scholarly journals Experimental Study on Petrophysical Properties as a Tool to Identify Pore Fluids in Tight-Rock Reservoirs

2021 ◽  
Vol 9 ◽  
Author(s):  
Rupeng Ma ◽  
Jing Ba ◽  
José Carcione ◽  
Maxim Lebedev ◽  
Changsheng Wang
Keyword(s):  
Wave Velocity ◽  
Poisson’S Ratio ◽  
Velocity Ratio ◽  
Data Distribution ◽  
Poisson's Ratio ◽  
Petrophysical Properties ◽  
Pore Fluids ◽  
S Wave ◽  
Wave Velocities ◽  
Lame Constant

The petrophysical properties can be proper indicators to identify oil and gas reservoirs, since the pore fluids have significant effects on the wave response. We have performed ultrasonic measurements on two sets of tight siltstones and dolomites at partial saturation. P- and S-wave velocities are obtained by the pulse transmission technique, while attenuation is calculated using the centroid-frequency shift and spectral-ratio methods. The fluid sensitivities of different properties (i.e., P- and S-wave velocities, impedances and attenuation, Poisson's ratio, density, and their combinations) are quantitatively analyzed by considering the data distribution, based on the crossplot technique. The result shows that the properties (P- to S-wave velocity and attenuation ratios, Poisson's ratio, and first to second Lamé constant ratio) with high fluid-sensitivity indicators successfully distinguish gas from oil and water, unlike oil from water. Moreover, siltstones and dolomites can be identified on the basis of data distribution areas. Ultrasonic rock-physics templates of the P- to S-wave velocity ratio vs. the product of first Lamé constant with density obtained with a poroelastic model, considering the structural heterogeneity and patchy saturation, are used to predict the saturation and porosity, which are in good agreement with the experimental data at different porosity ranges.

S-wave observations in the Franciscan terrane, central California

1981 ◽  
Vol 71 (6) ◽  
pp. 1863-1874
Author(s):  
Alan R. Levander ◽  
Robert L. Kovach
Keyword(s):  
Wave Velocity ◽  
Upper Mantle ◽  
Poisson’S Ratio ◽  
San Andreas Fault ◽  
Poisson's Ratio ◽  
S Wave ◽  
Central California ◽  
Wave Velocities ◽  
San Andreas ◽  
Pn Velocity

Abstract We have examined S-wave arrivals from local earthquakes at a three-station seismograph array in the Franciscan terrane of the Diablo Range, California. A single crustal S-wave phase is observed with a velocity of 3.30 km/sec. Poisson's ratio calculated for the crust from a composite Wadati diagram is 0.27. Beyond epicentral distances of 90 km we have tentatively identified an Sn phase with a velocity of 4.35 km/sec. Other investigators have reported a Pn velocity of 8.0 km/sec corresponding to an upper mantle Poisson's ratio of 0.29. The 3.30 km/sec crustal S-wave velocity is intermediate in value between crustal S-wave velocities measured in similar terranes 75 km north at Berkeley and 90 km south at Bear Valley, suggesting a NW-SE crustal S-wave velocity gradient east of the San Andreas fault in the Franciscan terrane. This may be indicative of an increase in crustal rigidity from southeast to northwest, possibly associated with the differing levels of seismic activity observed along portions of the San Andreas fault.

Seismic velocities and Poisson’s ratio of shallow unconsolidated sands

Geophysics ◽  
2000 ◽  
Vol 65 (2) ◽  
pp. 559-564 ◽  
Author(s):  
Ran Bachrach ◽  
Jack Dvorkin ◽  
Amos M. Nur
Keyword(s):  
Wave Velocity ◽  
Poisson’S Ratio ◽  
Tangential Component ◽  
Poisson's Ratio ◽  
Contact Theory ◽  
Beach Sand ◽  
Contact Radius ◽  
Seismic Velocities ◽  
S Wave ◽  
Unconsolidated Sands

We determined P- and S-wave velocity depth profiles in shallow, unconsolidated beach sand by analyzing three‐component surface seismic data. P- and S-wave velocity profiles were calculated from traveltime measurements of vertical and tangential component seismograms, respectively. The results reveal two discrepancies between theory and data. Whereas both velocities were found to be proportional to the pressure raised to the power of 1/6, as predicted by the Hertz‐Mindlin contact theory, the actual values of the velocities are less than half of those calculated from this theory. We attribute this discrepancy to the angularity of the sand grains. Assuming that the average radii of curvature at the grain contacts are smaller than the average radii of the grains, we modify the Hertz‐Mindlin theory accordingly. We found that the ratio of the contact radius to the grain radius is about 0.086. The second disparity is between the observed Poisson’s ratio of 0.15 and the theoretical value (0.008 for random pack of quartz spheres). This discrepancy can be reconciled by assuming slip at the grain contacts. Because slip decreases the shearing between grains, Poisson’s ratio increases.

scholarly journals Characterization of hydrocarbon reservoir by pore fluid and lithology using elastic parameters in an x field, Niger delta, Nigeria

2018 ◽  
Vol 6 (2) ◽  
pp. 173
Author(s):  
Akpabio . ◽  
Idara O ◽  
Ojo . ◽  
Odunayo T
Keyword(s):  
Wave Velocity ◽  
Niger Delta ◽  
Poisson’S Ratio ◽  
Velocity Ratio ◽  
Rock Physics ◽  
Pore Fluid ◽  
Poisson's Ratio ◽  
Oil Sand ◽  
Elastic Parameters ◽  
Hydrocarbon Reservoir

Quantitative rock physics analysis was carried out to determine the lithology and pore fluid of a reservoir in the Niger Delta. Density, compressional wave velocity and shear wave velocity logs were used as input to calculate elastic parameters such as velocity ratio, Poisson’s ratio, and Bulk Modulus, after estimating the hydrocarbon reservoir in the X field. The calculated velocity ratio log was used to differentiate between sand, sandstone and shale. Poisson’s ratio and velocity ratio were used delineate pore fluid content; gas sand, oil sand and sandstone formation from cross plot analysis. The reservoir in the field lies ranges from 9050 - 9426.5ft, (2760.25 – 2874.93m), this confirm what is obtained in the Niger Delta Basin. The Net Pay zones show an economical viable reservoir, it Net pay depth is 39 – 73.5ft. The Porosity and Permeability of the reservoirs suggested a productivity hydrocarbon reservoir. The reservoir lies between Gas sands, Oil sands and Brine sands, reservoir 2 and reservoir 3 are oil sand reservoirs while reservoir 1 lies between an oil sand and a brine sand.   

scholarly journals On the Effect of CO2 on Seismic and Ultrasonic Properties: A Novel Shale Experiment

Energies ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 5007
Author(s):  
Stian Rørheim ◽  
Mohammad Hossain Bhuiyan ◽  
Andreas Bauer ◽  
Pierre Rolf Cerasi
Keyword(s):  
Young’S Modulus ◽  
Wave Velocity ◽  
Poisson’S Ratio ◽  
Young's Modulus ◽  
Co2 Storage ◽  
Poisson's Ratio ◽  
Rock Properties ◽  
S Wave ◽  
Velocity Changes ◽  
4D Seismic

Carbon capture and storage (CCS) by geological sequestration comprises a permeable formation (reservoir) for CO2 storage topped by an impermeable formation (caprock). Time-lapse (4D) seismic is used to map CO2 movement in the subsurface: CO2 migration into the caprock might change its properties and thus impact its integrity. Simultaneous forced-oscillation and pulse-transmission measurements are combined to quantify Young’s modulus and Poisson’s ratio as well as P- and S-wave velocity changes in the absence and in the presence of CO2 at constant seismic and ultrasonic frequencies. This combination is the laboratory proxy to 4D seismic because rock properties are monitored over time. It also improves the understanding of frequency-dependent (dispersive) properties needed for comparing in-situ and laboratory measurements. To verify our method, Draupne Shale is monitored during three consecutive fluid exposure phases. This shale appears to be resilient to CO2 exposure as its integrity is neither compromised by notable Young’s modulus and Poisson’s ratio nor P- and S-wave velocity changes. No significant changes in Young’s modulus and Poisson’s ratio seismic dispersion are observed. This absence of notable changes in rock properties is attributed to Draupne being a calcite-poor shale resilient to acidic CO2-bearing brine that may be a suitable candidate for CCS.

P-to-S-wave velocity ratio in organic shales

Geophysics ◽  
2019 ◽  
Vol 84 (6) ◽  
pp. MR205-MR222 ◽  
Author(s):  
Sheyore John Omovie ◽  
John P. Castagna
Keyword(s):  
Wave Velocity ◽  
Pore Space ◽  
Velocity Ratio ◽  
Organic Content ◽  
Theoretical Modeling ◽  
S Wave ◽  
Lower Velocity ◽  
Wave Velocities ◽  
Ultrasonic Measurements

In situ P- and S-wave velocity measurements in a variety of organic-rich shales exhibit P-to-S-wave velocity ratios that are significantly lower than lithologically similar fully brine-saturated shales having low organic content. It has been hypothesized that this drop could be explained by the direct influence of kerogen on the rock frame and/or by the presence of free hydrocarbons in the pore space. The correlation of hydrocarbon saturation with total organic content in situ makes it difficult to separate these possible mechanisms using log data alone. Theoretical bounding equations, using pure kerogen as an end-member component without associated gas, indicate that kerogen reduces the P- and S-wave velocities but does not in general reduce their ratio enough to explain the observed low velocity ratio. The theoretical modeling is consistent with ultrasonic measurements on organic shale core samples that indicate no dependence of velocity ratios on the kerogen volume alone. Sonic log measurements of P- and S-wave velocities in seven organic-rich shale formations deviate significantly (typically more than 5%) from the Greenberg-Castagna empirical brine-saturated shale trend toward lower velocity ratios. In these formations, and on core measurements, Gassmann fluid substitution to 100% brine saturation yields velocity ratios consistent with the Greenberg-Castagna velocity trend for fully brine-saturated shales, despite the high organic content. These sonic and ultrasonic measurements, as well as theoretical modeling, suggest that the velocity ratio reduction in organic shales is best explained by the presence of free hydrocarbons.

scholarly journals An Experimental Study of Velocity-Saturation Relationships in Volcanic Rocks

2015 ◽  
Vol 8 (1) ◽  
pp. 142-152 ◽  
Author(s):  
Zhidi Liu ◽  
Jingzhou Zhao
Keyword(s):  
Wave Velocity ◽  
Water Saturation ◽  
Velocity Ratio ◽  
Volcanic Rocks ◽  
Junggar Basin ◽  
S Wave ◽  
Gas Reservoirs ◽  
Velocity Saturation ◽  
Wave Velocities ◽  
Water Saturated

In this paper, experiments are carried out under different pressures and water saturations using core samples of volcanic rocks from the Junggar Basin in China to understand how water saturation affects P- and S-wave velocities. The results show that water saturated rocks exhibit significantly higher P- and S-wave velocities than gas saturated rocks. In addition, the P- and S-wave velocity ratio declines with increasing water saturation. Furthermore, a P- and S-wave velocity ratio vs. resistivity cross plot is created to identify gas reservoirs in the volcanic rocks in the Junggar Basin.

scholarly journals Evolution and properties of young oceanic crust: constraints from Poisson's ratio

2021 ◽  
Author(s):  
M J Funnell ◽  
A H Robinson ◽  
R W Hobbs ◽  
C Peirce
Keyword(s):  
Oceanic Crust ◽  
Wave Velocity ◽  
Poisson’S Ratio ◽  
Seismic Velocity ◽  
P Wave ◽  
Poisson's Ratio ◽  
Morphological Evidence ◽  
S Wave ◽  
Typical Structure ◽  
Velocity Models

Summary The seismic velocity of the oceanic crust is a function of its physical properties that include its lithology, degree of alteration, and porosity. Variations in these properties are particularly significant in young crust, but also occur with age as it evolves through hydrothermal circulation and is progressively covered with sediment. While such variation may be investigated through P-wave velocity alone, joint analysis with S-wave velocity allows the determination of Poisson's ratio, which provides a more robust insight into the nature of change in these properties. Here we describe the independent modelling of P- and S-wave seismic datasets, acquired along an ∼330 km-long profile traversing new to ∼8 Myr-old oceanic crust formed at the intermediate-spreading Costa Rica Rift (CRR). Despite S-wave data coverage being almost four-times lower than that of the P-wave dataset, both velocity models demonstrate correlations in local variability and a long-wavelength increase in velocity with distance, and thus age, from the ridge axis of up to 0.8 and 0.6 km s−1, respectively. Using the Vp and Vs models to calculate Poisson's ratio (σ), it reveals a typical structure for young oceanic crust, with generally high values in the uppermost crust that decrease to a minimum of 0.24 by 1.0–1.5 km sub-basement, before increasing again throughout the lower crust. The observed upper crustal decrease in σ most likely results from sealing of fractures, which is supported by observations of a significant decrease in porosity with depth (from ∼15 to < 2 per cent) through the dyke sequence in Ocean Drilling Program borehole 504B. High Poisson's ratio (>0.31) is observed throughout the crust of the north flank of the CRR axis and, whilst this falls within the ‘serpentinite’ classification of lithological proxies, morphological evidence of pervasive surface magmatism and limited tectonism suggests, instead, that the cause is porosity in the form of pervasive fracturing and, thus, that this is the dominant control on seismic velocity in the newly formed CRR crust. South of the CRR, the values of Poisson's ratio are representative of more typical oceanic crust, and decrease with increasing distance from the spreading centre, most likely as a result of mineralisation and increased fracture infill. This is supported by borehole observations and modelled 3-D seismic anisotropy. Crustal segments formed during periods of particularly low half-spreading rate (<35 mm yr−1) demonstrate high Poisson's ratio relative to the background, indicating the likely retention of increased porosity and fracturing associated with the greater degrees of tectonism at the time of their formation. Across the south flank of the CRR, we find that the average Poisson's ratio in the upper 1 km of the crust decreases with age by ∼0.0084 Myr−1 prior to the thermal sealing of the crust, suggesting that, to at least ∼7 Myr, advective hydrothermal processes dominate early CRR-generated oceanic crustal evolution, consistent with heat flow measurements.

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.

Large Poisson's ratio and low S-wave velocity within the Japan trench inner wall toe

1980 ◽  
Vol 35 (1-3) ◽  
pp. 129-133 ◽  
Author(s):  
Shozaburo Nagumo ◽  
Junzo Kasahara ◽  
Sadayuki Koresawa
Keyword(s):  
Wave Velocity ◽  
Poisson’S Ratio ◽  
Poisson's Ratio ◽  
Japan Trench ◽  
S Wave
Sign in / Sign up

Export Citation Format

Share Document