Experimental Research Of Deep Seismic Reflection Data Acquisition And Processing Technology In Qiangtang Terrane

Deep seismic reflection profiling technique is one of the geophysical methods based on the principle of seismic waves; it is used to detect the deep structure of the Earth. Since the 1960s, the way of data acquisition technology and processing methods in deep seismic reflection have made considerable progress. In the Qiangtang China use deep seismic reflection to study deep structure, especially the crust structure of the Qiangtang terrain in Tibet Plateau. There are a lot of new problems which appeared. On the basis of deep seismic reflection data acquisition parameters demonstration, with theoretical formulas in this thesis, a long deep seismic reflection profile across the whole Qingtang terrain is acquired based on the new deep seismic reflection data collected between 2007-2010 by CAGS and the oil seismic data collected between 1996-1997 by CNPC, which reveals the fine structure of deep cust under Qiangtang terrene.This thesis mainly includes the following aspects:1,Using the theoretical formulas to demonstrate the deep seismic reflection data acquisition parameters. The author consider it reasonable to use deep-well combination within huge dose explosive stimulate, long permutation and combination receiving, high stacking acquisition technology in the Qiangtang terrain of Tibet plateau. Acquisition practices has proved that, with the advanced equipment, reasonable observation system, acquisition parameters and strict quality conditions, deep seismic reflection data can be obtained even in a complex area.2,In this thesis, there are several new technologies applied through the deep seismic data processing. such as:fine prestack data combination processing technology, static correction with topographic inversion without ray, wavelet transform to improve signal-to-noise ratio, high precision velocity analysis, irregular surface prestack migration technology, etc, these combination methods used in deep seismic reflection processing has achieved significant results.3,There exists at least three difficult points in the progress of deep seismic reflection data processing in qiangtang terrene of Tibet plateau. First is how to improve the SNR of data while information of low frequency must be protected, which means repressing interference wave of low frequency effectively and reserving useful deep information. The second is about static correction. To solve this problem, the ray tomography static correction technology is applied which has an advantage of avoiding ray shadow problems caused by great lateral changes of near-surface velocity so that it results in more accurate static correction calculations.The third one is stack velocity analysis with long distance offset. The high-order NMO correction technology is used to solve the problem when the big offset can't do normal moveout.