensional attenuation increases as increasing water saturation by 79% with respect to the measured frequencies. Additionally, the results show that extensional attenuation at the fully water-saturated situation is even smaller than that at adsorbed moisture conditions. The Gassmann–Wood model can overall capture the P-wave velocity-saturation trend of measured data at seismic frequencies, demonstrating that the partially saturated unconsolidated sandstone at the measured seismic frequency range is prone to be in the relaxed status. Nevertheless, the ultrasonic velocities are significantly higher than the Gassmann–Wood predictions, suggesting that the rocks are in the unrelaxed status at the ultrasonic frequency range. The poroelastic modelling results based on the patchy saturation model also indicate that the characteristic frequency of the partially saturated sample is likely beyond the measured seismic frequency range.
KW - Elastic dispersion
KW - Extensional attenuation
KW - Forced-oscillation measurement
KW - Partially saturated marine sandstone
U2 - 10.1111/1365-2478.13031
DO - 10.1111/1365-2478.13031
M3 - Journal article
AN - SCOPUS:85092107185
VL - 68
SP - 2808
EP - 2824
JO - Geophysical Prospecting
JF - Geophysical Prospecting
SN - 0016-8025
IS - 9
ER -
ID: 270674268