scholarly journals Correlation of Pore-Pressure B-Value with P-Wave Velocity and Poisson’s Ratio for Imperfectly Saturated Sand or Gravel

2000 ◽  
Vol 40 (4) ◽  
pp. 95-102 ◽  
Author(s):  
Takeji Kokusho
Keyword(s):  
Pore Pressure ◽  
Wave Velocity ◽  
Poisson’S Ratio ◽  
B Value ◽  
P Wave ◽  
Poisson's Ratio ◽  
Saturated Sand ◽  
P Wave Velocity

scholarly journals Experimental Investigation on the Correlation between Dynamic Ultrasonic and Mechanical Properties of Sandstone Subjected to Uniaxial Compression

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-22
Author(s):  
Yunjiang Sun ◽  
Jianping Zuo ◽  
Yue Shi ◽  
Zhengdai Li ◽  
Changning Mi ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Young’S Modulus ◽  
Ultrasonic Wave ◽  
Uniaxial Compression ◽  
Wave Velocity ◽  
Poisson’S Ratio ◽  
P Wave ◽  
Poisson's Ratio ◽  
Ultrasonic Wave Velocity ◽  
P Wave Velocity

Ultrasonic wave velocity is effective to evaluate anisotropy property and predict rock failure. This paper investigates the correlation between dynamic ultrasonic and mechanical properties of sandstones with different buried depths subjected to uniaxial compression tests. The circumferential anisotropy and axial wave velocity of sandstone are obtained by means of ultrasonic wave velocity measurements. The mechanical properties, including Young’s modulus and uniaxial compressive strength, are positively correlated with the axial P wave velocity. The average angles between the sandstone failure plane and the minimum and maximum wave directions are 35.8° and 63.3°, respectively. The axial P wave velocity almost keeps constant, and the axial S wave velocity has a decreasing trend before the failure of rock specimen. In most rock samples under uniaxial compression, shear failure occurs in the middle and splitting appears near both sides. Additionally, the dynamic Young’s modulus and dynamic Poisson’s ratio during loading are obtained, and the negative values of the Poisson’s ratio occur at the initial compression stage. Distortion and rotation of micro/mesorock structures may be responsible for the negative Poisson’s ratio.

Crosswell seismic radial survey tomograms and the 3-D interpretation of a heavy oil steamflood

Geophysics ◽  
1995 ◽  
Vol 60 (3) ◽  
pp. 651-659 ◽  
Author(s):  
Mark E. Mathisen ◽  
Paul Cunningham ◽  
Jesse Shaw ◽  
Anthony A. Vasiliou ◽  
J. H. Justice ◽  
...  
Keyword(s):  
Data Quality ◽  
Wave Velocity ◽  
Heavy Oil ◽  
Poisson’S Ratio ◽  
High Flow ◽  
P Wave ◽  
Poisson's Ratio ◽  
S Wave ◽  
P Wave Velocity ◽  
Steam Heat

S‐wave, P‐wave, and Poisson’s ratio tomograms have been used to interpret the 3-D distribution of rock and fluid properties during an early phase of a California heavy oil sand steamflood. Four lines of good quality crosswell seismic data, with source to receiver offsets ranging from 287 to 551 ft (87 to 168 m), were acquired in a radial pattern around a high temperature cemented receiver cable in four days. Processing, first‐arrival picking, and good quality tomographic reconstructions were completed despite offset‐related variations in data quality between the long and short lines. Interpretation was based on correlations with reservoir models, log, core, temperature, and steam injection data. S‐wave tomograms define the 3-D distribution of the “high flow” turbidite channel facies, the “moderate‐low flow” levee facies, porosity, and structural dip. The S‐wave tomograms also define an area with anomalously low S‐wave velocity, which correlates with low shear log velocities and suggests that pressure‐related dilation and compaction may be imageable. P‐wave tomograms define the same reservoir lithology and structure as the S‐wave tomograms and the 3-D distribution of low compressional velocity zones formed by previous steam‐heat injection and the formation of gas. The low P‐wave velocity zones, which are laterally continuous in the “high flow” channel facies near the top of most zones, indicate that the steam‐heat‐gas distribution is controlled by stratification. The stratigraphic control of gas‐bearing zones inferred from P‐wave tomograms is confirmed by Poisson’s ratio tomograms which display low Poisson’s ratios indicative of gas (<0.35) in the same zones as the low P‐wave velocities. The interpretation results indicate that radial survey tomograms can be tied at a central well and used to develop an integrated 3-D geoscience‐engineering reservoir model despite offset‐related variations in data quality. The laterally continuous, stratification‐controlled, low P‐wave velocity zones, which extend up‐dip, suggest that significant amounts of steam‐heat are not heating the surrounding reservoir volume but are flowing updip along “high flow” channels.

scholarly journals Effects of Air Bubbles on B-Value and P-Wave Velocity of a Partly Saturated Sand.

2002 ◽  
Vol 42 (1) ◽  
pp. 121-129 ◽  
Author(s):  
SHUJI TAMURA ◽  
KOHJI TOKIMATSU ◽  
AKIO ABE ◽  
MASAYOSHI SATO
Keyword(s):  
Wave Velocity ◽  
B Value ◽  
P Wave ◽  
Air Bubbles ◽  
Saturated Sand ◽  
P Wave Velocity

A geophysical model for the Kapuskasing uplift from seismic and gravity studies

1991 ◽  
Vol 28 (3) ◽  
pp. 342-354 ◽  
Author(s):  
A. V. Boland ◽  
R. M. Ellis
Keyword(s):  
Cross Section ◽  
Wave Velocity ◽  
Poisson’S Ratio ◽  
Gravity Anomalies ◽  
P Wave ◽  
Poisson's Ratio ◽  
S Wave ◽  
Low Velocity ◽  
Cross Sectional ◽  
P Wave Velocity

The Kapuskasing uplift is an oblique cross section of Archean crust exposed by a major thrusting event in Early Proterozoic times. Previous results from the traveltime and amplitude analysis of compressional-wave (P-wave) arrivals from a seismic-refraction experiment have been used to constrain the modelling of shear-wave (S-wave) arrivals and gravity anomalies along the seismic profiles. S-wave and P-wave velocity information have been combined to obtain the variations of Poisson's ratio within the crust. High and low Poisson's ratio values have been linked to the mafic and felsic content, respectively, of the Shield rocks. Density variations along the profiles, constrained by the P-wave velocity structures and the observed gravity anomalies, again have been linked to the lithological variations as observed in the exposed cross section. Geological models, constrained by the geophysical observations and the cross-sectional exposure, have been constructed for profiles across the northern and southern portions of the main uplift region. The results indicate an increase in pyroxene and garnetiferous gneisses with depth in the crust, as suggested by the high P-wave velocities (7.0–7.6 km/s), high densities (3050–3150 kg/m3, high Poisson's ratio values (0.26–0.28), and the petrological variations within the exposure. The presence of a low-velocity and low-density layer of tonalites under the surface greenstones has been established and can account for the low-velocity zones imaged along the Abitibi profile of this experiment and those imaged in other Shield refraction experiments.

scholarly journals Time-average velocity estimation through surface-wave analysis: Part 2 — P-wave velocity

Geophysics ◽  
2017 ◽  
Vol 82 (3) ◽  
pp. U61-U73 ◽  
Author(s):  
Laura Valentina Socco ◽  
Cesare Comina
Keyword(s):  
Wave Velocity ◽  
Poisson’S Ratio ◽  
Average Velocity ◽  
P Wave ◽  
Poisson's Ratio ◽  
S Wave ◽  
Seismic Line ◽  
Velocity Models ◽  
P Wave Velocity ◽  
Time Average

Surface waves (SWs) in seismic records can be used to extract local dispersion curves (DCs) along a seismic line. These curves can be used to estimate near-surface S-wave velocity models. If the velocity models are used to compute S-wave static corrections, the required information consists of S-wave time-average velocities that define the one-way time for a given datum plan depth. However, given the wider use of P-wave reflection seismic with respect to S-wave surveys, the estimate of P-wave time-average velocity would be more useful. We therefore focus on the possibility of also extracting time-average P-wave velocity models from SW dispersion data. We start from a known 1D S-wave velocity model along the line, with its relevant DC, and we estimate a wavelength/depth relationship for SWs. We found that this relationship is sensitive to Poisson’s ratio, and we develop a simple method for estimating an “apparent” Poisson’s ratio profile, defined as the Poisson’s ratio value that relates the time-average S-wave velocity to the time-average P-wave velocity. Hence, we transform the time-average S-wave velocity models estimated from the DCs into the time-average P-wave velocity models along the seismic line. We tested the method on synthetic and field data and found that it is possible to retrieve time-average P-wave velocity models with uncertainties mostly less than 10% in laterally varying sites and one-way traveltime for P-waves with less than 5 ms uncertainty with respect to P-wave tomography data. To our knowledge, this is the first method for reliable estimation of P-wave velocity from SW data without any a priori information or additional data.

Seismic wave velocity investigation at The Geysers‐Clear Lake geothermal field, California

Geophysics ◽  
1982 ◽  
Vol 47 (5) ◽  
pp. 819-824 ◽  
Author(s):  
Harsh K. Gupta ◽  
Ronald W. Ward ◽  
Tzeu‐Lie Lin
Keyword(s):  
Wave Velocity ◽  
Poisson’S Ratio ◽  
Poisson Ratio ◽  
Volcanic Field ◽  
P Wave ◽  
Poisson's Ratio ◽  
Clear Lake ◽  
Seismic Wave Velocity ◽  
S Waves ◽  
The Geysers

Analysis of P‐ and S‐waves from shallow microearthquakes in the vicinity of The Geysers geothermal area, California, recorded by a dense, telemetered seismic array operated by the U.S. Geological Survey (USGS) shows that these phases are easily recognized and traced on record sections to distances of 80 km. Regional average velocities for the upper crust are estimated to be [Formula: see text] and [Formula: see text] for P‐ and S‐waves, respectively. Poisson’s ratio is estimated at 23 locations using Wadati diagrams and is found to vary from 0.13 to 0.32. In general, the Poisson’s ratio is found to be lower at the locations close to the steam production zones at The Geysers and Clear Lake volcanic field to the northeast. The low Poisson ratio corresponds to a decrease in P‐wave velocity in areas of high heat flow. The decrease may be caused by fracturing of the rock and saturation with gas or steam.

scholarly journals A single Rayleigh mode may exist with multiple values of phase-velocity at one frequency

2020 ◽  
Vol 222 (1) ◽  
pp. 582-594
Author(s):  
Thomas Forbriger ◽  
Lingli Gao ◽  
Peter Malischewsky ◽  
Matthias Ohrnberger ◽  
Yudi Pan
Keyword(s):  
Phase Velocity ◽  
Rayleigh Wave ◽  
Half Space ◽  
Wave Velocity ◽  
Poisson’S Ratio ◽  
P Wave ◽  
Poisson's Ratio ◽  
Wave Number ◽  
Homogeneous Layer ◽  
Rayleigh Mode

SUMMARY Other than commonly assumed in seismology, the phase velocity of Rayleigh waves is not necessarily a single-valued function of frequency. In fact, a single Rayleigh mode can exist with three different values of phase velocity at one frequency. We demonstrate this for the first higher mode on a realistic shallow seismic structure of a homogeneous layer of unconsolidated sediments on top of a half-space of solid rock (LOH). In the case of LOH a significant contrast to the half-space is required to produce the phenomenon. In a simpler structure of a homogeneous layer with fixed (rigid) bottom (LFB) the phenomenon exists for values of Poisson’s ratio between 0.19 and 0.5 and is most pronounced for P-wave velocity being three times S-wave velocity (Poisson’s ratio of 0.4375). A pavement-like structure (PAV) of two layers on top of a half-space produces the multivaluedness for the fundamental mode. Programs for the computation of synthetic dispersion curves are prone to trouble in such cases. Many of them use mode-follower algorithms which loose track of the dispersion curve and miss the multivalued section. We show results for well established programs. Their inability to properly handle these cases might be one reason why the phenomenon of multivaluedness went unnoticed in seismological Rayleigh wave research for so long. For the very same reason methods of dispersion analysis must fail if they imply wave number kl(ω) for the lth Rayleigh mode to be a single-valued function of frequency ω. This applies in particular to deconvolution methods like phase-matched filters. We demonstrate that a slant-stack analysis fails in the multivalued section, while a Fourier–Bessel transformation captures the complete Rayleigh-wave signal. Waves of finite bandwidth in the multivalued section propagate with positive group-velocity and negative phase-velocity. Their eigenfunctions appear conventional and contain no conspicuous feature.

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