海上煤田高精度三维地震采集技术及应用效果

3-D high-precision seismic acquisition techniques in ocean coalfield and application effects.

北皂煤矿北部海域 (属渤海 )的三维勘探是我国首次针对海上煤田开展的高精度三维地震勘探。勘探面积为6 .4 4 km2 ,工区水深为 0～ 12 m,目的层埋深为 80 9m。工区地质构造走向不一致 ,断层比较发育。勘探目的要求查清煤层中落差为 3～ 5 m的断层与褶曲。为此 ,在勘探对策上 ,着重采取了 3项措施 :1优化观测系统设计 ;2合理选择气枪沉放深度与组合方式 ;8保证检波器准确定位。通过上述措施所获得的高精度地震剖面 ,主要目的层波组特征清楚 ,连续性好 ,信噪比高 ,深度误差不大干 4 m ,基本能查清煤层中落差为 5 m以上的断层和褶曲。

The 3-D seismic exploration in north sea area of Beizao coalfield ( belongs to Bohai sea ) is the first 3-D high-precision seismic exploration aimed at offshore coalfield in China. The exploration area is 6.44 km 2,the water depths of work area are be-tween 0～12m,the depth of target is 809m. The ge-ologic structural trends in work area are not con-sistence. There are developed faults. The goal of the exploration is to clarify the relief of faults and folds in relief of 3～5m in coalfield. Therefore, we put emphasis to use 3 measures : ①optimizing the design of geometry; ②reasonably choosing the depth of air-guns and their array pattern;③guar-anteeing the correctly positioning of geophones.The gained high-precision seismic sections after us-ing abovementioned measures are characteristics of evident events feature,good continuity and high S/N ratio in major targets. The errors of depth are no greater than 4m,that can basically clarify the relief of faults and folds above 5m.