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地球学报 1996
Data Acquisition of the First Super-Deep Seismic Profile in Qinghai Tibetan (Xizang) Plateau and the Method of its Processing
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Abstract:
The pilot survey of the Sino-American project INDEPTH has provided a highresolution, high-signal-to-noise ratio, near-vertical incidence reflection profile with abundant reflection information, which along with others yields clearly the Main Himalayan Thrust (MHT) and Moho discontinuity at a depth of 70-80km. There still are observed reflections beneath the Moho discontinuity. It is demonstrated by facts, that the near-vertical reflection technique can receive reflections from a depth of 70-80km, with three technical measures, such as 50m deep shot holes, 50kg dynamite and 50s superlong recording time, taken. It is obvious, that both the depth o f shot hole and the lithology excited are interdependent factors, affecting recording quality. Data analysis indicates, that shot in a single drill hole of depth more than 25m yields good recording,while array shot in drill holes of depth less than 25m can hardly receive deep reflections. The recording quality could be much improved with technical approaches, as slurry cementing and tamping after charging. During seismic data processing in view of the fact, that the lithology excited along the profile is varied very dramatically. surface consistency processing of wavelets and noise elimination were made, resulting in great improvement of the deep reflection stacked section in quality.