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| A method for building of seismic velocity field and structure mapping by variation in velocity |
| Ma Haizhen1, Yong Xueshan1, Yang Wuyang2, Lu Lieqin2, Wang Xiaowei2 |
| Northwest Geologic Institute, CNPC Lanzhou City, Gansu |
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Abstract The paper analyzed the primary factors that have influence on mapping precision in traditional methods for building of seismic velocity field and structure mapping by variation in velocity and pointed out the reasons of big errors and poor accuracy in conventional methods.Starting from solving problems existing in traditional methods,the paper presented correspondently a new method for building of seismic velocity field and structure mapping by variation in velocity,pointed out the application conditions and demands of the method in a seismic working area with floating datum and expanded it in method of model-building in interval velocity suitable for depth migration.The techniques of horizon de一migration,lateral velocity spectrum section along horizon,3-D ray-tracing coherence inversion for traicing interval velocity,map migration for depth structure and building of velocity field and structure mapping in single horizon for separate reflected targets are adopted in the new method.All these measures can resolve the principal problems having influence on precision of velocity field and structure map in conventional method.The attached examples and practical applications in 10 working areas show that the method improved the precision of building of velocity field and structure mapping,which is a technique-advanced,time-efficient and practical method for velocity model-building and structure mapping.
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Received: 25 June 2001
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2002, Vol. 37 
