TOTAL POROSITY AND MATRIX PARAMETERS OF CARBONATE ROCKS BASED ON THE ELASTIC WAVE VELOCITY AND DENSITY MEASUREMENTS

2018 ◽  
Vol 473 (473) ◽  
pp. 13-26
Author(s):  
Jadwiga JARZYNA ◽  
Edyta PUSKARCZYK ◽  
Ewa OGÓREK ◽  
Jacek MOTYKA
Keyword(s):  
Elastic Wave ◽  
Elastic Waves ◽  
Total Porosity ◽  
Elastic Wave Velocity ◽  
P Wave ◽  
Reservoir Properties ◽  
Rock Samples ◽  
Additional Information ◽  
Wave Velocities ◽  
Boundary Velocity

The purpose of the research was to find relationship between elastic waves velocities obtained from lab measurements and parameters from hydrogeological research. Measurements were conducted on 73 rock samples originating mostly from Jurassic limestone of the Olkusz area. Additional information about the rock samples was obtained when the elastic wave velocities were compared with reservoir parameters such as porosity, permeability and density. Plots of elastic waves velocities vs. porosity and bulk density vs. porosity gave information about the range of P wave velocities from the boundary velocity to the values when porosity is equal to zero. Matrix velocity and density values were introduced into the formulas used to calculate porosity. Anisotropy analysis was made on the basis of elastic wave velocities measured on cores cut in two perpendicular directions. This allowed for identification of fractures in rocks. Results showed that by comparing various petrophysical parameters it was possible to get better information about reservoir properties of aquifers.

Effective elastic properties of rocks with transversely isotropic background permeated by a set of vertical fracture cluster

Geophysics ◽  
2021 ◽  
pp. 1-78
Author(s):  
Da Shuai ◽  
Alexey Stovas ◽  
Jianxin Wei ◽  
Bangrang Di ◽  
Yang Zhao
Keyword(s):  
Standard Deviation ◽  
Elastic Wave ◽  
Significant Influence ◽  
Transversely Isotropic ◽  
Azimuth Angle ◽  
Effective Medium ◽  
P Wave ◽  
Wave Velocities ◽  
Anisotropy Parameters ◽  
Vertical Fractures

The linear slip theory is gradually being used to characterize seismic anisotropy. If the transversely isotropic medium embeds vertical fractures (VFTI medium), the effective medium becomes orthorhombic. The vertical fractures, in reality, may exist in any azimuth angle which leads the effective medium to be monoclinic. We apply the linear slip theory to create a monoclinic medium by only introducing three more physical meaning parameters: the fracture preferred azimuth angle, the fracture azimuth angle, and the angular standard deviation. First, we summarize the effective compliance of a rock as the sum of the background matrix compliance and the fracture excess compliance. Then, we apply the Bond transformation to rotate the fractures to be azimuth dependent, introduce a Gaussian function to describe the fractures' azimuth distribution assuming that the fractures are statistically distributed around the preferred azimuth angle, and average each fracture excess compliance over azimuth. The numerical examples investigate the influence of the fracture azimuth distribution domain and angular standard deviation on the effective stiffness coefficients, elastic wave velocities, and anisotropy parameters. Our results show that the fracture cluster parameters have a significant influence on the elastic wave velocities. The fracture azimuth distribution domain and angular standard deviation have a bigger influence on the orthorhombic anisotropy parameters in the ( x2, x3) plane than that in the ( x1, x3) plane. The fracture azimuth distribution domain and angular standard deviation have little influence on the monoclinic anisotropy parameters responsible for the P-wave NMO ellipse and have a significant influence on the monoclinic anisotropy parameters responsible for the S1- and S2-wave NMO ellipse. The effective monoclinic can be degenerated into the VFTI medium.

EXTRACTING SUB-SURFACE INFORMATION FROM LONG OFFSET P-WAVE DATA—A CHEAPER ALTERNATIVE TO MULTICOMPONENT OBC FOR EXPLORATION?

2002 ◽  
Vol 42 (1) ◽  
pp. 627
Author(s):  
R.G. Williams ◽  
G. Roberts ◽  
K. Hawkins
Keyword(s):  
Seismic Energy ◽  
Higher Order ◽  
P Wave ◽  
S Wave ◽  
Additional Information ◽  
Wave Data ◽  
Wave Velocities ◽  
Avo Inversion ◽  
Long Offset ◽  
Multicomponent Data

Seismic energy that has been mode converted from pwave to s-wave in the sub-surface may be recorded by multi-component surveys to obtain information about the elastic properties of the earth. Since the energy converted to s-wave is missing from the p-wave an alternative to recording OBC multi-component data is to examine p-wave data for the missing energy. Since pwave velocities are generally faster than s-wave velocities, then for a given reflection point the converted s-wave signal reaches the surface at a shorter offset than the equivalent p-wave information. Thus, it is necessary to record longer offsets for p-wave data than for multicomponent data in order to measure the same information.A non-linear, wide-angle (including post critical) AVO inversion has been developed that allows relative changes in p-wave velocities, s-wave velocities and density to be extracted from long offset p-wave data. To extract amplitudes at long offsets for this inversion it is necessary to image the data correctly, including correcting for higher order moveout and possibly anisotropy if it is present.The higher order moveout may itself be inverted to yield additional information about the anisotropy of the sub-surface.

Petrophysical properties variation of bitumen-bearing carbonates at increasing temperatures from laboratory to model

Geophysics ◽  
2020 ◽  
Vol 85 (5) ◽  
pp. MR297-MR308
Author(s):  
Roberta Ruggieri ◽  
Fabio Trippetta
Keyword(s):  
Central Italy ◽  
Carbonate Reservoir ◽  
P Wave ◽  
Petrophysical Properties ◽  
S Wave ◽  
Reservoir Properties ◽  
Velocity Change ◽  
Seismic Properties ◽  
Wave Velocities ◽  
Velocity Changes

Variations in reservoir seismic properties can be correlated to changes in saturated-fluid properties. Thus, the determination of variation in petrophysical properties of carbonate-bearing rocks is of interest to the oil exploration industry because unconventional oils, such as bitumen (HHC), are emerging as an alternative hydrocarbon reserve. We have investigated the temperature effects on laboratory seismic wave velocities of HHC-bearing carbonate rocks belonging to the Bolognano Formation (Majella Mountain, central Italy), which can be defined as a natural laboratory to study carbonate reservoir properties. We conduct an initial characterization in terms of porosity and density for the carbonate-bearing samples and then density and viscosity measurements for the residual HHC, extracted by HCl dissolution of the hosting rock. Acoustic wave velocities are recorded from ambient temperature to 90°C. Our acoustic velocity data point out an inverse relationship with temperature, and compressional (P) and shear (S) wave velocities show a distinct trend with increasing temperature depending on the amount of HHC content. Indeed, samples with the highest HHC content show a larger gradient of velocity changes in the temperature range of approximately 50°C–60°C, suggesting that the bitumen can be in a fluid state. Conversely, below approximately 50°C, the velocity gradient is lower because, at this temperature, bitumen can change its phase in a solid state. We also propose a theoretical model to predict the P-wave velocity change at different initial porosities for HHC-saturated samples suggesting that the velocity change mainly is related to the absolute volume of HHC.

Incorporating mechanisms of fluid pressure relaxation into inclusion‐based models of elastic wave velocities

Geophysics ◽  
2003 ◽  
Vol 68 (4) ◽  
pp. 1173-1181 ◽  
Author(s):  
S. Richard Taylor ◽  
Rosemary J. Knight
Keyword(s):  
Elastic Wave ◽  
Water Saturation ◽  
Laboratory Data ◽  
Fluid Pressure ◽  
P Wave ◽  
Porous Rocks ◽  
Low Frequencies ◽  
Wave Velocities ◽  
Exact Agreement ◽  
Flow Through

Our new method incorporates fluid pressure communication into inclusion‐based models of elastic wave velocities in porous rocks by defining effective elastic moduli for fluid‐filled inclusions. We illustrate this approach with two models: (1) flow between nearest‐neighbor pairs of inclusions and (2) flow through a network of inclusions that communicates fluid pressure throughout a rock sample. In both models, we assume that pore pressure gradients induce laminar flow through narrow ducts, and we give expressions for the effective bulk moduli of inclusions. We compute P‐wave velocities and attenuation in a model sandstone and illustrate that the dependence on frequency and water‐saturation agrees qualitatively with laboratory data. We consider levels of water saturation from 0 to 100% and all wavelengths much larger than the scale of material heterogeneity, obtaining near‐exact agreement with Gassmann theory at low frequencies and exact agreement with inclusion‐based models at high frequencies.

SEISMIC VELOCITY STUDY OF SYNTHETIC CORES

Geophysics ◽  
1957 ◽  
Vol 22 (4) ◽  
pp. 813-820 ◽  
Author(s):  
William O. Murphy ◽  
Joseph W. Berg ◽  
Kenneth L. Cook
Keyword(s):  
Elastic Wave ◽  
Elastic Waves ◽  
Atmospheric Pressure ◽  
Room Temperature ◽  
Seismic Velocity ◽  
Pore Filling ◽  
The Core ◽  
Wave Velocities ◽  
Longitudinal Elastic Wave ◽  
Alcohol Benzene

The velocity of a longitudinal elastic wave through rock at room temperature and at atmospheric pressure depends upon the nature of the rock frame, the porosity of the rock, and the nature of the pore‐filling fluid. In the present investigation longitudinal elastic wave velocities were measured for sixty synthetic cores. The rock frame consisted of sorted quartz sand grains and cement, the percentage of cement varying from ten to fifty percent. The core porosities varied from 8.8 percent to 22 percent. The velocities were measured for dry air‐filled cores and for cores saturated with various liquids. These pore‐filling liquids were distilled water, ethyl alcohol, benzene, carbon tetrachloride, and chloroform. The measured velocities ranged from 2,360 feet per second to 14,710 feet per second. The wave velocity in liquid‐filled cores of 10 percent porosity was approximately twice the velocity for cores of 20 percent porosity, the same type of cement being used in both instances. For any given core, flooded with fluids of wave velocities ranging from 3,000 to 5,000 feet per second, the maximum observed variation in core velocity was around 20 percent. The experimental data fitted the empirical linear equation [Formula: see text] where [Formula: see text] of longitudinal elastic waves passing through the flooded core; [Formula: see text] of longitudinal elastic waves in passing through the saturating fluid. The constant k depends upon the porosity of the rock and the type of cement used. The constant, C, depends upon the nature of the rock frame.

Comparison of seismic upscaling methods: From sonic to seismic

Geophysics ◽  
2009 ◽  
Vol 74 (2) ◽  
pp. WA3-WA14 ◽  
Author(s):  
Dileep K. Tiwary ◽  
Irina O. Bayuk ◽  
Alexander A. Vikhorev ◽  
Evgeni M. Chesnokov
Keyword(s):  
Elastic Wave ◽  
Pair Correlation ◽  
P Wave ◽  
Frequency Bandwidth ◽  
Frequency Range ◽  
S Wave ◽  
Wave Velocities ◽  
Backus Averaging ◽  
The Difference ◽  
Gas Bearing

The term “upscaling” used here means a prediction of elastic-wave velocities at lower frequencies from the velocities at higher frequencies. Three different methods of upscaling are considered, including the simple averaging, Backus averaging, and pair correlation function methods. These methods are applied to upscale the elastic-wave velocities measured at sonic frequencies ([Formula: see text], logging data) available for a well penetrating layers of gas-bearing shales and carbonates. As a result, a velocity distribution over depth for [Formula: see text] and [Formula: see text] is found in the frequency range of [Formula: see text]. The difference in the results obtained for a particular depth by the three theoretical methods in the surface seismic frequency bandwidth [Formula: see text] is [Formula: see text] for P-wave and [Formula: see text] for S-wave velocity. This difference is attributed to different theoretical backgrounds underlying these methods.

Physical and elastic properties of some khondalites from the Eastern Ghat Belt of Peninsular India

1976 ◽  
Vol 13 (9) ◽  
pp. 1333-1342 ◽  
Author(s):  
B. S. Gogte ◽  
Y. V. Ramana
Keyword(s):  
Elastic Wave ◽  
Manganese Oxide ◽  
Elastic Properties ◽  
Fracture Strength ◽  
Elastic Wave Velocity ◽  
Eastern Ghats ◽  
Peninsular India ◽  
Wave Velocities ◽  
Shear Wave Velocities ◽  
Rock Suite

Khondalites, which form an important rock suite of the Eastern Ghats, are studied for their physical and elastic properties together with their petrology and petrochemistry. Garnetiferous quartzites exhibit compressional and shear wave velocities between 4.9–5.6 km/s and 2–3 km/s; these are higher than garnet sillimanite gneisses, which are between 3.4–5.2 km/s and 1.4–2.6 km/s, respectively. The latter are more anisotropic than the former. Velocity and anisotropy are affected by alteration of garnet and sillimanite in these rocks. The velocities show a decreasing tendency with increasing manganese oxide. Garnetiferous quartzites bear a higher fracture strength than garnet sillimanite gneisses. Elastic wave velocity studies under hydrostatic pres sure to 5 kbar indicate slight changes with increasing pressure; and the absence of kyanite and the presence of cordierite in negligible amounts suggest their formation near the low to intermediate pressure granulite field.

scholarly journals Diffraction of elastic waves by the periodic rigid boundary of a semi-infinite solid

1978 ◽  
Vol 363 (1715) ◽  
pp. 487-502 ◽  
Keyword(s):  
Integral Equation ◽  
Elastic Wave ◽  
Elastic Waves ◽  
Boundary Surface ◽  
P Wave ◽  
Spatial Period ◽  
Rigid Boundary ◽  
Fused Quartz ◽  
Diffraction Of Elastic Waves ◽  
Periodic Profile

The reflexion of an elastic wave by a rigid boundary of a semi-infinite solid with periodic profile is investigated theoretically. The problem is formulated in terms of an integral equation for the traction at a single spatial period of the boundary surface. Numerical results pertaining to the reflexion of either an incident P-wave or an incident SV-wave for a sinusoidal profile are presented. The calculations have been carried out for three different heights of the periodic profile and for two Poisson ratios (those of fused quartz and silver).

EVALUATION OF THE TIME-DEPENDENT CHARACTERISTICS OF GROUTED SAND USING AN ELASTIC WAVE

2008 ◽  
Vol 22 (11) ◽  
pp. 899-904 ◽  
Author(s):  
JOOWON KIM ◽  
KI-IL SONG ◽  
GYE-CHUN CHO ◽  
SEOK-WON LEE
Keyword(s):  
Numerical Modeling ◽  
Elastic Wave ◽  
Elastic Waves ◽  
Experimental Tests ◽  
Time Dependent ◽  
Soft Ground ◽  
Large Section ◽  
Wave Velocities ◽  
Dependent Behavior ◽  
Strength And Stiffness

For a better evaluation of a grouted zone during and after tunnel construction involving weak soil layers, it is necessary to estimate the characteristics of grouted zone effectively. This study suggests a method that can be used for characterizing the time-dependent behavior of pre-reinforced zones around a large section of tunnel in soft ground using elastic waves. Experimental tests were performed to characterize the time-dependent behavior of the pre-reinforced zone. Experimental results show that shear strengths as well as elastic wave velocities increase with the curing time. Thus, shear strength or strength parameters can be uniquely correlated to elastic wave velocities. It is possible to characterize grouted soils around tunnel using elastic waves. Time-dependent strength and stiffness parameters in the experimental tests were applied in a numerical modeling of a large-section tunnel in soft ground, taking into account its construction sequence. According to the results of the numerical modeling, displacement results for fewer than 2~3 days of constant time boundary conditions are nearly identical to the analysis results of the time-dependent condition. The proposed analysis method, which combines experimental and numerical procedures while considering the time-dependent effect of the pre-reinforced zone on the tunnel behavior, will provide a reliable and practical design basis and a means of analysis for large-section tunnels in soft ground.

scholarly journals On three-stage temperature dependence of elastic wave velocities for rocks

2021 ◽  
Vol 18 (3) ◽  
pp. 328-338
Author(s):  
Nianqi Li ◽  
Li-Yun Fu ◽  
Jian Yang ◽  
Tongcheng Han
Keyword(s):  
Elastic Wave ◽  
Temperature Dependence ◽  
Elastic Constants ◽  
Nonlinear Behavior ◽  
P Wave ◽  
Shape Model ◽  
Wave Velocities ◽  
Nonlinear Thermoelasticity ◽  
Velocity Variations ◽  
Shape Curve

Abstract For most rocks, the typical temperature behavior of elastic wave velocities generally features a three-stage nonlinear characteristic that could be expressed by a reverse S-shape curve with two inflexion points. The mechanism regulating the slow-to-fast transition of elastic constants remains elusive. The physics of critical points seems related to the multimineral composition of rocks with differentiated thermodynamic properties. Based on laboratory experiments for several rocks with different levels of heterogeneity in compositions, we conduct theoretical and empirical simulations by nonlinear thermoelasticity methods and a S-shape model, respectively. The classical theory of linear thermoelasticity based on the Taylor expansion of strain energy functions has been widely used for crystals, but suffers from a deficiency in describing thermal-associated velocity variations for rocks as a polycrystal mixture. Current nonlinear thermoelasticity theory describes the third-order temperature dependence of velocity variations by incorporating the fourth-order elastic constants. It improves the description of temperature-induced three-stage velocity variations in rocks, but involves with some divergences around two inflexion points, especially at high temperatures. The S-shape model for empirical simulations demonstrates a more accurate depiction of thermal-associated three-stage variations of P-wave velocities. We investigate the physics of the parameters ${a_1}$ and ${b_1}$ in the S-shape model. These fitting parameters are closely related to thermophysical properties by being proportional to the specific heat and thermal conductivity of rocks. We discuss the mechanism that regulates the slow-to-fast transition in the three-stage nonlinear behavior for various rocks.

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