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TitreVelocity model construction, uncertainty evaluation, and two-way travel time to sediment thickness conversion
AuteurLi, Q; Shimeld, J; Dickie, K; Dehler, S; DesRoches, K
Source2013 American Geophysical Union Fall Meeting, abstracts; 2013 p. 1
LiensOnline - En ligne
Année2013
Séries alt.Secteur des sciences de la Terre, Contribution externe 20130256
ÉditeurAmerican Geophysical Union
Réunion2013 American Geophysical Union Fall Meeting; San Francisco; US; décembre 9-13, 2013
Documentlivre
Lang.anglais
Mediaen ligne; numérique
Formatshtml
Sujetsinterpretations sismiques; vitesse des ondes sismiques; sismo-sondages; modèles; analyses du temps de parcours; géophysique
ProgrammePreparation of a submission for an extended continental shelf in the Atlantic and Arctic Oceans under UNCLOS, Délimitation du plateau continental du Canada en vertu de la Convention des Nations Unies sur le droit de la mer (UNCLOS)
Résumé(disponible en anglais seulement)
Sediment thickness determinations play a key role in positioning the most seaward fixed points of the outer limits of continental shelves for coastal states. Seismic reflection surveying is an invaluable technique for estimating the sediment thickness required for the positioning. However, such seismic reflection surveying records the two way travel time (twtt) of vertically incident seismic waves. An accurate seismic velocity model is required for the conversion between twtt and sediment thickness. In this approach, a velocity model is constructed, its uncertainty is evaluated, and twtt is converted to sediment thickness. All of these procedures are programmed for batch and script processing. First, a slowness (the inverse of velocity) function, which is based on the solid sediment compaction theory, is selected and it is fitted using all available velocity observations using the reduced major axis (RMA) method, which can minimize errors from both velocity and depth observations. Second, the velocity uncertainty is estimated using a bootstrapping method by simulating a non-replace re-sampling procedure; thus it is also used in the estimation of sediment thickness uncertainty that is caused by velocity model errors. Moreover, with the constructed velocity model, conversion from sediment depth to twtt is resolved analytically and the conversion from twtt to depth is completed by solving a nonlinear equation with Newton iteration method, having approved convergence efficiency and a predefined accuracy (0.1 m). Finally, all these processes have been implemented in C# and JavaScript for integration with GeoFrame file format (seismic horizon interpretation) or embedded in any document with power batch processing and flexible verification facilities. As an example, publicly available velocity observations in the Labrador Sea region are used in the construction of a velocity model and the evaluation of velocity and sediment thickness uncertainty. The conversion between twtt and sediment thickness, based on the constructed velocity model, is derived and their excellent performance is demonstrated by simulating and comparing with published velocity models in the deep water region of the global oceans.
Résumé(Résumé en langage clair et simple, non publié)
Pour livrer présentation sur les nouvelles recherches pour développer des méthodes de limites extérieures informatiques continentaux pour le programme UNCLOS. Il inclut le module vitesse cnstruction, l'estimation de l'incertitude, le temps sismique et de l'estimation de l'épaisseur des sédiments, et la mise en oeuvre thier et des exemples d'application.
GEOSCAN ID293101