Measurements of attenuation from vertical seismic profiles

Geophysics ◽  
1981 ◽  
Vol 46 (11) ◽  
pp. 1548-1558 ◽  
Author(s):  
Paul S. Hauge
Keyword(s):  
Gulf Coast ◽  
Spectral Ratio ◽  
The Other ◽  
Depth Interval ◽  
Seismic Profiles ◽  
Reference Pulse ◽  
Vertical Seismic Profiles ◽  
West Texas ◽  
A Value ◽  
Resolution Limits

Values of attenuation have been extracted from five detailed velocity surveys. Significant amounts of attenuation are observed in all five wells. Measured values of attenuation vary by a factor of 10, ranging from less than 0.1 to 0.9 dB/wavelength. Correlation of attenuation with lithology is good, considering the resolution limits of the surveys. One of the surveys was performed in West Texas, and the other four were carried out in the Gulf Coast area. The total number of recording depths in each survey varied from 31 to 208, with downhole recordings taken every 10 or 20 ft over key stratigraphic zones. In all five surveys, a monitor geophone was placed near the well to check for source consistency. Our procedure for measuring attenuation involved constructing the spectral ratio between each downhole pulse and one particular reference pulse. A value of cumulative attenuation (CA) was then extracted from each spectral ratio and plotted as a function of geophone depth. This method allowed us to use many measurements in determining the attenuation over each depth interval.

Measurements of attenuation from vertical seismic profiles by iterative modeling

Geophysics ◽  
1985 ◽  
Vol 50 (6) ◽  
pp. 931-949 ◽  
Author(s):  
Michel Dietrich ◽  
Michel Bouchon
Keyword(s):  
Velocity Dispersion ◽  
Synthetic Data ◽  
Layered Media ◽  
Spectral Ratio ◽  
Ratio Method ◽  
Seismic Profiles ◽  
Vertical Seismic Profiles ◽  
Anelastic Attenuation ◽  
Vsp Data ◽  
Intrinsic Dissipation

We present a numerical simulation of vertical seismic profiles (VSP) using the discrete horizontal wavenumber representation of seismic wave fields. The theoretical seismograms are computed in the acoustic case for flat layered media, and they include the effects of absorption and velocity dispersion. A study using the synthetic seismograms was conducted to investigate the accuracy and resolution of attenuation measurements from VSP data. It is shown that in finely layered media estimates of the anelastic attenuation obtained by use of the reduced spectral ratio method are usually inaccurate when the attenuation is measured over a small vertical extent. An iterative method is presented which improves the resolution of the measurements of intrinsic dissipation. This method allows determination for synthetic data of the quality factor over depth intervals of about one wavelength of the dominant seismic frequency.

Seismic Q—Stratigraphy or dissipation

Geophysics ◽  
1982 ◽  
Vol 47 (1) ◽  
pp. 16-24 ◽  
Author(s):  
T. W. Spencer ◽  
J. R. Sonnad ◽  
T. M. Butler
Keyword(s):  
Spatial Resolution ◽  
Critical Distance ◽  
Mean Value ◽  
Depth Interval ◽  
Seismic Profiles ◽  
Vertical Seismic Profiles ◽  
Multiple Measurements ◽  
The Mean ◽  
Anomalous Dissipation ◽  
Nondissipative System

The basic problems encountered in extracting estimates of seismic dissipation from data recorded on vertical seismic profiles are analyzed. Because anomalous dissipation in the subsurface is likely to be associated with conditions or lithologies of limited vertical extent, a knowledge of the factors which influence the spatial resolution of an attenuation measurement is of considerable importance. By introducing a statistical perspective, it is possible to simulate multiple measurements in an inhomogeneous interval and to draw conclusions which apply to an entire class of impedance structures. Theoretical seismograms are analyzed to demonstrate that for small receiver separations neither a single measurement nor the mean value determined from multiple measurements is likely to give a good estimate of the attenuation for an inhomogeneous depth interval. For small receiver separations, the attenuation computed from the amplitude ratios method is much more strongly influenced by the local stratigraphy in the immediate vicinity of the seismometer than by the attenuation in the depth interval between seismometers. As the seismometer separation increases, there is a dramatic decrease in the variability in the attenuation values determined from multiple measurements. A critical distance can be defined which is a measure of the spatial resolution. Beyond the critical distance the mean value approaches a quantity which is the sum of two components: the effective dissipation for an inhomogeneous interval and a stratigraphic term which describes the attenuation in a nondissipative system.

Detection and measure of the shear‐wave birefringence from vertical seismic data: Theory and applications

Geophysics ◽  
1992 ◽  
Vol 57 (11) ◽  
pp. 1463-1481 ◽  
Author(s):  
Frédéric Lefeuvre ◽  
Laurence Nicoletis ◽  
Valérie Ansel ◽  
Christian Cliet
Keyword(s):  
Shear Wave ◽  
Least Squares Method ◽  
Synthetic Data ◽  
Real Data ◽  
Original Method ◽  
Depth Interval ◽  
Seismic Profiles ◽  
Data Set ◽  
Vertical Seismic Profiles ◽  
The Matrix

An original method is presented that allows us to measure the local shear‐wave birefringence properties over any depth interval. It requires the acquisition of two shear‐wave vertical seismic profiles (VSPs), each with different initial polarizations of the shear wave. The method is based on the estimation of a two by two matrix (called the propagator matrix) that represents a linear operator between two states of polarization. No information is required about layering above the zone of interest (in particular, about the weathering zone). If these two states of polarization correspond to the direct downgoing shear wave at two different depths [Formula: see text] and [Formula: see text], the operator represents the transmission properties between the two depths. Under the previous hypothesis, this operator is independent of the source polarization and can be accurately estimated by a least‐squares method in the frequency domain. Physically, this operator is a multicomponent deconvolution, whose column vectors represent the state of polarizations at a depth [Formula: see text] for two linear and mutually perpendicular polarizations at depth [Formula: see text]. This allows for the measurement of the birefringence properties in all azimuthal directions to determine the directions for which a linearly polarized shear‐wave propagates. In addition, the method can be applied to perform the deconvolution of the upgoing wavefield by the downgoing wavefield to obtain a reflection matrix. Then the matrix can be interpreted in terms of anisotropy below the receiver depths (particularly below the well bottom) and in terms of anisotropy of the reflector itself. The proposed method is validated on synthetic data and is applied to real data from the Paris basin. For this particular data set, the birefringence is located in two layers; the first layer consists of unproductive sands and clays while the second one corresponds to a carbonate oil reservoir from the Dogger formation. The natural directions in both layers are very close to the main directions known for the regional stress field. The presence of fractures in the reservoir layer can explain the strong birefringence ratio (>6 percent).

VELOCITY DETERMINATIONS BY MEANS OF REFLECTION PROFILES

Geophysics ◽  
1938 ◽  
Vol 3 (4) ◽  
pp. 295-305 ◽  
Author(s):  
C. H. Green
Keyword(s):  
Gulf Coast ◽  
Velocity Profiles ◽  
The Other ◽  
Surface Velocity ◽  
Velocity Measurements ◽  
Indirect Determination ◽  
Texas Gulf Coast ◽  
West Texas ◽  
Field Area

While the idea of making an indirect determination of average sub‐surface velocities by means of reflection profiles is far from new it is nevertheless considered worth reporting, inasmuch as it has been recently employed with fair success by the writer in areas beyond any wells that could be “shot” for direct velocity measurements. Two examples of such surface velocity profiles are described—one located in the Means Field area of Andrews County, West Texas, and the other about 8 miles south of the Refugio Field, in Refugio County on the Texas Gulf Coast.

Effect of Catfish Bone Paste on the Properties of Steamed Bread

2014 ◽  
Vol 881-883 ◽  
pp. 757-760
Author(s):  
Xiao Qing Ren ◽  
Li Zhen Ma ◽  
Xin Yi He
Keyword(s):  
Weight Loss ◽  
Specific Volume ◽  
Cell Structure ◽  
The Other ◽  
Gas Cell ◽  
A Value ◽  
Crumb Structure ◽  
Steamed Bread ◽  
Different Levels ◽  
Structure Properties

The objective of this study was to examine the effect of different levels of catfish bone paste to flour on the physicochemical, textural and crumb structure properties of steamed bread. Six different levels (0, 1, 3, 5, 7,10 %) of catfish bone paste to flour were used in the formulation of the steamed bread. The results showed that the weight loss and TTA of steamed bread decreased with an increase in the levels of the catfish bone paste. On the other hand, the pH increased with an increase in the levels of the catfish bone paste. The specific volume, hardness, chewiness and gas cell structure in the crumb of steamed bread with catfish bone paste at 5% supplementation level were better. Thus, a value of 5% catfish bone paste was considered a better level for incorporation into the steamed bread.

ON SHALLOW‐HOLE TEMPERATURE MEASUREMENTS—A TEST STUDY IN THE SALTON SEA GEOTHERMAL FIELD

Geophysics ◽  
1977 ◽  
Vol 42 (3) ◽  
pp. 572-583 ◽  
Author(s):  
Tien‐Chang Lee
Keyword(s):  
Numerical Methods ◽  
Ground Surface ◽  
Nonlinear Least Squares ◽  
Geothermal Gradient ◽  
Geothermal Field ◽  
The Other ◽  
Temperature Measurements ◽  
Salton Sea ◽  
Depth Interval ◽  
Average Value

Shallow‐hole (<13 m) temperature measurements made at various depths and/or times may yield reliable values of geothermal gradient and thermal diffusivity if the groundwater table is shallow (a few meters) such that the effect of time‐dependent moisture content and physical properties is negligible. Two numerical methods based on nonlinear least‐squares curve fitting are derived to remove the effect of annual temperature wave at the ground surface. One method can provide information on the gradient and diffusivity as a function of depth while the other gives average value over the depth interval measured. Experiments were carried in six test holes cased with 2 cm OD PVC pipes in the Salton Sea geothermal field. A set of 5 to 7 thermistors was permanently buried inside the individual pipes with dry sand. Consistent gradient determinations have been obtained with both numerical methods from six monthly observations. By linearly extrapolating the depths to the 100°C and 200°C isotherms from the calculated gradients and mean ground temperatures, we have found good agreement with the nearby deep‐well data for four holes. Discrepancy is found for two holes, one of which is located near the field of [Formula: see text] mud volcanoes and the other near the volcanic Red Hill, reflecting complicated local hydrologic conditions.

Effects of Light on Schooling and Feeding of Jack Mackerel, Trachurus symmetricus

1968 ◽  
Vol 25 (2) ◽  
pp. 393-407 ◽  
Author(s):  
John R. Hunter
Keyword(s):  
Motion Picture ◽  
Nearest Neighbor ◽  
Motion Pictures ◽  
Separation Distance ◽  
The Other ◽  
Angular Deviation ◽  
Jack Mackerel ◽  
A Value

Schools of six jack mackerel each were photographed with infrared film at eight levels of luminance and also in darkness. Three indices were used to measure the behavior of the school from motion pictures. Two of the indices, mean distance to nearest neighbor and mean separation distance, were measures of the distances between individuals in a school; the other, mean angular deviation, was a measure of differences in orientation between individuals. A value for each index was calculated for each motion picture frame.From 12.1 to 6 × 10−6 ft-L no differences existed in the angular deviation of the school or in the distances between fish. At 6 × 10−7 ft-L the intervals between fish were much larger than at higher levels of brightness and groups showed little uniformity in their orientation. Below 6 × 10−7 ft-L (darkness) schools were dispersed and the distributions of values of angular deviation were random.The ability of jack mackerel to feed on live adult Artemia was also tested at eight levels of luminance and in darkness. The number of Artemia eaten at 6 × 10−5 ft-L was about half of that eaten at the normal daytime level of 12.1 ft-L. Few Artemia were eaten at 6 × 10−7 ft-L and none in darkness.Comparison of these data with measurements of light in the sea indicated that jack mackerel probably would be able to maintain schools near the surface on a moonless starlit night and that they probably could feed effectively near the surface on a full moonlight night.

274 Comparison of Two Ultrasound Systems for Estimation of Carcass Attributes in Feedlot Steers

2021 ◽  
Vol 99 (Supplement_3) ◽  
pp. 142-143
Author(s):  
Noah P Jesko ◽  
Thomas L Perkins ◽  
Ty E Lawrence ◽  
John Richeson ◽  
Charles Looney
Keyword(s):  
Ultrasound Images ◽  
Marbling Score ◽  
The West ◽  
Live Animal ◽  
West Texas ◽  
Feedlot Steers ◽  
A Value ◽  
Animal Data ◽  
Ribeye Area ◽  
Highly Correlated

Abstract Sixty-eight (68) crossbred steers were evaluated using two real-time, B-mode ultrasound units to estimate final carcass attributes. The cattle were ultrasounded at the West Texas A&M research feedlot (Canyon, Texas) and carcass data was collected at the West Texas A&M Meats Laboratory (Canyon, Texas) or Tyson Fresh Meats (Amarillo, Texas). Objectives of the study were 1) to compare ultrasound live animal data to carcass attributes at harvest 2) to evaluate the performance differences between the ALOKA 500 (ALK) and the EVO ultrasound units All ultrasound images were captured by the same Ultrasound Guidelines Council (UGC) certified technician with images being processed at the UltraInsights Laboratory (Pierce, Colorado). The correlations between 12th rib fat thickness of the carcass (FTC) and ultrasound (FTU) were 0.84 for the ALK and 0.85 for the EVO, with no differences being found between the two units (P = 0.15). Correlations between the 12-13th rib carcass ribeye area (REAC) and ultrasound ribeye area (REAU) were 0.69 for the ALK and 0.66 for the EVO. There was no difference in REAU size between the two units. Carcass marbling score (MS) and ultrasound intramuscular fat (IMFU) correlations were 0.78 for the ALK and 0.84 for the EVO. The IMF data were found to be different between the two units, with the EVO measuring a mean IMFU value of 6.03 and the ALK a value of 5.26 with the change of 0.77 being different (P &lt; 0.01). It is concluded that both ultrasound units performed favorably when predicting FTC and marbling score but were not highly correlated for REAU. It was found that the predictions between the two units on FT and REA were the same, though the EVO was higher on both. The IMFU values between the ALK and EVO were different, with the EVO again predicting higher values.

scholarly journals Lipid composition of the brains of she-goat and castrated goat consumed in Ekiti State, Nigeria

2015 ◽  
Vol 50 (2) ◽  
pp. 153-162 ◽  
Author(s):  
EI Adeyeye ◽  
AJ Adesina
Keyword(s):  
Fatty Acids ◽  
Gas Chromatography ◽  
Fatty Acid Composition ◽  
Fatty Acid ◽  
Linear Correlation ◽  
The Other ◽  
A Value ◽  
Significant Difference ◽  
Value Range ◽  
Goat Brain

The levels of fatty acids, phospholipids and sterols were determined in the brains of she-goat and castrated goat found in Ekiti State, Nigeria by gas chromatography. Results showed that the crude fat levels were 9.98 and 10.2 % in the brains of she-goat and castrated goat respectively. The fatty acid composition of she-goat and castrated goat brain shows that the SFA was 40.6 and 42.7 %, MUFA was 37.1 and 38.7 % and PUFA was 20.9 and 22.3% respectively. The other parameters of she-goat and castrated goat brain were found: PUFA/SFA, 0.490 and 0.548; MUFA/SFA, 0.869 and 0.953; n-6/n-3, 0.775 and 11.7; LA/ALA, 0.876 and 28.0; AA/DGLA, 6.05 and 17.4; EPA/DHA, 1.00 and 5.89 and EPSI (PUFA/MUFA), 0.564 and 0.575 respectively. Phospholipids were present in she-goat and castrated goat with a value range of 2365 and 3047 mg/100g respectively. Among the sterols, only cholesterol was of any significant level with values of 1353 mg/100g (she-goat brain) and 1355 mg/100g (castrated goat brain). Linear correlation at ? = 0.05, df: n-1 showed that no significant difference exists between the crude fats, phospholipids and sterols except in the fatty acids parameters.Bangladesh J. Sci. Ind. Res. 50(2), 153-162, 2015

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