Pub Date : 2016-03-22DOI: 10.1142/S0218396X15500150
L. Pascal, E. Piot, G. Casalis
The application of wall acoustic lining is a major factor in the reduction of aircraft engine noise. The extended Helmholtz Resonator (EHR) impedance model is widely used since it is representative of the behavior of realistic liners over a wide range of frequencies. Its application in time domain CAA methods by means of z-transform has been the subject of several papers. In contrast to standard liner modeling in time domain CAA, which consists in imposing a boundary condition modeling both the cavities and the perforated sheet of the liner, an alternative approach involves adding the cavities to the computational domain and imposing a condition between these cavities and the duct domain to model the resistive sheet. However, the original method may not be used for broadband acoustics since it implements an impedance condition with frequency independent resistance. This paper describes an extension of this method to implement the EHR impedance model in a time domain CAA method.
{"title":"A New Implementation of the Extended Helmholtz Resonator Acoustic Liner Impedance Model in Time Domain CAA","authors":"L. Pascal, E. Piot, G. Casalis","doi":"10.1142/S0218396X15500150","DOIUrl":"https://doi.org/10.1142/S0218396X15500150","url":null,"abstract":"The application of wall acoustic lining is a major factor in the reduction of aircraft engine noise. The extended Helmholtz Resonator (EHR) impedance model is widely used since it is representative of the behavior of realistic liners over a wide range of frequencies. Its application in time domain CAA methods by means of z-transform has been the subject of several papers. In contrast to standard liner modeling in time domain CAA, which consists in imposing a boundary condition modeling both the cavities and the perforated sheet of the liner, an alternative approach involves adding the cavities to the computational domain and imposing a condition between these cavities and the duct domain to model the resistive sheet. However, the original method may not be used for broadband acoustics since it implements an impedance condition with frequency independent resistance. This paper describes an extension of this method to implement the EHR impedance model in a time domain CAA method.","PeriodicalId":54860,"journal":{"name":"Journal of Computational Acoustics","volume":"31 8 1","pages":"1550015"},"PeriodicalIF":0.0,"publicationDate":"2016-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1142/S0218396X15500150","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"64076585","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2016-03-22DOI: 10.1142/S0218396X15500186
M. A. B. Souf, M. A. B. Souf, D. Chronopoulos, M. Ichchou, O. Bareille, M. Haddar
A robust model for the prediction of the variability of the vibro-acoustic response is presented in this paper. The dynamic response of composite panels is treated using a Statistical Energy Analysis (SEA) approach. One of the basic input parameters is the propagating flexural wavenumber of the modeled panel. The Wave Finite Element Method (WFEM) is used to investigate the dispersion characteristics of the layered panel. It is based on the evaluation of the mass and the stiffness matrices of a periodic segment of the structure. A polynomial eigenvalue problem is then formed for calculating the wavenumbers and the wave mode shapes. The main novelty in this paper consists in evaluating the influence of the variability of the mechanical parameters of the composite panel on its vibro-acoustic response, that is on its sound transmission loss (STL). This influence is quantified using the generalized polynomial chaos expansion. The efficiency of the approach is exhibited for isotropic and orthotropic panels.
{"title":"On the Variability of the Sound Transmission Loss of Composite Panels Through a Parametric Probabilistic Approach","authors":"M. A. B. Souf, M. A. B. Souf, D. Chronopoulos, M. Ichchou, O. Bareille, M. Haddar","doi":"10.1142/S0218396X15500186","DOIUrl":"https://doi.org/10.1142/S0218396X15500186","url":null,"abstract":"A robust model for the prediction of the variability of the vibro-acoustic response is presented in this paper. The dynamic response of composite panels is treated using a Statistical Energy Analysis (SEA) approach. One of the basic input parameters is the propagating flexural wavenumber of the modeled panel. The Wave Finite Element Method (WFEM) is used to investigate the dispersion characteristics of the layered panel. It is based on the evaluation of the mass and the stiffness matrices of a periodic segment of the structure. A polynomial eigenvalue problem is then formed for calculating the wavenumbers and the wave mode shapes. The main novelty in this paper consists in evaluating the influence of the variability of the mechanical parameters of the composite panel on its vibro-acoustic response, that is on its sound transmission loss (STL). This influence is quantified using the generalized polynomial chaos expansion. The efficiency of the approach is exhibited for isotropic and orthotropic panels.","PeriodicalId":54860,"journal":{"name":"Journal of Computational Acoustics","volume":"24 1","pages":"1550018"},"PeriodicalIF":0.0,"publicationDate":"2016-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1142/S0218396X15500186","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"64076717","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2016-03-22DOI: 10.1142/S0218396X15500162
S. Marburg
The phenomenon of irregular frequencies or spurious modes when solving the Kirchhoff–Helmholtz integral equation has been extensively studied over the last six or seven decades. A class of common methods to overcome this phenomenon uses the linear combination of the Kirchhoff–Helmholtz integral equation and its normal derivative. When solving the Neumann problem, this method is usually referred to as the Burton and Miller method. This method uses a coupling parameter which, theoretically, should be complex with nonvanishing imaginary part. In practice, it is usually chosen proportional or even equal to i/k. A literature review of papers about the Burton and Miller method and its implementations revealed that, in some cases, it is better to use -i/k as coupling parameter. The better choice depends on the specific formulation, in particular, on the harmonic time dependence and on the fundamental solution or Green's function, respectively. Surprisingly, an unexpectedly large number of studies is based on the wrong choice of the sign in the coupling parameter. Herein, it is described which sign of the coupling parameter should be used for different configurations. Furthermore, it will be shown that the wrong sign does not just make the solution process inefficient but can lead to completely wrong results in some cases.
{"title":"The Burton and Miller method: Unlocking another mystery of its coupling parameter","authors":"S. Marburg","doi":"10.1142/S0218396X15500162","DOIUrl":"https://doi.org/10.1142/S0218396X15500162","url":null,"abstract":"The phenomenon of irregular frequencies or spurious modes when solving the Kirchhoff–Helmholtz integral equation has been extensively studied over the last six or seven decades. A class of common methods to overcome this phenomenon uses the linear combination of the Kirchhoff–Helmholtz integral equation and its normal derivative. When solving the Neumann problem, this method is usually referred to as the Burton and Miller method. This method uses a coupling parameter which, theoretically, should be complex with nonvanishing imaginary part. In practice, it is usually chosen proportional or even equal to i/k. A literature review of papers about the Burton and Miller method and its implementations revealed that, in some cases, it is better to use -i/k as coupling parameter. The better choice depends on the specific formulation, in particular, on the harmonic time dependence and on the fundamental solution or Green's function, respectively. Surprisingly, an unexpectedly large number of studies is based on the wrong choice of the sign in the coupling parameter. Herein, it is described which sign of the coupling parameter should be used for different configurations. Furthermore, it will be shown that the wrong sign does not just make the solution process inefficient but can lead to completely wrong results in some cases.","PeriodicalId":54860,"journal":{"name":"Journal of Computational Acoustics","volume":"24 1","pages":"1550016"},"PeriodicalIF":0.0,"publicationDate":"2016-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1142/S0218396X15500162","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"64076627","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2016-03-22DOI: 10.1142/S0218396X15500216
H. Woo, Y. Shin
In this paper, a new third-order approximation model for an acoustic-structure interaction problem is introduced. The new approximation model is designed to be an accurate and a stable model for predicting the response of a submerged structure. The proposed model is obtained by combining two lower order approximation models instead of using an operator matching method. The stability of this model is checked by a modal analysis. Finally, the approximation model is coupled to the spherical shell structure, and its performance is checked by a shock analysis.
{"title":"Analysis of Acoustic-Structure Interaction Using a High-Order Doubly Asymptotic Approximation","authors":"H. Woo, Y. Shin","doi":"10.1142/S0218396X15500216","DOIUrl":"https://doi.org/10.1142/S0218396X15500216","url":null,"abstract":"In this paper, a new third-order approximation model for an acoustic-structure interaction problem is introduced. The new approximation model is designed to be an accurate and a stable model for predicting the response of a submerged structure. The proposed model is obtained by combining two lower order approximation models instead of using an operator matching method. The stability of this model is checked by a modal analysis. Finally, the approximation model is coupled to the spherical shell structure, and its performance is checked by a shock analysis.","PeriodicalId":54860,"journal":{"name":"Journal of Computational Acoustics","volume":"24 1","pages":"1550021"},"PeriodicalIF":0.0,"publicationDate":"2016-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1142/S0218396X15500216","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"64076608","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2016-03-22DOI: 10.1142/S0218396X15500174
M. Y. Ou, G. Lemoine
The scattering of a plane wave incident obliquely upon an infinite poroelastic cylinder immersed in inviscid fluid is investigated in this paper. Convergence analysis of the series expansion of the solutions for various interface conditions is conducted and it provides a priori estimates on number of terms necessary for achieving a desired accuracy. In contrast to the existing results in the literature, we consider viscous pore fluid and arbitrary interface discharge efficiency ηd. Moreover, the approach presented here does not require any restriction on the viscodynamic operator of the poroelastic equations and hence it can handle general cases beyond the dissipation models proposed by Biot and by Johnson, Koplik and Dashen. The back scattering form function is then calculated from the coefficients of the series solution. Numerical results with various incident angles and interface discharge efficiencies are also presented in this paper.
{"title":"Time-harmonic Analytic Solution for an Acoustic Plane Wave Scattering off an Isotropic Poroelastic Cylinder: Convergence and Form Function","authors":"M. Y. Ou, G. Lemoine","doi":"10.1142/S0218396X15500174","DOIUrl":"https://doi.org/10.1142/S0218396X15500174","url":null,"abstract":"The scattering of a plane wave incident obliquely upon an infinite poroelastic cylinder immersed in inviscid fluid is investigated in this paper. Convergence analysis of the series expansion of the solutions for various interface conditions is conducted and it provides a priori estimates on number of terms necessary for achieving a desired accuracy. In contrast to the existing results in the literature, we consider viscous pore fluid and arbitrary interface discharge efficiency ηd. Moreover, the approach presented here does not require any restriction on the viscodynamic operator of the poroelastic equations and hence it can handle general cases beyond the dissipation models proposed by Biot and by Johnson, Koplik and Dashen. The back scattering form function is then calculated from the coefficients of the series solution. Numerical results with various incident angles and interface discharge efficiencies are also presented in this paper.","PeriodicalId":54860,"journal":{"name":"Journal of Computational Acoustics","volume":"24 1","pages":"1550017"},"PeriodicalIF":0.0,"publicationDate":"2016-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1142/S0218396X15500174","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"64076674","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2016-03-22DOI: 10.1142/S0218396X16500077
Sean Reilly, G. Potty, Michael Goodrich
This paper defines a new three-dimensional (3D) Gaussian ray bundling model in geodetic coordinates: latitude, longitude, and altitude. Derivations are provided for 3D refraction, 3D interface reflection, 3D eigenray detection, and a 3D variant of the Comprehensive Acoustic System Simulation (CASS)/Gaussian Ray Bundling (GRAB) model. This approach allows environmental parameters and their derivatives are computed directly in latitude, longitude, and depth directions without reducing the problem to a series of N ×2D Cartesian projections. Our model supports 3D effects such as great circle routes and horizontal refraction in sloped environments. Key test results are included for ray path refraction accuracy using a Munk profile, Gaussian beam projection into the shadow zone for an n2 linear profile, and horizontal refraction from a 3D analytic wedge. Testing to date indicates that this approach has accuracy at least as good as CASS/GRAB, but with improved execution speed benefits for large numbers of target...
{"title":"Computing Acoustic Transmission Loss Using 3D Gaussian Ray Bundles in Geodetic Coordinates","authors":"Sean Reilly, G. Potty, Michael Goodrich","doi":"10.1142/S0218396X16500077","DOIUrl":"https://doi.org/10.1142/S0218396X16500077","url":null,"abstract":"This paper defines a new three-dimensional (3D) Gaussian ray bundling model in geodetic coordinates: latitude, longitude, and altitude. Derivations are provided for 3D refraction, 3D interface reflection, 3D eigenray detection, and a 3D variant of the Comprehensive Acoustic System Simulation (CASS)/Gaussian Ray Bundling (GRAB) model. This approach allows environmental parameters and their derivatives are computed directly in latitude, longitude, and depth directions without reducing the problem to a series of N ×2D Cartesian projections. Our model supports 3D effects such as great circle routes and horizontal refraction in sloped environments. Key test results are included for ray path refraction accuracy using a Munk profile, Gaussian beam projection into the shadow zone for an n2 linear profile, and horizontal refraction from a 3D analytic wedge. Testing to date indicates that this approach has accuracy at least as good as CASS/GRAB, but with improved execution speed benefits for large numbers of target...","PeriodicalId":54860,"journal":{"name":"Journal of Computational Acoustics","volume":"24 1","pages":"1650007"},"PeriodicalIF":0.0,"publicationDate":"2016-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1142/S0218396X16500077","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"64077325","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2016-03-22DOI: 10.1142/S0218396X1650003X
M. Metwally, Hee-Sok Han, H. J. Jeon, S. B. Nam, S. Han, Tae-Seong Kim
Low-intensity focused ultrasound (LIFU) is a new noninvasive brain stimulation technique where ultrasound is applied with low frequency and intensity to focus at a target region within the brain in order to exhibit or inhibit neuronal activity. In applying LIFU to the human brain, the skull is the main barrier due to its well-known high anisotropic mechanical properties which will affect the ultrasound focusing thereby affecting the neuromodulation or brain stimulation. This study aims at investigating the influence of the anisotropic mechanical properties of the skull on ultrasound propagation and focusing in LIFU. In this study, we used 2D finite element (FE) head models incorporating the isotropic and anisotropic properties of the skull. Three kinds of stresses were examined and shown within the skull: namely the normal stress in the direction of wave propagation (x-stress), normal stress in the transverse direction to the wave propagation (y-stress), and shear stress. Our analysis show that although most of the pressure that reaches to the brain is due to the longitudinal wave propagation through the skull, the stress in the transverse direction to the wave propagation direction (y-stress) has the main influence on the pressure profile inside the brain. The results also show that the anisotropic properties of the skull broaden the focal size about 19% and 13% in the longitudinal and transverse directions, respectively more than the case of considering the isotropic properties in the realistic 2D FE head model. The results indicate the importance of considering the anisotropic properties of the skull in practicing LIFU to achieve accurate targeting within the brain.
{"title":"Influence of Skull Anisotropic Mechanical Properties in Low-Intensity Focused Ultrasound","authors":"M. Metwally, Hee-Sok Han, H. J. Jeon, S. B. Nam, S. Han, Tae-Seong Kim","doi":"10.1142/S0218396X1650003X","DOIUrl":"https://doi.org/10.1142/S0218396X1650003X","url":null,"abstract":"Low-intensity focused ultrasound (LIFU) is a new noninvasive brain stimulation technique where ultrasound is applied with low frequency and intensity to focus at a target region within the brain in order to exhibit or inhibit neuronal activity. In applying LIFU to the human brain, the skull is the main barrier due to its well-known high anisotropic mechanical properties which will affect the ultrasound focusing thereby affecting the neuromodulation or brain stimulation. This study aims at investigating the influence of the anisotropic mechanical properties of the skull on ultrasound propagation and focusing in LIFU. In this study, we used 2D finite element (FE) head models incorporating the isotropic and anisotropic properties of the skull. Three kinds of stresses were examined and shown within the skull: namely the normal stress in the direction of wave propagation (x-stress), normal stress in the transverse direction to the wave propagation (y-stress), and shear stress. Our analysis show that although most of the pressure that reaches to the brain is due to the longitudinal wave propagation through the skull, the stress in the transverse direction to the wave propagation direction (y-stress) has the main influence on the pressure profile inside the brain. The results also show that the anisotropic properties of the skull broaden the focal size about 19% and 13% in the longitudinal and transverse directions, respectively more than the case of considering the isotropic properties in the realistic 2D FE head model. The results indicate the importance of considering the anisotropic properties of the skull in practicing LIFU to achieve accurate targeting within the brain.","PeriodicalId":54860,"journal":{"name":"Journal of Computational Acoustics","volume":"24 1","pages":"1650003"},"PeriodicalIF":0.0,"publicationDate":"2016-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1142/S0218396X1650003X","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"64077372","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2015-12-01DOI: 10.1142/S0218396X1540007X
Guolong Liang, Wenbin Zhao, Zhan Fan
Direction of arrival (DOA) estimation is of great interest due to its wide applications in sonar, radar and many other areas. However, the near-field interference is always presented in the received data, which may result in degradation of DOA estimation. An approach which can suppress the near-field interference and preserve the far-field signal desired by using a spatial matrix filter is proposed in this paper and some typical DOA estimation algorithms are adjusted to match the filtered data. Simulation results show that the approach can improve capability of DOA estimation under near-field inference efficiently.
{"title":"Direction of Arrival Estimation Under Near-Field Interference Using Matrix Filter","authors":"Guolong Liang, Wenbin Zhao, Zhan Fan","doi":"10.1142/S0218396X1540007X","DOIUrl":"https://doi.org/10.1142/S0218396X1540007X","url":null,"abstract":"Direction of arrival (DOA) estimation is of great interest due to its wide applications in sonar, radar and many other areas. However, the near-field interference is always presented in the received data, which may result in degradation of DOA estimation. An approach which can suppress the near-field interference and preserve the far-field signal desired by using a spatial matrix filter is proposed in this paper and some typical DOA estimation algorithms are adjusted to match the filtered data. Simulation results show that the approach can improve capability of DOA estimation under near-field inference efficiently.","PeriodicalId":54860,"journal":{"name":"Journal of Computational Acoustics","volume":"23 1","pages":"1540007"},"PeriodicalIF":0.0,"publicationDate":"2015-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1142/S0218396X1540007X","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"64075970","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2015-12-01DOI: 10.1142/S0218396X15400032
S. Ramesh, K. Lim, B. Khoo
The present study involves numerical assessment of two types of boundary elements, namely constant and discontinuous quadratic elements based on a hypersingular Burton and Miller boundary integral formulation to tackle spurious frequencies manifesting in exterior problems. Convergence trends of the two types of boundary element with/without the inclusion of hypersingular formulation were studied for various combinations of boundary conditions and over a wide range of frequencies. The results indicate that discontinuous quadratic elements and constant elements give comparable results, with the quadratic elements being computationally more efficient as they take lesser computational time. Nevertheless, the constant element formulation is easier to implement, and it may be used for solving exterior wave propagation problems.
{"title":"Comparison of Constant and Discontinuous Quadratic Boundary Elements for Exterior Axisymmetric Acoustic-Wave Propagation Problems","authors":"S. Ramesh, K. Lim, B. Khoo","doi":"10.1142/S0218396X15400032","DOIUrl":"https://doi.org/10.1142/S0218396X15400032","url":null,"abstract":"The present study involves numerical assessment of two types of boundary elements, namely constant and discontinuous quadratic elements based on a hypersingular Burton and Miller boundary integral formulation to tackle spurious frequencies manifesting in exterior problems. Convergence trends of the two types of boundary element with/without the inclusion of hypersingular formulation were studied for various combinations of boundary conditions and over a wide range of frequencies. The results indicate that discontinuous quadratic elements and constant elements give comparable results, with the quadratic elements being computationally more efficient as they take lesser computational time. Nevertheless, the constant element formulation is easier to implement, and it may be used for solving exterior wave propagation problems.","PeriodicalId":54860,"journal":{"name":"Journal of Computational Acoustics","volume":"23 1","pages":"1540003"},"PeriodicalIF":0.0,"publicationDate":"2015-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1142/S0218396X15400032","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"64075232","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2015-12-01DOI: 10.1142/S0218396X15400068
Tingting Zhang, Yuefeng Sun, Qifeng Dou, Hanrong Zhang, T. Guo, Xiyuan Cai
Acoustic impedance in carbonates is influenced by factors such as porosity, pore structure/fracture, fluid content, and lithology. Occurrence of moldic and vuggy pores, fractures and other pore structures due to diagenesis in carbonate rocks can greatly complicate the relationships between impedance and porosity. Using a frame flexibility factor (γ) derived from a poroelastic model to characterize pore structure in reservoir rocks, we find that its product with porosity can result in a much better correlation with sonic velocity (Vp = A − B ∗ ϕ ∗ γ) and acoustic impedance (AI = C − D ∗ ϕ ∗ γ), where A, B, C and D is 6.60, 0.03, 18.3 and 0.09, respectively for the deep low-porosity carbonate reservoir studied in this paper. These new relationships can also be useful in improving seismic inversion of ultra-deep hydrocarbon reservoirs in other similar environments.
{"title":"Improving Porosity–Velocity Relationships Using Carbonate Pore Types","authors":"Tingting Zhang, Yuefeng Sun, Qifeng Dou, Hanrong Zhang, T. Guo, Xiyuan Cai","doi":"10.1142/S0218396X15400068","DOIUrl":"https://doi.org/10.1142/S0218396X15400068","url":null,"abstract":"Acoustic impedance in carbonates is influenced by factors such as porosity, pore structure/fracture, fluid content, and lithology. Occurrence of moldic and vuggy pores, fractures and other pore structures due to diagenesis in carbonate rocks can greatly complicate the relationships between impedance and porosity. Using a frame flexibility factor (γ) derived from a poroelastic model to characterize pore structure in reservoir rocks, we find that its product with porosity can result in a much better correlation with sonic velocity (Vp = A − B ∗ ϕ ∗ γ) and acoustic impedance (AI = C − D ∗ ϕ ∗ γ), where A, B, C and D is 6.60, 0.03, 18.3 and 0.09, respectively for the deep low-porosity carbonate reservoir studied in this paper. These new relationships can also be useful in improving seismic inversion of ultra-deep hydrocarbon reservoirs in other similar environments.","PeriodicalId":54860,"journal":{"name":"Journal of Computational Acoustics","volume":"23 1","pages":"1540006"},"PeriodicalIF":0.0,"publicationDate":"2015-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1142/S0218396X15400068","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"64075823","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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