The travel times of coherent events in seismic surveys of the crust principally give information about the low spatial frequency velocity field; details of the seismic signatures of backscattered events principally give information about the high spatial frequency of the velocity and density fields (which can be represented by pseudo well logs). Travel time inversion is beginning to find practical application in the oil industry. However, commercially useful extraction of pseudo well logs from most seismic data sets is some time off. The key to both solutions lies in a successful coherent event picking procedure that can operate accurately and stably in the presence of both random and coherent noise. The accuracy of the travel time inversion will increase with the number and accuracy of the picks. Picks must be made based on target wavelet estimates at various source-receiver offsets. These target wavelets can be inverted for the pseudo well logs. Phase I will develop a seismic modeling-aided, coherent event decomposition class of picking algorithms that should be accurate and stable in the presence of both random noise as well as interference from other coherent events. Simultaneously, it should be able to extract accurate target wavelet estimates at each offset that have a maximized signal-to-noise ratio.Anticipated Results/Potential Commercial Applications as described by the awardee:This project will provide the capability to extract virtually all the information concerning the subsurface that resides in a given set of surface and borehole seismic data, even in complex geologic environments. The output will be in the form of pseudo well logs of p-wave velocity, s-wave velocity, percent anisotropy, and perhaps Q (dissipation factor) in each nominal common depth point bin. Such results would drastically reduce the percentage of dry holes in both exploration and production drilling.
