Three-component seismic profiling at the Chinese Continental Scientific Drilling site
中国大陆科学钻探孔区的数字三分量反射地震调查

This paper introduces the data-acquisition and processing method applied in the 3-component seismic investigation in Chinese Continental Scientific Drilling site as well as some primary results of the survey. In order to obtain good converted wave signals, primary wave-field investigation is required for designing the seismic configuration parameters. There are three difficulties should be overcome in the 3-component data processing, they include statics, S-wave velocity analysis and converted-wave stacking. The reason why the 3- component survey is usually performed after completion of the drilling and VSP investigation is because the dataprocessing and interpretation need drilling and VSP data. For instance, without core velocity measurements or VSP interval velocity data, one can hardly establish a reliable S-wave velocity model, and complete the X- and Y- component data processing and interpretation. Comparing with common Z-component surveys, horizontal components show the converted reflectors that can provide particular and significant information related to fluids or anisotropy of deep rocks. On the left part of the X-component depth-stack profile, a special layer of dense horizontal reflectors appears at depth 2600 - 3400 m, which is different from P-wave reflection profile and correlated to gas anomalies of CH4 and CO2, implying a newly-developed fluid and fracture zone.