A Study On Geometry Of Off-line Seismic Data Acquisiton In Eastern Gansu Province

Eastern Gansu Province in Erdos Basin has complex surface conditions and the low velocity zone is heterogeneous seriously. The seismic data signal-to-noise ratio and resolution were lower, make it hard to meet the need of the development of oil and gas. Therefore, it is very important to search for the method of data acquisition for high signal to noise ratio and high resolution seismic data. In order to improve signal-to-noise ratio and resolution of loess seismic data, the off-line seismic data acquisition method was invented.The main parameters of geometry of off-line seismic data acquisiton contain these parameters, ?X, Xmax, Xmin, Y(off-line distance),RLI, Swatch,Fold and so on. The Y is the most important parameter to research. Y is under the control of the errors of off-line seismic data acquisiton and of the ablility to suppress noise. The best of Y is 1200 m. These parameters are considered appropriate, including ?X =25m, Xmax=5837.5m, Xmin=62.5,Y= 1200 m, RLI=50m, Swatch=4, Fold=155 and 310 for off-line acquisiton. In the Loess Hilly Region, the shot hole depth is determined according to the lithology and water saturation. Shot-array is necessary means to improve shot energy. The depth of hole depends on the thickness of the low velocity zone. Total amount of dynamite is 20 kg as least. The total dose of about 30 kg to ensure sufficient energy. Receiver- array is necessary to improve the signal to noise ratio. The 1-meter-long group interval can suppress noise well. In order to ensure the group interval is longer enough and to improve the signal-to-noise ratio, can be appropriate to relax the Receiver- array of height limitation. Tomography without ray tracing static correction can be better to solve the problem of static correction in Loess Plateau. Adaptive filtering and F-K combined denoising is a suitable method for off-line data processing.