Low‐frequency tube waves in permeable rocks

Geophysics ◽  
1988 ◽  
Vol 53 (4) ◽  
pp. 519-527 ◽  
Author(s):  
S. K. Chang ◽  
H. L. Liu ◽  
D. L. Johnson
Keyword(s):  
Boundary Conditions ◽  
Explicit Expression ◽  
Low Frequency ◽  
Biot Theory ◽  
Rock Permeability ◽  
Accurate Expression ◽  
Full Solution ◽  
Tube Wave ◽  
Wave Properties

Low‐frequency tube waves in permeable boreholes are of interest because their propagation depends upon in‐situ rock permeability. In this paper, we use low‐ frequency asymptotics to unify two approaches that both describe tube waves. The first approach is due to White, in which the low‐frequency tube‐wave velocity and attenuation are expressed explicitly as functions of frequency. The expressions include contributions from three factors: the borehole fluid compressibility, the wall rigidity, and the wall impedance due to the permeability of the solid. The second approach is the full solution of tube‐wave properties based on Biot theory and the appropriate boundary conditions between the fluid and the porous solid. By taking the low‐frequency approximations to the full solution, we derive an explicit expression for the tube‐wave properties, similar to White’s expression. White’s formulation is hereby corrected to include the elasticity of the solid frame around the borehole. For a 20 cm diameter borehole, the corrected low‐frequency expression is quite accurate below 300 Hz for the four cases shown, when compared with the full solution. Above that frequency, one should use the full solution to obtain an accurate expression of tube‐wave properties in permeable rocks.

Stoneley‐wave attenuation and dispersion in permeable formations

Geophysics ◽  
1989 ◽  
Vol 54 (3) ◽  
pp. 330-341 ◽  
Author(s):  
Andrew N. Norris
Keyword(s):  
Dispersion Relation ◽  
Wave Attenuation ◽  
Low Frequency ◽  
Water Infiltration ◽  
Stoneley Wave ◽  
Biot Theory ◽  
Static Approximation ◽  
Quasi Static Approximation ◽  
Tube Wave ◽  
Dynamic Description

The tube wave, or low‐frequency manifestation of the Stoneley wave, has been modeled previously using the quasi‐static approximation; I extend this method to include the effect of the formation matrix compressibility, which tends to marginally increase the tube‐wave attenuation. Using the Biot theory of poroelasticity, I develop a fully dynamic description of the Stoneley wave. The dispersion relation derived from Biot’s equations reduces in the low‐frequency limit to the quasi‐static dispersion relation. Comparisons of the quasi‐static and dynamic theories for typical sandstones indicate the former to be a good approximation to at least 1 kHz for oil and water infiltration. At higher frequencies, usually between 5 and 20 kHz for the formations considered, a maximum in the Stoneley Q is predicted by the dynamic theory. This phenomenon cannot be explained by the quasi‐static approximation, which predicts a constantly increasing Q with frequency. Instead, the peak in Q may be understood as a transition from dispersion dominated by bore curvature to a higher frequency regime in which the Stoneley wave behaves like a wave on a flat fluid‐porous interface. This hypothesis is supported by analytical and numerical results.

scholarly journals EFFECTS OF BOUNDARY CONDITIONS ON SHAPE FACTOR FOR IN-SITU AIR PERMEABILITY MEASUREMENTS

2009 ◽  
Vol 65 (2) ◽  
pp. 579-586
Author(s):  
Shoichiro HAMAMOTO ◽  
Ken KAWAMOTO ◽  
Masanao NAGAMORI ◽  
Toshiko KOMATSU ◽  
Per MOLDRUP
Keyword(s):  
Boundary Conditions ◽  
Shape Factor ◽  
Air Permeability

Negative Permittivity Behavior in Silver/Polyaniline Metacomposites Induced by the Low-Frequency Plasmonic Oscillation

2021 ◽  
Author(s):  
Jiahong Tian ◽  
Runhua Fan ◽  
Zongxiang Wang ◽  
Jiahao Xin ◽  
Zhongyang Wang
Keyword(s):  
Synthesis Method ◽  
Low Frequency ◽  
In Situ Synthesis ◽  
Negative Permittivity ◽  
Free Electrons ◽  
Dominant Effect ◽  
Equivalent Circuit Analysis ◽  
Inductive Character ◽  
Percolation Network

Abstract Silver/polyaniline (Ag/PANI) composites were prepared by an in-situ synthesis method. Interestingly, the permittivity changed from positive to negative along with the formation of percolation network. The plasma oscillations of free electrons from the network made a dominant effect on the negative permittivity behavior. Further investigation based on equivalent circuit analysis revealed that the composites with negative permittivity presented inductive character. The epsilon-negative composites can be applied to electromagnetic shielding, absorbing and attenuation.

Foreshock wave transmission into the magnetosheath and magnetosphere: results from global hybrid-Vlasov simulations

2021 ◽  
Author(s):  
Lucile Turc ◽  
Markus Battarbee ◽  
Urs Ganse ◽  
Andreas Johlander ◽  
Yann Pfau-Kempf ◽  
...  
Keyword(s):  
Solar Wind ◽  
Mach Number ◽  
Cone Angle ◽  
Low Frequency ◽  
Compressional Wave ◽  
Wave Transmission ◽  
Wave Power ◽  
Solar Wind Flow ◽  
Magnetic Pulsations ◽  
Wave Properties

<p>The foreshock, extending upstream of the quasi-parallel shock and populated with shock-reflected particles, is home to intense wave activity in the ultra-low frequency range.<em> </em>The most commonly observed of these waves are the “30 s” waves, fast magnetosonic waves propagating sunward in the plasma rest frame, but carried earthward by the faster solar wind flow. These waves are thought to be the main source of Pc3 magnetic pulsations (10 – 45 s) in the dayside magnetosphere. A handful of case studies with suitable spacecraft conjunctions have allowed simultaneous investigations of the wave properties in different geophysical regions, but the global picture of the wave transmission from the foreshock through the magnetosheath into the magnetosphere is still not known. In this work, we use global simulations performed with the hybrid-Vlasov model Vlasiator to study the Pc3 wave properties in the foreshock, magnetosheath and magnetosphere for different solar wind conditions. We find that in all three regions the wave power peaks at higher frequencies when the interplanetary magnetic field strength is larger, consistent with previous studies. While the transverse wave power decreases with decreasing Alfvén Mach number in the foreshock, the compressional wave power shows little variation. In contrast, in the magnetosheath and the magnetosphere, the compressional wave power decreases with decreasing Mach number. Inside the magnetosphere, the distribution of wave power varies with the IMF cone angle. We discuss the implications of these results for the propagation of foreshock waves across the different geophysical regions, and in particular their transmission through the bow shock.</p>

Application of Low-Frequency Energy Increment Technology in Hydrocarbon Prediction

2012 ◽  
Vol 472-475 ◽  
pp. 178-182
Author(s):  
Zhi Ming Li ◽  
Xue Yan Hu ◽  
Ling Xia Zhen
Keyword(s):  
Laboratory Data ◽  
Low Frequency ◽  
Biot Theory ◽  
Hydrocarbon Detection ◽  
Hydrocarbon Prediction ◽  
Phase Medium ◽  
Multi Phase ◽  
Cave Detection ◽  
Fluid Detection ◽  
Energy Increment

Based on the Biot theory and laboratory data, engineers of LandOcean recently develop a certain technology for hydrocarbon detection in multi-phase medium in order to reduce ambiguity and uncertainty. The sensitivity of the technology is superior to others especially in carbonate pores and cave detection, igneous hydrocarbon prediction and fluid detection of non-well areas. A number of projects and wells drilling proved that this technology is effective and reliable.

Research on the dynamic characteristic of semi-active hydraulic damping strut

2019 ◽  
Vol 234 (6) ◽  
pp. 1779-1791 ◽  
Author(s):  
Daoyong Wang ◽  
Wencan Zhang ◽  
Mu Chai ◽  
Xiaguang Zeng
Keyword(s):  
Degrees Of Freedom ◽  
Dynamic Stiffness ◽  
Low Frequency ◽  
Maxwell Model ◽  
Friction Model ◽  
Damping Capacity ◽  
Frequency Range ◽  
Stiffness Model ◽  
Rubber Bushing

To reduce the vibration and shock of powertrain in the process of engine key on/off and vehicle in situ shift, a novel semi-active hydraulic damping strut is developed. The purpose of this paper is to study and discuss the dynamic stiffness model of the semi-active hydraulic damping strut. In this study, the dynamic characteristics of semi-active hydraulic damping strut were analyzed based on MTS 831 test rig first. Then, the dynamic stiffness model of semi-active hydraulic damping strut was established based on 2 degrees of freedom vibration system. In this research, a linear, fractional derivative and friction model was used to represent the nonlinear rubber bushing characteristic; the Maxwell model was used to describe the semi-active hydraulic damping strut body model; and the parameters of rubber bushing and semi-active hydraulic damping strut body were identified. The dynamic stiffness values were calculated with solenoid valve energized and not energized at amplitudes of 1 mm and 4 mm, which were consistent with experimental results in low-frequency range. Furthermore, the simplified dynamic stiffness model of the semi-active hydraulic damping strut was discussed, which showed that bushing can be ignored in low-frequency range. Then, the influence of equivalent spring stiffness, damping constant, and rubber bushing stiffness on the stiffness and damping capacity of the semi-active hydraulic damping strut were analyzed. Finally, the prototype of the semi-active hydraulic damping strut was developed and designed based on the vehicle in situ shift and engine key on/off situations, and experiments of the vehicle with and without semi-active hydraulic damping strut were carried out to verify its function.

Early Detection of Relapse by Hypermetaphase Fluorescence In Situ Hybridization After Allogeneic Bone Marrow Transplantation for Chronic Myeloid Leukemia

2000 ◽  
Vol 18 (9) ◽  
pp. 1831-1836 ◽  
Author(s):  
Chy-Myong Seong ◽  
Sergio Giralt ◽  
Hagop Kantarjian ◽  
Jingping Xu ◽  
Jolynn Swantkowski ◽  
...  
Keyword(s):  
Bone Marrow ◽  
In Situ Hybridization ◽  
Fluorescence In Situ Hybridization ◽  
Low Frequency ◽  
Allogeneic Bone Marrow ◽  
Myelogenous Leukemia ◽  
Mixed Chimerism ◽  
Allogeneic Bone ◽  
Time Points

PURPOSE: Standard G-band cytogenetic analysis (CG) provides information on approximately 25 metaphases for monitoring the presence of Philadelphia chromosome positive (Ph+) cells in chronic myelogenous leukemia (CML) patients, making the detection of a low frequency of Ph+ cells problematic. The purpose of this study was to improve the detection of a low frequency of Ph+ cells. PATIENTS AND METHODS: We combined fluorescence in situ hybridization (FISH) with long-term colcemid exposure, capturing several hundred metaphases in bone marrow cultures (hypermetaphase FISH [HMF]). Using probes that identify Ph+ cells, HMF was compared with CG analysis in the follow-up evaluations of 51 patients with CML at various time points after allogeneic bone marrow transplant (BMT). RESULTS: Thirty-five patients never showed the presence of Ph+ cells by either method. In four patients, high frequencies of Ph+ cells were detected by both methods. In the remaining 12 patients, Ph+ cells were detected by HMF at time points after BMT when they were not detected by CG. In seven of the 12 patients, low but statistically significant frequencies of Ph+ cells (0.37% to 5.20%) were detected 3 months or later after BMT, and when no intervention was initiated, all seven patients later relapsed. Based on those data, an eighth patient with mixed chimerism and a similar HMF-detected Ph+ frequency (1.8% at 27 months after BMT) was reinfused with donor lymphocytes and achieved remission with 0% Ph+ cells studied by HMF (up to 50 months after BMT). Ph+ cells detected by HMF but not by CG less than 3 months after BMT disappeared on later examination in two of four patients. After detection of Ph+ cells by HMF only, the median time to cytogenetic progression (detection of Ph+ cells by CG) was 101 days. CONCLUSION: The results demonstrate the ability of HMF to detect low but clinically relevant levels of leukemic cells not detected by CG in transplant patients. The data indicate that HMF can detect low levels of Ph+ cells before standard cytogenetics at a time that may be useful in monitoring disease status and planning clinical interventions.

Local and global fluid-flow effects on dipole flexural waves

Geophysics ◽  
2020 ◽  
Vol 85 (1) ◽  
pp. D1-D11
Author(s):  
Elliot J. H. Dahl ◽  
Kyle T. Spikes
Keyword(s):  
Fluid Flow ◽  
Low Frequency ◽  
Summation Method ◽  
Sensitivity Analyses ◽  
Flexural Wave ◽  
Biot Theory ◽  
S Wave ◽  
Local Flow ◽  
Flow Effects ◽  
Wave Induced

Wave-induced fluid flow (WIFF) can significantly alter the effective formation velocities and cause increasing waveform dispersion and attenuation. We have used modified frame moduli from the theory of Chapman together with the classic Biot theory to improve the understanding of local- and global-flow effects on dipole flexural wave modes in boreholes. We investigate slow and fast formations with and without compliant pores, which induce local flow. The discrete wavenumber summation method generates the waveforms, which are then processed with the weighted spectral semblance method to compare with the solution of the period equation. We find compliant pores to decrease the resulting effective formation P- and S-wave velocities, that in turn decrease the low-frequency velocity limit of the flexural wave. Furthermore, depending on the frequency at which the local-flow dispersion occurs, different S-wave velocity predictions from the flexural wave become possible. This issue is investigated through changing the local-flow critical frequency. Sensitivity analyses of the flexural-wave phase velocity to small changes in WIFF parameters indicate the modeling to be mostly sensitive to compliant pores in slow and fast formations.

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