The objective of this research is comparative analysis of several standard and one new seismic post- and pre-stack inversion methods and Amplitude Variation with Offset (AVO) attribute analysis in application to the CREWES Blackfoot 3D dataset. To prepare the data to the inversion, I start with processing the dataset by using ProMAX software. This processing, in general, includes static and refraction corrections, velocity analysis and stacking the data. The results show good quality images, which are suitable for inversion.<p> Five types of inversion methods are applied to the dataset and compared. Three of these methods produce solutions for the post-stack Acoustic Impedance (AI) and are per-formed by using the industry-standard Hampson-Russell software. The fourth method uses our in-house algorithm called SILC and implemented in IGeoS seismic processing system. In the fifth approach, the pre-stack gathers are inverted for elastic impedance by range-limited stacking of the common-midpoint (CMP) gathers in offsets and/or angles and then performing independent inversion of angle stack. Further, simultaneous inversion is applied to pre-stack seismic data to invert for both the P- and S-wave impedances. These im-pedances are used to extract the Lamé parameters multiplied by density (LMR), and used to extract the ratios between the P- and S-wave velocities. In addition, CMP gathers are used to produce AVO attribute images, which are good indicators of gas reservoirs. Fi-nally, the results of the different inversion techniques are interpreted and correlated with well-log data and used to characterize the reservoir.<p> The different inversion results show clearly the reservoir with its related low im-pedance within the channel. The post-stack inversion gives the best results; in particular, the model-based inversion shows smoothed images of it while SILC provides a different, higher-resolution image. The elastic impedance also gives results similar to the post-stack inversion. Pre-stack inversion and AVO attributes give reasonable results in cross sections near the center of study area. In other areas, performance of pre-stack inversion is poorer, apparently because of reflection aperture limitations.

The objective of this research is comparative analysis of several standard and one new seismic post- and pre-stack inversion methods and Amplitude Variation with Offset (AVO) attribute analysis in application to the CREWES Blackfoot 3D dataset. To prepare the data to the inversion, I start with processing the dataset by using ProMAX software. This processing, in general, includes static and refraction corrections, velocity analysis and stacking the data. The results show good quality images, which are suitable for inversion.<p> Five types of inversion methods are applied to the dataset and compared. Three of these methods produce solutions for the post-stack Acoustic Impedance (AI) and are per-formed by using the industry-standard Hampson-Russell software. The fourth method uses our in-house algorithm called SILC and implemented in IGeoS seismic processing system. In the fifth approach, the pre-stack gathers are inverted for elastic impedance by range-limited stacking of the common-midpoint (CMP) gathers in offsets and/or angles and then performing independent inversion of angle stack. Further, simultaneous inversion is applied to pre-stack seismic data to invert for both the P- and S-wave impedances. These im-pedances are used to extract the Lamé parameters multiplied by density (LMR), and used to extract the ratios between the P- and S-wave velocities. In addition, CMP gathers are used to produce AVO attribute images, which are good indicators of gas reservoirs. Fi-nally, the results of the different inversion techniques are interpreted and correlated with well-log data and used to characterize the reservoir.<p> The different inversion results show clearly the reservoir with its related low im-pedance within the channel. The post-stack inversion gives the best results; in particular, the model-based inversion shows smoothed images of it while SILC provides a different, higher-resolution image. The elastic impedance also gives results similar to the post-stack inversion. Pre-stack inversion and AVO attributes give reasonable results in cross sections near the center of study area. In other areas, performance of pre-stack inversion is poorer, apparently because of reflection aperture limitations.

It is often difficult to quantify the drilling and recompletion potential in producing gas fields, due to large variability in rock quality, well spacing, well completion practices, and the large number of wells involved. Given the marginal nature of many of these fields, it is often prohibitively expensive to conduct conventional reservoir characterization and simulation studies to determine infill potential. There is a need for rapid, cost-efficient technology to evaluate infill potential in gas reservoirs, particularly tight gas reservoirs. Some authors have used moving window statistical methods, which are useful screening tools for identifying potential areas or groups of wells for further study. But the accuracy of the moving window method in very heterogeneous reservoirs is limited, based on the analysis of some authors. This study presents a new simulation-based inversion approach for rapid assessment of infill well potential. It differs from typical simulation inversion applications in that, instead of focusing on small-scale, high-resolution problems, it focuses on large-scale, coarse-resolution studies consisting of hundreds or, potentially thousands, of wells. In an initial application, the method employs well locations, production data, an approximate reservoir description and, accordingly, is able to identify potential areas or groups of wells for infill development quickly and inexpensively. Prediction accuracy can be increased commensurate with reservoir characterization effort, time and costs. Thus, the method provides a consistent basis for transition from screening studies to conventional reservoir studies.The proposed approach is demonstrated to be more accurate than moving window statistical methods in synthetic cases, with comparable analysis times and costs. In a bind validation study of a field case with 40 years of production history, the method was able to accurately predict performance for a group of 19 infill wells.

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Full waveform inversion (FWI) for reflection events is limited by its linearized update requirements given by a process equivalent to migration. Unless the background velocity model is reasonably accurate the resulting gradient can have an inaccurate update direction leading the inversion to converge into what we refer to as local minima of the objective function. In this thesis, I first look into the subject of full model wavenumber to analysis the root of local minima and suggest the possible ways to avoid this problem. And then I analysis the possibility of recovering the corresponding wavenumber components through the existing inversion and migration algorithms. Migration can be taken as a generalized inversion method which mainly retrieves the high wavenumber part of the model. Conventional impedance inversion method gives a mapping relationship between the migration image (high wavenumber) and model parameters (full wavenumber) and thus provides a possible cascade inversion strategy to retrieve the full wavenumber components from seismic data. In the proposed approach, consider a mild lateral variation in the model, I find an analytical Frechet derivation corresponding to the new objective function. In the proposed approach, the gradient is given by the oriented time-domain imaging method. This is independent of the background velocity. Specifically, I apply the oriented time-domain imaging (which depends on the reflection slope instead of a background velocity) on the data residual to obtain the geometrical features of the velocity perturbation. Assuming that density is constant, the conventional 1D impedance inversion method is also applicable for 2D or 3D velocity inversion within the process of FWI. This method is not only capable of inverting for velocity, but it is also capable of retrieving anisotropic parameters relying on linearized representations of the reflection response. To eliminate the cross-talk artifacts between different parameters, I utilize what I consider being an optimal parameterization. To do so, I extend the prestack time-domain migration image in incident angle dimension to incorporate angular dependence needed by the multiparameter inversion. For simple models, this approach provides an efficient and stable way to do full waveform inversion or modified seismic inversion and makes the anisotropic inversion more practical. Results based on synthetic data of isotropic and anisotropic case examples illustrate the benefits and limitations of this method.

We extend an efficient cone beam transform inversion formula, proposed earlier for helices, to a general class of curves. The conditions that describe the class are very natural. Curves C are smooth, without self-intersections, have positive curvature and torsion, do not bend too much in a certain sense, and do not admit lines which are tangent to C at one point and intersect C at another point. A domain U is found where reconstruction is possible with a filtered backprojection type algorithm. Results of numerical experiments demonstrate very good image quality. The algorithm developed is useful for image reconstruction in computerized tomography.

Le domaine de l'aviation est en constante évolution. Les nouveaux avions sont de plus en plus performants, mais de plus en plus bruyants. Plusieurs pays imposent une taxe sur le niveau du bruit d'un avion au décollage. Pour cette raison, un travail continuel est fait afin de réduire l'émission du bruit provenant des moteurs d'avions. Toutefois, cela n'est pas encore suffisant et il y a de la place pour l'amélioration des techniques de réduction du bruit. Ce projet de maîtrise s'inscrit dans le cadre du projet ACOU 1 en collaboration avec le Consortium de recherche et d'innovation en aérospatiale au Québec (CRIAQ) et Pratt&Whitney Canada. L'objectif principal est de développer différentes méthodes de mesure pour déterminer les propriétés des matériaux acoustiques qui se trouvent dans les nacelles pour moteur d'avions. Ces matériaux sont utilisés pour réduire le bruit généré par le moteur d'avion. Un résistivimètre à haut débit a été fabriqué et validé. La validation a été effectuée avec des échantillons de mousses de mélamine et de plaques perforées. Ce résistivimètre permet de mesurer la résistance à l'écoulement des matériaux acoustiques. Une méthode optique a été élaborée pour mesurer le taux de perforation et le diamètre de perforations de plaques perforées ou de "liners" (traitements acoustiques). Les résultats de validation ont été concluants. Une méthode acoustique a été développée pour déterminer le taux de perforation et le nombre de perforations ouvertes. Les mesures ont été faites dans le domaine linéaire et avec des échantillons de plaques perforées. Les valeurs expérimentales sont proches des valeurs théoriques.

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