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Papers by patrick rasolofosaon
Oil & Gas Science and Technology-revue De L Institut Francais Du Petrole, Sep 1, 1985
ABSTRACT
ISRM International Symposium, 1989
Proceedings, Jun 12, 2017
Elastic wave velocities in rocks are classically measured by two methods, namely first-break pick... more Elastic wave velocities in rocks are classically measured by two methods, namely first-break picking (detection of the onset arrival of the wave and measurement of the first-break velocity Vfb) and phase spectrum method (exploitation of the frequency dependence of the signal phase and measurement of the phase velocity Vphase). Here we propose a method to exploit the deviation between Vfb and Vphase for characterizing rock heterogeneity size. For this we adapt existing asymptotic wave theories in random elastic media in order to deal with viscoelastic media, such as rocks. The adapted theory gives the heterogeneity size as a function of the deviation between the two previous velocities, of pathlength, and of the estimated standard deviation of the velocity fluctuations. The heterogeneity sizes deduced from ultrasound in two heterogeneous rocks compare rather well with independent observations on the same samples using X-ray tomodensitometry. In parallel we check the asymptotic result with finite difference (FD) simulations. The agreement is rather satisfactory, however the systematic increase of the deviation between VFB and Vphase with pathlength predicted by asymptotic theory is observed only at small offsets. Frequency effects, not taken into account by asymptotic theory, could be the cause of disagreement at large offsets.
This book can be considered as a natural continuation of the book entitled 'Acoustics of Porous M... more This book can be considered as a natural continuation of the book entitled 'Acoustics of Porous Media', co-authored by Thierry Bourbié, Olivier Coussy and Bernard Zinszner, and issued by our laboratory in 1986 for the French version, and in 1987 for the English version. However, here the clear guideline is experimentation. In contrast to previous books, all the techniques, from the most conventional (using piezoelectric transducers) to the most recent spaceage methods (as laser ultrasonics) are detailed. Furthermore the book is mainly based on experimental data allowing to select the most appropriate theories for describing elastic wave propagation in rocks. Emphasis on Nonlinear elasticity and Seismic anisotropy are also originality of the book. A part of the book also focuses on the history of the different sub-fields dealt with, having in mind that the knowledge of the history of a field contributes to understanding the field itself. For instance, in spite of the clear anteriority of their work the names of the Persian mathematician, physicist and optics engineer Ibn Sahl, and of the English astronomer and mathematician Thomas Harriot are unfairly not, or rarely, associated with the law of refraction, compared to the names of the Dutch astronomer and mathematician Willebrord Snell van Royen, known as Snellius, and of the French philosopher and writer René Descartes, as detailed in the first chapter.
Society of Exploration Geophysicists eBooks, 1996
IFP Energies nouvelles eBooks, 2014
This book can be considered as a natural continuation of the book entitled 'Acoustics of Porous M... more This book can be considered as a natural continuation of the book entitled 'Acoustics of Porous Media', co-authored by Thierry Bourbié, Olivier Coussy and Bernard Zinszner, and issued by our laboratory in 1986 for the French version, and in 1987 for the English version. However, here the clear guideline is experimentation. In contrast to previous books, all the techniques, from the most conventional (using piezoelectric transducers) to the most recent spaceage methods (as laser ultrasonics) are detailed. Furthermore the book is mainly based on experimental data allowing to select the most appropriate theories for describing elastic wave propagation in rocks. Emphasis on Nonlinear elasticity and Seismic anisotropy are also originality of the book. A part of the book also focuses on the history of the different sub-fields dealt with, having in mind that the knowledge of the history of a field contributes to understanding the field itself. For instance, in spite of the clear anteriority of their work the names of the Persian mathematician, physicist and optics engineer Ibn Sahl, and of the English astronomer and mathematician Thomas Harriot are unfairly not, or rarely, associated with the law of refraction, compared to the names of the Dutch astronomer and mathematician Willebrord Snell van Royen, known as Snellius, and of the French philosopher and writer René Descartes, as detailed in the first chapter.
Proceedings, Jun 1, 2015
The major trends in the relation between seismic anisotropy and compaction/diagenesis in shaly fo... more The major trends in the relation between seismic anisotropy and compaction/diagenesis in shaly formations have been recently analyzed from two databases. Unfortunately many of the data of one of the databases correspond to other lithologies than shales, even in a broad sense, which tends to weaken the reached conclusions. In the present study we re-iterate the analysis on two carefully selected and actualized large databases (typically more than 800 samples). Our results confirm that burial/compaction can be excluded as a major cause of seismic anisotropy in shaly formations. Also clay platelet alignment can explain most of the anisotropy measurements of both databases. As a consequence, burial and/or compaction has generally no first order effect on clay platelet alignment. We suggest that the condition of deposition of the sediments is the major factor for the alignment of the clay platelets. At last, we propose simple plots for straightforwardly quantifying the Orientation Distribution Function coefficients W_200 and W_400 of the clay platelet alignment from the measurement of seismic anisotropy parameters.
Rock Physics Templates (RPT) have been introduced to help non-experts in rock physics for litholo... more Rock Physics Templates (RPT) have been introduced to help non-experts in rock physics for lithology and pore fluid interpretation of sonic log data and elastic inversion results. Here we propose an extension of the approach in order to deal with anisotropy. For this we start with the classical RPT chart, namely crossplot of acoustic impedance Zp and P-wave over S-wave velocity ratio. A third dimension, here an anisotropy coefficient, is reported as isolines. On this initial 3D RPT chart we superimpose as color-coded points interpretation parameters, such as porosity or shaliness. We use this representation for studying chemically compacted shales, idealized as thinly stratified random mix of transversely–isotropic smectite and isotropic illite, our purpose being more to illustrate the value of the representation than to demonstrate relevancy of the model. The interpretation parameters are illite proportion Villite and the Orientation Distribution Function coefficients W200 and W400 of the clay minerals in smectite. Among other results, it clearly appears from the charts, as expected, that increasing illitization tends to stiffen the rock, and as a consequence to increase Zp. Increasing alignment of the clay minerals (mainly by increasing W200) surprisingly tends to decrease the P-wave time processing anisotropy parameter Eta.
The strong nonlinear (NL) elastic behavior of rocks related to the presence of mechanical defects... more The strong nonlinear (NL) elastic behavior of rocks related to the presence of mechanical defects (cracks, microfractures, and grain contacts) is now well established. Another classical result is the anisotropic behavior of rocks due to the spatial order exhibited by the orientation distribution function of heterogeneities (for instance, aligned microfractures, and constituent minerals). Both linear and NL elastic properties of the rock must be affected by this order. The purpose of this paper is to quantify both the linear and the non linear elastic constants of rocks, considered as anisotropic, from ultrasonic velocity measurements on statically pre-stressed samples. The complete set of these constants constitutes the most condensed way to characterize completely the linear and the NL elastic behavior of the rock. Our theoretical predictions of the stress-induced effects on the elastic wave propagation are in good agreement with our unique experimental data. Furthermore, it is also possible to predict the variations of the velocities of any wave type or propagating in an arbitrary direction in a rock sample submitted to an arbitrary (but uniform) static state of stress. All the physically expected symmetry principles are well corroborated by the numerical simulations. (4)
66th EAGE Conference & Exhibition, 2004
Oil & Gas Science and Technology-revue De L Institut Francais Du Petrole, Sep 1, 1998
Oil & Gas Science and Technology-revue De L Institut Francais Du Petrole, 1986
ABSTRACT
2nd EAGE North African/Mediterranean Petroleum & Geosciences Conference & Exhibition, 2005
Oil & Gas Science and Technology-revue De L Institut Francais Du Petrole, Sep 1, 1985
ABSTRACT
ISRM International Symposium, 1989
Proceedings, Jun 12, 2017
Elastic wave velocities in rocks are classically measured by two methods, namely first-break pick... more Elastic wave velocities in rocks are classically measured by two methods, namely first-break picking (detection of the onset arrival of the wave and measurement of the first-break velocity Vfb) and phase spectrum method (exploitation of the frequency dependence of the signal phase and measurement of the phase velocity Vphase). Here we propose a method to exploit the deviation between Vfb and Vphase for characterizing rock heterogeneity size. For this we adapt existing asymptotic wave theories in random elastic media in order to deal with viscoelastic media, such as rocks. The adapted theory gives the heterogeneity size as a function of the deviation between the two previous velocities, of pathlength, and of the estimated standard deviation of the velocity fluctuations. The heterogeneity sizes deduced from ultrasound in two heterogeneous rocks compare rather well with independent observations on the same samples using X-ray tomodensitometry. In parallel we check the asymptotic result with finite difference (FD) simulations. The agreement is rather satisfactory, however the systematic increase of the deviation between VFB and Vphase with pathlength predicted by asymptotic theory is observed only at small offsets. Frequency effects, not taken into account by asymptotic theory, could be the cause of disagreement at large offsets.
This book can be considered as a natural continuation of the book entitled 'Acoustics of Porous M... more This book can be considered as a natural continuation of the book entitled 'Acoustics of Porous Media', co-authored by Thierry Bourbié, Olivier Coussy and Bernard Zinszner, and issued by our laboratory in 1986 for the French version, and in 1987 for the English version. However, here the clear guideline is experimentation. In contrast to previous books, all the techniques, from the most conventional (using piezoelectric transducers) to the most recent spaceage methods (as laser ultrasonics) are detailed. Furthermore the book is mainly based on experimental data allowing to select the most appropriate theories for describing elastic wave propagation in rocks. Emphasis on Nonlinear elasticity and Seismic anisotropy are also originality of the book. A part of the book also focuses on the history of the different sub-fields dealt with, having in mind that the knowledge of the history of a field contributes to understanding the field itself. For instance, in spite of the clear anteriority of their work the names of the Persian mathematician, physicist and optics engineer Ibn Sahl, and of the English astronomer and mathematician Thomas Harriot are unfairly not, or rarely, associated with the law of refraction, compared to the names of the Dutch astronomer and mathematician Willebrord Snell van Royen, known as Snellius, and of the French philosopher and writer René Descartes, as detailed in the first chapter.
Society of Exploration Geophysicists eBooks, 1996
IFP Energies nouvelles eBooks, 2014
This book can be considered as a natural continuation of the book entitled 'Acoustics of Porous M... more This book can be considered as a natural continuation of the book entitled 'Acoustics of Porous Media', co-authored by Thierry Bourbié, Olivier Coussy and Bernard Zinszner, and issued by our laboratory in 1986 for the French version, and in 1987 for the English version. However, here the clear guideline is experimentation. In contrast to previous books, all the techniques, from the most conventional (using piezoelectric transducers) to the most recent spaceage methods (as laser ultrasonics) are detailed. Furthermore the book is mainly based on experimental data allowing to select the most appropriate theories for describing elastic wave propagation in rocks. Emphasis on Nonlinear elasticity and Seismic anisotropy are also originality of the book. A part of the book also focuses on the history of the different sub-fields dealt with, having in mind that the knowledge of the history of a field contributes to understanding the field itself. For instance, in spite of the clear anteriority of their work the names of the Persian mathematician, physicist and optics engineer Ibn Sahl, and of the English astronomer and mathematician Thomas Harriot are unfairly not, or rarely, associated with the law of refraction, compared to the names of the Dutch astronomer and mathematician Willebrord Snell van Royen, known as Snellius, and of the French philosopher and writer René Descartes, as detailed in the first chapter.
Proceedings, Jun 1, 2015
The major trends in the relation between seismic anisotropy and compaction/diagenesis in shaly fo... more The major trends in the relation between seismic anisotropy and compaction/diagenesis in shaly formations have been recently analyzed from two databases. Unfortunately many of the data of one of the databases correspond to other lithologies than shales, even in a broad sense, which tends to weaken the reached conclusions. In the present study we re-iterate the analysis on two carefully selected and actualized large databases (typically more than 800 samples). Our results confirm that burial/compaction can be excluded as a major cause of seismic anisotropy in shaly formations. Also clay platelet alignment can explain most of the anisotropy measurements of both databases. As a consequence, burial and/or compaction has generally no first order effect on clay platelet alignment. We suggest that the condition of deposition of the sediments is the major factor for the alignment of the clay platelets. At last, we propose simple plots for straightforwardly quantifying the Orientation Distribution Function coefficients W_200 and W_400 of the clay platelet alignment from the measurement of seismic anisotropy parameters.
Rock Physics Templates (RPT) have been introduced to help non-experts in rock physics for litholo... more Rock Physics Templates (RPT) have been introduced to help non-experts in rock physics for lithology and pore fluid interpretation of sonic log data and elastic inversion results. Here we propose an extension of the approach in order to deal with anisotropy. For this we start with the classical RPT chart, namely crossplot of acoustic impedance Zp and P-wave over S-wave velocity ratio. A third dimension, here an anisotropy coefficient, is reported as isolines. On this initial 3D RPT chart we superimpose as color-coded points interpretation parameters, such as porosity or shaliness. We use this representation for studying chemically compacted shales, idealized as thinly stratified random mix of transversely–isotropic smectite and isotropic illite, our purpose being more to illustrate the value of the representation than to demonstrate relevancy of the model. The interpretation parameters are illite proportion Villite and the Orientation Distribution Function coefficients W200 and W400 of the clay minerals in smectite. Among other results, it clearly appears from the charts, as expected, that increasing illitization tends to stiffen the rock, and as a consequence to increase Zp. Increasing alignment of the clay minerals (mainly by increasing W200) surprisingly tends to decrease the P-wave time processing anisotropy parameter Eta.
The strong nonlinear (NL) elastic behavior of rocks related to the presence of mechanical defects... more The strong nonlinear (NL) elastic behavior of rocks related to the presence of mechanical defects (cracks, microfractures, and grain contacts) is now well established. Another classical result is the anisotropic behavior of rocks due to the spatial order exhibited by the orientation distribution function of heterogeneities (for instance, aligned microfractures, and constituent minerals). Both linear and NL elastic properties of the rock must be affected by this order. The purpose of this paper is to quantify both the linear and the non linear elastic constants of rocks, considered as anisotropic, from ultrasonic velocity measurements on statically pre-stressed samples. The complete set of these constants constitutes the most condensed way to characterize completely the linear and the NL elastic behavior of the rock. Our theoretical predictions of the stress-induced effects on the elastic wave propagation are in good agreement with our unique experimental data. Furthermore, it is also possible to predict the variations of the velocities of any wave type or propagating in an arbitrary direction in a rock sample submitted to an arbitrary (but uniform) static state of stress. All the physically expected symmetry principles are well corroborated by the numerical simulations. (4)
66th EAGE Conference & Exhibition, 2004
Oil & Gas Science and Technology-revue De L Institut Francais Du Petrole, Sep 1, 1998
Oil & Gas Science and Technology-revue De L Institut Francais Du Petrole, 1986
ABSTRACT
2nd EAGE North African/Mediterranean Petroleum & Geosciences Conference & Exhibition, 2005