The P-SV wave reflection coefficients in VTI and HTI media were obtained by approximation of the Jilek(2002a and b)equation in orthotropic anisotropic media.An approximate equation for P-SV wave elastic impedance ca...The P-SV wave reflection coefficients in VTI and HTI media were obtained by approximation of the Jilek(2002a and b)equation in orthotropic anisotropic media.An approximate equation for P-SV wave elastic impedance can be derived from the combination of the new coefficients with S-wave elastic impedance(Duffaut et al.,2000).On this basis, the fluid identification factor in weakly anisotropic media was constructed and used to identify the Castagna and Smith(1994)lithologic combination and achieved good results. Finally,we specifically analyzed the anisotropic parameter impacts P-SV wave elastic impedance and fluid factor trends.展开更多
Layered concrete media with different wave impedance materials under one-dimensional strain are studied by numerical simulation. The four typical prototypes are analyzed,including concrete foam,air,steel plate and con...Layered concrete media with different wave impedance materials under one-dimensional strain are studied by numerical simulation. The four typical prototypes are analyzed,including concrete foam,air,steel plate and concrete as the middle layer,and the upper and lower layers are concrete materials. The propagation characteristics of plane blast wave in the concrete structure are illustrated,including the propagation and attenuation of stress wave across the different interlayers,the wave reflection and transmission at layered interfaces,the peak value of stress in the lower concrete and the total energy distribution in various medium layers. The result shows that the role of soft interlayer in concrete structure is mainly due to its low wave impedance,the waveform of incident wave is changed,the stress wavelength is pull wide,the radial diffusion of energy is enhanced,and the stress amplitude of and the energy input into the third layer are reduced. Meanwhile,it has been also proved that the air interlayer is able to reduce the peak value of explosion wave which is obviously different from that of foamed material. As a result,it should be concerned about stress amplitude and energy in order to get the best protective structure.展开更多
W-Mo composites with different mass fractions of W and Mo were prepared at1473 K by Spark Plasma Sintering technique. The transverse and longitudinal wave velocities of thesamples were accurately measured using the ul...W-Mo composites with different mass fractions of W and Mo were prepared at1473 K by Spark Plasma Sintering technique. The transverse and longitudinal wave velocities of thesamples were accurately measured using the ultrasonic pulse echo overlap method, and the waveimpedance values of the samples were then calculated. The results show that W-Mo system compositesare of nearly full dense and can be regarded as a mechanical mixture system. The ideal mixture modelwas adopted to estimate the wave impedance of W-Mo composites. Comparisons with the experimentaldata demonstrate that the suggested model is sufficiently accurate to predict the wave impedance ofW-Mo composites.展开更多
In order to increase the evaluating precision of mesh reflection wave, the mesh wave impedance (MWI) is extended to the non-uniform mesh in 1-D and 2-D cases for the first time on the basis of the Yee's positional...In order to increase the evaluating precision of mesh reflection wave, the mesh wave impedance (MWI) is extended to the non-uniform mesh in 1-D and 2-D cases for the first time on the basis of the Yee's positional relation for electromagnetic field components. Lots of characteristics are obtained for different mesh sizes and frequencies. Then the reflection coefficient caused by the non-uniform mesh can be calculated according to the theory of equivalent transmission line. By comparing it with that calculated by MWI in the uniform mesh, it is found that the evaluating error can be largely reduced and is in good agreement with that directly computed by FDTD method. And this extension of MWI can be used in the error analysis of complex mesh.展开更多
Based on the measurements of petrological, petrophysical and elastic properties of the samples of different sedimentary facies in the fourth member of Sinian Dengying Formation (Deng 4 Member) in the Sichuan Basin, th...Based on the measurements of petrological, petrophysical and elastic properties of the samples of different sedimentary facies in the fourth member of Sinian Dengying Formation (Deng 4 Member) in the Sichuan Basin, the diagenetic processes of reservoirs of different sedimentary facies and their controls on the petrophysical properties were discussed. The results show that cracks and mineral composition jointly control the petrophysical properties, and both are significantly influenced by sedimentary environment and diagenesis. The microbial dolomite of mound-shoal facies mainly experienced multi-stage dolomitization, penecontemporaneous dissolution, tectonic rupture and hydrothermal/organic acid dissolution processes, giving rise to cracks and dissolved pores. The grannular dolomite of inter-mound-shoal bottomland or dolomitic lagoon facies mainly underwent mechanical compaction, burial dolomitization and tectonic-hydrothermal action, creating cracks and intercrystalline pores. The diagenesis related to crack development increases the pressure- and saturation-dependent effects of samples, leading to significant decrease in the compressional wave impedance and Poisson's ratio. Dolomitization changes the properties of mineral particles, resulting in a Poisson's ratio close to dolomite. The muddy, siliceous and calcareous sediments in the low-energy environment lead to the decrease of impedance and the differential change of Poisson's ratio (significantly increased or decreased). The samples with both cracks and dissolved pores show high P-wave velocity dispersion characteristics, and the P-wave velocity dispersion of samples with only fractures or pores is the lowest.展开更多
In this article,based on the acoustic measurements of core samples obtained from the low to medium porosity and permeability reservoirs in the WXS Depression,the densities and P and S wave velocities of these core sam...In this article,based on the acoustic measurements of core samples obtained from the low to medium porosity and permeability reservoirs in the WXS Depression,the densities and P and S wave velocities of these core samples were obtained.Then based on these data,a series of elastic parameters were computed.From the basic theory and previous pore fluid research results,we derived a new fluid identification factor(F).Using the relative variations,Ag/w and Ao/w,of the elastic parameters between gas and water saturated samples and between oil and water saturated samples,λρ,σHSFIF,Kρ,λρ-2μρ,and F as quantitative indicators,we evaluate the sensitivity of the different fluid identification factors to identify reservoir fluids and validate the effects by crossplots.These confirm that the new fluid identification factor(F) is more sensitive for distinguishing oil and water than the traditional method and is more favorable for fliud identification in low to medium porosity and permeability reservoirs.展开更多
Presently the research based on the accurate seismic imaging methods for surface relief, complex structure, and complicated velocity distributions is of great significance. Reverse-time migration is considered to be o...Presently the research based on the accurate seismic imaging methods for surface relief, complex structure, and complicated velocity distributions is of great significance. Reverse-time migration is considered to be one of highly accurate methods. In this paper, we propose a new non-reflecting recursive algorithm for reverse-time migration by introducing the wave impedance function into the acoustic wave equation and the algorithm for the surface relief case is derived from the coordinate transformation principle. Using the exploding reflector principle and the zero-time imaging condition of poststack reverse- time migration, poststack numerical simulation and reverse-time migration with complex conditions can be realized. The results of synthetic and real data calculations show that the method effectively suppresses unwanted internal reflections and also deals with the seismic imaging problems resulting from surface relief. So, we prove that this method has strong adaptability and practicality.展开更多
Based on FDTD difference expressions and eigenfunctions of Maxwell functions in cylindrical coordinates, mesh wave impedances (MWIs) in 2D and 3D cylindrical coordinates were introduced. Combined with the concept of p...Based on FDTD difference expressions and eigenfunctions of Maxwell functions in cylindrical coordinates, mesh wave impedances (MWIs) in 2D and 3D cylindrical coordinates were introduced. Combined with the concept of perfectly matched layer (PML), MWI PML absorbing boundary condition (ABC) algorithm was deduced in 2D cylindrical coordinates. Numerical experiments were done to investigate the validity of MWI and its application in cylindrical coordinates FDTD algorithm. The results showed that MWI in cylindrical coordinates can be used to accurately calculate the numerical reflection error caused by different mesh increments in non uniform FDTD. MWI can also provide theoretical criterion to define the permitted variable range of mesh dimension. MWI PML ABC is easy to be applied and reduces low numerical reflection, which only causes a little higher reflection error compared with Teixeira's PML.展开更多
Comprehensive inversion of logging and seismic data presented in this paper is a method to improve seismic data resolution. It involves using ample high-frequency information and complete low-frequency information of ...Comprehensive inversion of logging and seismic data presented in this paper is a method to improve seismic data resolution. It involves using ample high-frequency information and complete low-frequency information of known logging to make up for the lack of limited bandwidth of practical seismic recording, obtaining an approximate reflection coefficient sequence (or wave impedance) of high resolution by iterative inversion and providing more reliable seismic evidence for further lithologic interpretation and lateral tracking, correlation and prediction of thin reservoir. The comprehensive inversion can be realized in the following steps: (1) to establish an initial model of higher resolution; (2) to obtain wavelets, and (3) to constrain iterative inversion. The key to this inversion lies in building an initial model. It is assumed from our experience that when the initial model is properly given, iterative inversion can be quickly converged to the ideal result.展开更多
Porous materials can be found in a variety of geophysical and engineering applications.The existence of thermal contact resistance at the interface between bilayered saturated porous strata would result in a significa...Porous materials can be found in a variety of geophysical and engineering applications.The existence of thermal contact resistance at the interface between bilayered saturated porous strata would result in a significant temperature difference at the interface.An attempt is made to study the thermo-hydro-mechanical coupling dynamic response of bilayered saturated porous strata with thermal contact resistance and elastic wave impedance.The corresponding analytical solutions for the dynamic response of bilayered saturated porous strata under a harmonic thermal load are derived by the operator decomposition method,and their rationality is verified by comparing them with existing solutions.The influences of thermal contact resistance,thermal conductivity ratio,and porosity ratio on the dynamic response of bilayered saturated porous strata are systematically investigated.Outcomes disclose that with the increase of thermal contact resistance,the displacement,pore water pressure and stress decrease gradually,and the temperature jump at the interface between two saturated porous strata increases.展开更多
Seismic inversion and basic theory are briefly presented and the main idea of this method is introduced. Both non-linear wave equation inversion technique and Complete Utilization of Samples Information (CUSI) neural ...Seismic inversion and basic theory are briefly presented and the main idea of this method is introduced. Both non-linear wave equation inversion technique and Complete Utilization of Samples Information (CUSI) neural network analysis are used in lithological interpretation in Jibei coal field. The prediction results indicate that this method can provide reliable data for thin coal exploitation and promising area evaluation.展开更多
According to the special geologic conditions of the Damintun (大民屯) sag in the Liaohe (辽河) basin, with a complex structure and rapid lateral change of thin interbeds, the technique of logging-constraint seismi...According to the special geologic conditions of the Damintun (大民屯) sag in the Liaohe (辽河) basin, with a complex structure and rapid lateral change of thin interbeds, the technique of logging-constraint seismic inversion based on prestack high-resolution seismic data was used in the description of oil-gas reservoirs. Reservoir seismic inversion can effectively identify underground complex geologic structures and seismic anomalous reflection volumes and quantitatively predict the distribution of sandstones in space and their variant law in combination with lithologic interpretation. This work studies the wave impedance inversion of high-resolution prestack seismic data, and logging multi-attribute data inversion, and applies these methods to the Damintun sag. As a result, the vertical resolution of reservoir prediction is raised, ability of identifying thin-interbed sand bodies is enhanced, reliability of reservoir prediction is improved, and favorable lithologic traps of this area are further confirmed. These effects are of significance in the exploration of hidden hydrocarbons in this oilfield.展开更多
Considering the thermal contact resistance and elastic wave impedance at the interface,in this paper we theoretically investigate the thermo-hydro-mechanical(THM)coupling dynamic response of bilayered saturated porous...Considering the thermal contact resistance and elastic wave impedance at the interface,in this paper we theoretically investigate the thermo-hydro-mechanical(THM)coupling dynamic response of bilayered saturated porous media.Fractional thermoelastic theory is applied to porous media with imperfect thermal and mechanical contact.The analytical solutions of the dynamic response of the bilayered saturated porous media are obtained in frequency domain.Furthermore,the effects of fractional derivative parameters and thermal contact resistance on the dynamic response of such media are systematically discussed.Results show that the effects of fractional derivative parameters on the dynamic response of bilayered saturated porous media are related to the thermal contact resistance at the interface.With increasing thermal contact resistance,the displacement,pore water pressure,and stress decrease gradually.展开更多
基金sponsored by the National 973 Program(Grant No.2007CB209603)
文摘The P-SV wave reflection coefficients in VTI and HTI media were obtained by approximation of the Jilek(2002a and b)equation in orthotropic anisotropic media.An approximate equation for P-SV wave elastic impedance can be derived from the combination of the new coefficients with S-wave elastic impedance(Duffaut et al.,2000).On this basis, the fluid identification factor in weakly anisotropic media was constructed and used to identify the Castagna and Smith(1994)lithologic combination and achieved good results. Finally,we specifically analyzed the anisotropic parameter impacts P-SV wave elastic impedance and fluid factor trends.
基金sponsored by the National Natural Science Foundation of China (Grant No.11202028,11172071)the project of State Key Laboratory of Explosion Science and Technology,Beijing Institute of Technology (Grant No.QNKT1006)
文摘Layered concrete media with different wave impedance materials under one-dimensional strain are studied by numerical simulation. The four typical prototypes are analyzed,including concrete foam,air,steel plate and concrete as the middle layer,and the upper and lower layers are concrete materials. The propagation characteristics of plane blast wave in the concrete structure are illustrated,including the propagation and attenuation of stress wave across the different interlayers,the wave reflection and transmission at layered interfaces,the peak value of stress in the lower concrete and the total energy distribution in various medium layers. The result shows that the role of soft interlayer in concrete structure is mainly due to its low wave impedance,the waveform of incident wave is changed,the stress wavelength is pull wide,the radial diffusion of energy is enhanced,and the stress amplitude of and the energy input into the third layer are reduced. Meanwhile,it has been also proved that the air interlayer is able to reduce the peak value of explosion wave which is obviously different from that of foamed material. As a result,it should be concerned about stress amplitude and energy in order to get the best protective structure.
基金The research is financially supported by National Natural Science Foundation of China (No. 50171049)China Postdoctoral Science Foundation (No.2003033528)
文摘W-Mo composites with different mass fractions of W and Mo were prepared at1473 K by Spark Plasma Sintering technique. The transverse and longitudinal wave velocities of thesamples were accurately measured using the ultrasonic pulse echo overlap method, and the waveimpedance values of the samples were then calculated. The results show that W-Mo system compositesare of nearly full dense and can be regarded as a mechanical mixture system. The ideal mixture modelwas adopted to estimate the wave impedance of W-Mo composites. Comparisons with the experimentaldata demonstrate that the suggested model is sufficiently accurate to predict the wave impedance ofW-Mo composites.
文摘In order to increase the evaluating precision of mesh reflection wave, the mesh wave impedance (MWI) is extended to the non-uniform mesh in 1-D and 2-D cases for the first time on the basis of the Yee's positional relation for electromagnetic field components. Lots of characteristics are obtained for different mesh sizes and frequencies. Then the reflection coefficient caused by the non-uniform mesh can be calculated according to the theory of equivalent transmission line. By comparing it with that calculated by MWI in the uniform mesh, it is found that the evaluating error can be largely reduced and is in good agreement with that directly computed by FDTD method. And this extension of MWI can be used in the error analysis of complex mesh.
基金Supported by the National Natural Science Foundation of China(41774136)。
文摘Based on the measurements of petrological, petrophysical and elastic properties of the samples of different sedimentary facies in the fourth member of Sinian Dengying Formation (Deng 4 Member) in the Sichuan Basin, the diagenetic processes of reservoirs of different sedimentary facies and their controls on the petrophysical properties were discussed. The results show that cracks and mineral composition jointly control the petrophysical properties, and both are significantly influenced by sedimentary environment and diagenesis. The microbial dolomite of mound-shoal facies mainly experienced multi-stage dolomitization, penecontemporaneous dissolution, tectonic rupture and hydrothermal/organic acid dissolution processes, giving rise to cracks and dissolved pores. The grannular dolomite of inter-mound-shoal bottomland or dolomitic lagoon facies mainly underwent mechanical compaction, burial dolomitization and tectonic-hydrothermal action, creating cracks and intercrystalline pores. The diagenesis related to crack development increases the pressure- and saturation-dependent effects of samples, leading to significant decrease in the compressional wave impedance and Poisson's ratio. Dolomitization changes the properties of mineral particles, resulting in a Poisson's ratio close to dolomite. The muddy, siliceous and calcareous sediments in the low-energy environment lead to the decrease of impedance and the differential change of Poisson's ratio (significantly increased or decreased). The samples with both cracks and dissolved pores show high P-wave velocity dispersion characteristics, and the P-wave velocity dispersion of samples with only fractures or pores is the lowest.
基金supported by the the Key Project of Chinese Ministry of Education (Grant No.109035)the National Natural Science Foundation Key Project (Grant No.40830423)Key Projects of Students Extra-curricular Science and Technology Research Program of Schlumberger (Grant No.SLBX0908)
文摘In this article,based on the acoustic measurements of core samples obtained from the low to medium porosity and permeability reservoirs in the WXS Depression,the densities and P and S wave velocities of these core samples were obtained.Then based on these data,a series of elastic parameters were computed.From the basic theory and previous pore fluid research results,we derived a new fluid identification factor(F).Using the relative variations,Ag/w and Ao/w,of the elastic parameters between gas and water saturated samples and between oil and water saturated samples,λρ,σHSFIF,Kρ,λρ-2μρ,and F as quantitative indicators,we evaluate the sensitivity of the different fluid identification factors to identify reservoir fluids and validate the effects by crossplots.These confirm that the new fluid identification factor(F) is more sensitive for distinguishing oil and water than the traditional method and is more favorable for fliud identification in low to medium porosity and permeability reservoirs.
基金supported by the National Natural Science Foundation of China (Grant No. 40974073)the National 863 Program (Grant No.2007AA060504)the National 973 Program (Grant No. 2007CB209605) and CNPC Geophysical Laboratories
文摘Presently the research based on the accurate seismic imaging methods for surface relief, complex structure, and complicated velocity distributions is of great significance. Reverse-time migration is considered to be one of highly accurate methods. In this paper, we propose a new non-reflecting recursive algorithm for reverse-time migration by introducing the wave impedance function into the acoustic wave equation and the algorithm for the surface relief case is derived from the coordinate transformation principle. Using the exploding reflector principle and the zero-time imaging condition of poststack reverse- time migration, poststack numerical simulation and reverse-time migration with complex conditions can be realized. The results of synthetic and real data calculations show that the method effectively suppresses unwanted internal reflections and also deals with the seismic imaging problems resulting from surface relief. So, we prove that this method has strong adaptability and practicality.
文摘Based on FDTD difference expressions and eigenfunctions of Maxwell functions in cylindrical coordinates, mesh wave impedances (MWIs) in 2D and 3D cylindrical coordinates were introduced. Combined with the concept of perfectly matched layer (PML), MWI PML absorbing boundary condition (ABC) algorithm was deduced in 2D cylindrical coordinates. Numerical experiments were done to investigate the validity of MWI and its application in cylindrical coordinates FDTD algorithm. The results showed that MWI in cylindrical coordinates can be used to accurately calculate the numerical reflection error caused by different mesh increments in non uniform FDTD. MWI can also provide theoretical criterion to define the permitted variable range of mesh dimension. MWI PML ABC is easy to be applied and reduces low numerical reflection, which only causes a little higher reflection error compared with Teixeira's PML.
文摘Comprehensive inversion of logging and seismic data presented in this paper is a method to improve seismic data resolution. It involves using ample high-frequency information and complete low-frequency information of known logging to make up for the lack of limited bandwidth of practical seismic recording, obtaining an approximate reflection coefficient sequence (or wave impedance) of high resolution by iterative inversion and providing more reliable seismic evidence for further lithologic interpretation and lateral tracking, correlation and prediction of thin reservoir. The comprehensive inversion can be realized in the following steps: (1) to establish an initial model of higher resolution; (2) to obtain wavelets, and (3) to constrain iterative inversion. The key to this inversion lies in building an initial model. It is assumed from our experience that when the initial model is properly given, iterative inversion can be quickly converged to the ideal result.
基金Projects(52108347,52178371)supported by the National Natural Science Foundation of ChinaProject(LQ22E080010)supported by the Exploring Youth Project of Zhejiang Natural Science Foundation,China。
文摘Porous materials can be found in a variety of geophysical and engineering applications.The existence of thermal contact resistance at the interface between bilayered saturated porous strata would result in a significant temperature difference at the interface.An attempt is made to study the thermo-hydro-mechanical coupling dynamic response of bilayered saturated porous strata with thermal contact resistance and elastic wave impedance.The corresponding analytical solutions for the dynamic response of bilayered saturated porous strata under a harmonic thermal load are derived by the operator decomposition method,and their rationality is verified by comparing them with existing solutions.The influences of thermal contact resistance,thermal conductivity ratio,and porosity ratio on the dynamic response of bilayered saturated porous strata are systematically investigated.Outcomes disclose that with the increase of thermal contact resistance,the displacement,pore water pressure and stress decrease gradually,and the temperature jump at the interface between two saturated porous strata increases.
文摘Seismic inversion and basic theory are briefly presented and the main idea of this method is introduced. Both non-linear wave equation inversion technique and Complete Utilization of Samples Information (CUSI) neural network analysis are used in lithological interpretation in Jibei coal field. The prediction results indicate that this method can provide reliable data for thin coal exploitation and promising area evaluation.
基金This paper is supported by the Focused Subject Program of Beijing (No. XK104910598).
文摘According to the special geologic conditions of the Damintun (大民屯) sag in the Liaohe (辽河) basin, with a complex structure and rapid lateral change of thin interbeds, the technique of logging-constraint seismic inversion based on prestack high-resolution seismic data was used in the description of oil-gas reservoirs. Reservoir seismic inversion can effectively identify underground complex geologic structures and seismic anomalous reflection volumes and quantitatively predict the distribution of sandstones in space and their variant law in combination with lithologic interpretation. This work studies the wave impedance inversion of high-resolution prestack seismic data, and logging multi-attribute data inversion, and applies these methods to the Damintun sag. As a result, the vertical resolution of reservoir prediction is raised, ability of identifying thin-interbed sand bodies is enhanced, reliability of reservoir prediction is improved, and favorable lithologic traps of this area are further confirmed. These effects are of significance in the exploration of hidden hydrocarbons in this oilfield.
基金Project supported by the National Natural Science Foundation of China(Nos.52108347 and 51779217)the Primary Research and Development Plan of Zhejiang Province(Nos.2019C03120 and 2020C01147),China。
文摘Considering the thermal contact resistance and elastic wave impedance at the interface,in this paper we theoretically investigate the thermo-hydro-mechanical(THM)coupling dynamic response of bilayered saturated porous media.Fractional thermoelastic theory is applied to porous media with imperfect thermal and mechanical contact.The analytical solutions of the dynamic response of the bilayered saturated porous media are obtained in frequency domain.Furthermore,the effects of fractional derivative parameters and thermal contact resistance on the dynamic response of such media are systematically discussed.Results show that the effects of fractional derivative parameters on the dynamic response of bilayered saturated porous media are related to the thermal contact resistance at the interface.With increasing thermal contact resistance,the displacement,pore water pressure,and stress decrease gradually.