The original Marmousi model was created by a consortium led by the Institut Français du Pétrole (IFP) in 1988. Since its creation, the model and its acoustic finitedifference synthetic data have been used by hundreds of researchers throughout the world for a multitude of geophysical purposes, and to this day remains one of the most published geophysical data sets. The advancement in computer hardware capabilities since the late 1980s has made it possible to perform a major upgrade to the model and data set, thereby extending the usefulness of the model for, hopefully, some time to come. This paper outlines the creation of an updated and upgraded Marmousi model and data set which we have named Marmousi2. We based the new model on the original Marmousi structure, but extended it in width and depth, and made it fully elastic. We generated high-frequency, high-fidelity, elastic, finite-difference synthetics using a state-of-the-art modeling code made available by Lawrence Livermore National Laboratory as part of a U.S. Department of Energy research project. We simulated streamer, OBC, and VSP multicomponent shot records with offsets up to 15 km. We have found these data suitable for a wide variety of geophysical research including calibration of velocity analysis, seismic migration, AVO analysis, impedance inversion, multiple attenuation, and multicomponent imaging. As part of this project, the Marmousi2 model and data set are available to other researchers throughout the world.

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SPECIAL SECTION: I m a g i n g m i g r a t i o n Imaging complexity in the earth -Case studies with optimized ray tomography AbstractWhen building velocity models for seismic depth imaging, a key tool used in the industry is ray-based tomography. In the past 10 years, the resolution of tomographic solutions has seen a continuous increase because of evolving sophistication in methodologies and technology. A vital issue in the data domain is accuracy and density of residual-moveout picks that are used to derive tomographic velocity-model updates. A new automated method allows for precise tracking of accurate residual moveout on prestack depth-migrated gathers and consequently the fast determination of dense, high-quality traveltime residuals for seismic tomography. Synthetic and real data examples from this method demonstrate the value that accurate information concerning local wave paths inherent in these picks brings to the problem of resolving small-scale velocity anomalies. The determination of such small-scale anomalies ultimately leads to flatter prestack depth-migrated gathers and consequently better-focused structural images.

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SummarySeveral elastic models, both 2-D and 3-D. are being built for use in calculating synthetic elastic seismic data. The models will be made available to the research community, along with the synthetic data that are being calculated from them. These shared models have been proposed or contributed by participants in a collaborative industry, national laboratory. and university research project. The purpose of the modeling is to provide synthetic data to better understand elastic wave propagation and the effects of structural and stratigraphic complexities. The 2-D models are easier to design and change and synthetic calculations can be run relatively quickly in them. It will be possible to alter their layer properties and calculate timelapse data sets from them. Field data will be available to accompany many of the 2-D models. 3-D models are more realistic, but more difficult to design and change. They also require considerably more computing resources to calculate synthetic data from them. A new 3-D model is being designed, and will be used for computing synthetic elastic data.are designing new 2-D and 3-D models that will provide synthetic data suitable for testing and calibration of current elastic and converted wave processing and imaging methods.In the early 199O's, several 2-D and 3-D acoustic seismic models were designed to test acoustic imaging, velocity analysis, and other processing technologies, such as AVO. The 2-D Marmousi model (Versteeg, 1994) and the 3-D SEGEAEG salt model (Aminzadeh et al. 1997) were among the most widely used models. Those models, and the synthetic seismic data computed from them were shared with all interested researchers. That sharing facilitated building up a huge collective pool of understanding of the strengths and weaknesses of processing algorithms, velocity estimation methods, imaging methods, and acquisition designs.This modeling effort intends to make similar contributions to elastic modeling through the use of shared models and synthetic data. Larsen et al. (2001) showed the promise and feasibility of carrying out realistic 3-D elastic calculations in a complex 3-D elastic model (an elastic version of the SEG-EAEG salt structure). Full elastic modeling with realistic modeling parametem requires considerable computing and cannot yet be done routinely. Compromises, such as reducing the size of the model, or reducing the frequency of the computed data, can drastically reduce the computing needed

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