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40 results on '"QADROUH, A. N."'

1. Q: A Review

Author

Carcione, José M., Mainardi, Francesco, Qadrouh, Ayman N., Alajmi, Mamdoh, and Ba, Jing

Published
2024
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6. Rock acoustics of diagenesis and cementation

Author

Carcione, José M., Gei, Davide, Picotti, Stefano, Qadrouh, Ayman N., Alajmi, Mamdoh, and Ba, Jing

Subjects
Physics - Geophysics
Abstract

We simulate the effects of diagenesis, cementation and compaction on the elastic properties of shales and sandstones with four different petro-elastical theories and a basin-evolution model, based on constant heating and sedimentation rates. We consider shales composed of clay minerals, mainly smectite and illite, depending on the burial depth, and the pore space is assumed to be saturated with water at hydrostatic conditions. Diagenesis in shale (smectite/illite transformation here) as a function of depth is described by a 5th-order kinetic equation, based on an Arrhenius reaction rate. On the other hand, quartz cementation in sandstones is based on a model that estimates the volume of precipitated quartz cement and the resulting porosity loss from the temperature history, using an equation relating the precipitation rate to temperature. Effective pressure effects (additional compaction) are accounted for by using Athy equation and the Hertz-Mindlin model. The petro-elastic models yield similar seismic velocities, despite the different level of complexity and physics approaches, with increasing density and seismic velocities as a function of depth. The methodology provides a simple procedure to obtain the velocity of shales and sandstones versus temperature and pressure due to the diagenesis-cementation-compaction process.

Published
2021
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22. Mineralogical and geochemical imprints to determine the provenance, depositional environment, and tectonic setting of the Early Silurian source rock of the Qusaiba shale, Saudi Arabia

Author

Qadrouh, Ayman N., primary, Alajmi, Mamdoh S., additional, Alotaibi, Abdulrahman M., additional, Baioumy, Hassan, additional, Almalki, Majed A., additional, Alyousif, Mazen M., additional, Ahmed Salim, Ahmed Mohamed, additional, and Bin Rogaib, Abdulrahman M., additional

Published
2021
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24. Seismic attenuation, normal moveout stretch, and low-frequency shadows underlying bottom simulating reflector events

Author

Carcione, Jose m., Qadrouh, Ayman n., PERROUD, Herve, Gei, Davide, Ba, Jing, Picotti, Stefano, Istituto Nazionale di Geofisica e di Oceanografia Sperimentale (OGS), SAC—KACST, Géosciences Montpellier, Institut national des sciences de l'Univers (INSU - CNRS)-Université de Montpellier (UM)-Université des Antilles (UA)-Centre National de la Recherche Scientifique (CNRS), and Hohai University

Subjects
[SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], low-frequency shadow, [SDE.MCG]Environmental Sciences/Global Changes, Attenuation, NMO stretch, BSR
Abstract

International audience; In many cases, the seismic response of bottom‐simulating reflectors is characterised by low frequencies called “low‐frequency shadow”. Generally, this phenomenon is interpreted as attenuation due to partial saturation with free gas. Actually, this frequency loss may have multiple causes, with a normal moveout stretch as a possible candidate. To analyse this phenomenon, we compute synthetic seismograms by assuming a lossy bottom‐simulating layer, with varying quality factor and thickness, bounded by the upper hydrate‐brine/gas‐brine and lower gas‐brine/brine interfaces. First, we estimate the shift of the centroid frequency of the power spectrum as a function of the travelled distance of the seismic pulse. Then, we perform one‐dimensional numerical experiments to quantify the loss of frequency of the seismic event below the bottom‐simulating reflector as a function of the quality factor of the bottom‐simulating layer and its thickness (due to wave interference). Then, we compute shot gathers to obtain the stacked section, with and without the normal moveout stretch correction and with and without the presence of wave attenuation in the bottom‐simulating layer. The results indicate that the low‐frequency shadow due to the normal moveout stretch is stronger than that due to attenuation and may constitute a false indicator of the presence of gas. In fact, often, the low‐frequency shadow overlies events with higher frequencies, in contradiction with the physics of wave propagation. This is particularly evident when the low‐frequency shadow is so extensive that the presence of high frequencies below cannot be justified by the acquisition geometry.

Published
2018
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28. A tutorial on machine learning with geophysical applications.

Author

QADROUH, A. N., CARCIONE, J. M., ALAJMI, M., and ALYOUSIF, M. M.

Subjects
*MACHINE learning, *GENETIC algorithms, *QUANTUM computing, *COST functions, *SIMULATED annealing, *ARTIFICIAL intelligence, *ALGORITHMS
Abstract

Machine learning (ML) is any predictive algorithm, or a combination of algorithms, that learns from data (that learns from "experience"), and makes predictions without being explicitly coded with a deterministic model. The most immediate example are neural networks, which are trained with data to minimise a cost function and perform predictions. In this work, we present some ML methods, with simple examples to grasp the basic concepts of each algorithm, avoiding formal mathematical complexities. The techniques involved in ML include gradient methods, genetic algorithms, simulated annealing, neural networks, and the novel field of quantum computing as an aid to speed the algorithms. Geophysical examples are given to illustrate practical applications. [ABSTRACT FROM AUTHOR]

Published
2019
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34. Backus and Wyllie Averages for Seismic Attenuation.

Author

Qadrouh, Ayman N., Carcione, José M., Ba, Jing, Gei, Davide, and Salim, Ahmed M.

Subjects
ATTENUATION of seismic waves, SEISMIC wave velocity, PERMEABILITY, POROSITY, VISCOSITY
Abstract

Backus and Wyllie equations are used to obtain average seismic velocities at zero and infinite frequencies, respectively. Here, these equations are generalized to obtain averages of the seismic quality factor (inversely proportional to attenuation). The results indicate that the Wyllie velocity is higher than the corresponding Backus quantity, as expected, since the ray velocity is a high-frequency limit. On the other hand, the Wyllie quality factor is higher than the Backus one, following the velocity trend, i.e., the higher the velocity (the stiffer the medium), the higher the attenuation. Since the quality factor can be related to properties such as porosity, permeability, and fluid viscosity, these averages can be useful for evaluating reservoir properties. [ABSTRACT FROM AUTHOR]

Published
2018
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39. Papillary muscle intervention vs mitral ring annuloplasty in ischemic mitral regurgitation

Author

Micali, Linda R., Qadrouh, Mohammad N., Parise, Orlando, Parise, Gianmarco, Matteucci, Francesco, Jong, Monique, Tetta, Cecilia, Moula, Amalia I., Johnson, Daniel M., Gelsomino, Sandro, Micali, Linda R., Qadrouh, Mohammad N., Parise, Orlando, Parise, Gianmarco, Matteucci, Francesco, Jong, Monique, Tetta, Cecilia, Moula, Amalia I., Johnson, Daniel M., and Gelsomino, Sandro

Abstract

Background and Aims The main pathophysiological factor of chronic ischemic mitral regurgitation (MR) is the outward displacement of the papillary muscles (PMs) leading to leaflet tethering. For this reason, papillary muscle intervention (PMI) in combination with mitral ring annuloplasty (MRA) has recently been introduced into clinical practice to correct this displacement, and to reduce the recurrence of regurgitation. Methods A meta‐analysis was conducted comparing the outcomes of PMI and MRA performed in combination vs MRA performed alone, in terms of MR recurrence and left ventricular reverse remodeling (LVRR). A meta‐regression was carried out to investigate the impact of the type of PMI procedure on the outcomes. Results MR recurrence in patients undergoing both PMI and MRA was lower than in those who only had MRA (log incidence rate ratio, −0.66; lower‐upper limits, −1.13 to 0.20; I2 = 0.0%; p = .44; Egger's test: intercept 0.35 [−0.78 to 1.51]; p = .42). The group with both PMI and MRA and that with only MRA showed a slightly higher reduction in left ventricular diameters (−5.94%; −8.75% to 3.13%,). However, in both groups, LVRR was <10%. No difference was detected between PM relocation/repositioning and papillary muscle approximation in terms of LVRR (p = .33). Conclusions Using PMI and MRA together has a lower MR recurrence than using MRA alone. No significant LVRR was observed between the two groups nor between the PMI techniques employed.

40. Papillary muscle intervention vs mitral ring annuloplasty in ischemic mitral regurgitation

Author

Micali, Linda R., Qadrouh, Mohammad N., Parise, Orlando, Parise, Gianmarco, Matteucci, Francesco, Jong, Monique, Tetta, Cecilia, Moula, Amalia I., Johnson, Daniel M., Gelsomino, Sandro, Micali, Linda R., Qadrouh, Mohammad N., Parise, Orlando, Parise, Gianmarco, Matteucci, Francesco, Jong, Monique, Tetta, Cecilia, Moula, Amalia I., Johnson, Daniel M., and Gelsomino, Sandro

Abstract

Background and Aims The main pathophysiological factor of chronic ischemic mitral regurgitation (MR) is the outward displacement of the papillary muscles (PMs) leading to leaflet tethering. For this reason, papillary muscle intervention (PMI) in combination with mitral ring annuloplasty (MRA) has recently been introduced into clinical practice to correct this displacement, and to reduce the recurrence of regurgitation. Methods A meta‐analysis was conducted comparing the outcomes of PMI and MRA performed in combination vs MRA performed alone, in terms of MR recurrence and left ventricular reverse remodeling (LVRR). A meta‐regression was carried out to investigate the impact of the type of PMI procedure on the outcomes. Results MR recurrence in patients undergoing both PMI and MRA was lower than in those who only had MRA (log incidence rate ratio, −0.66; lower‐upper limits, −1.13 to 0.20; I2 = 0.0%; p = .44; Egger's test: intercept 0.35 [−0.78 to 1.51]; p = .42). The group with both PMI and MRA and that with only MRA showed a slightly higher reduction in left ventricular diameters (−5.94%; −8.75% to 3.13%,). However, in both groups, LVRR was <10%. No difference was detected between PM relocation/repositioning and papillary muscle approximation in terms of LVRR (p = .33). Conclusions Using PMI and MRA together has a lower MR recurrence than using MRA alone. No significant LVRR was observed between the two groups nor between the PMI techniques employed.

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