Research And Application Of High-precision Velocity Model Building Technology For PSDM

With the development of our economy,increasing demand for oil and gas resources call for higher standard of seismic exploration.The target of exploration gradually shifts from simple structural reservoirs to complex lithologic reservoirs,subtle reservoirs,combination reservoirs or unconventional reservoirs with features of smaller geological scale,increased complexity,high heterogeneity and serious lateral variation for velocity.Currently,pre-stack depth migration is a key technology to solve seismic imaging problems of complex structure,which is more sensitive to velocity than pre-stack time migration.So,if we want get the best imaging migration result,the key is the velocity model whether or not accurate.The velocity model building should be data driven and based upon offset consistency;that is,the data with multiple have negative effects on inversion,and The velocity mode whether or not accurate direct influence pre-stack depth migration imaging quality,they are complemented each other.But it is difficult to get the high-precision velocity mdeling in complex areas,those are where the pre-stack depth migration is better than pre-stack time migration.High-precision depth migration velocity modeling technology refers to adding various technical means to the process of depth migration modeling in order to improve the accuracy of velocity model.How to build high precision velocity model in high-steep structure area high-steep structure such as area,the best way is taking advantage of the strong coupled relationship between velocity and depth for better inversion and ultimately provide a high-precision velocity field for pre-stack depth migration.At the same time,in order to improve the precision of inversion.How to use well and fault informations to constraint velocity modeling precision is the most diffcult problem for the pre-stack depth migration.Based on the area actual seismic data,this paper illustrates the high-precision velocity modeling technology.The calculation method and methods of inversion are studied.In order to improve the precision of inversion.Before the inversion,we do same deniose and demultiple work in the observed data.Based on tomography inversion velocity theory use well data and fault data to constraint condition,increase the precision of convented tomography inversion.Practical experiment results indicate,use well control and fault control combine tomography inversion to build velocity modeling,it is a better way to improve the final pre-stack depth migration result.We have test and research on a practical 3D seismic data in the areas,has formed a series of building high-precision velocity modeling methods in complicated high-steep structure areas,providing a reliable and perfect method for the exploration and processing work.