层析静校正技术在山地复杂地区三维地震勘探中的应用

勘探区位于鄂尔多斯聚煤盆地东缘,河东煤田南部,工区内地形起伏较大,黄土冲沟发育,多成“U”字形深切冲沟,部分沟壁可达85°,高差20～60m。地形西低东高,最大高差205m,第四系覆盖层厚度0～120m,低速带速度横向变化较大,存在严重的长、短波长剩余静校正问题。如在该区钻孔CB77至CB73,其2~#煤层底板为同样标高,但在折射静校正后的速度分布图上,钻孔CB73处却存在一明显异常区,通过使用层析静校正方法,很好地解决了这一问题。另外,在该区陷落柱判识方面,利用层析静校正方法取得的时间剖面,其陷落柱边界、高度、形态,比采用常规静校正更清晰。

Application of Tomographic Statics in Complicated Mountainous Area 3D Seismic Prospecting

The prospecting area is located on the eastern margin of Ordos coal basin,southern part of Hedong coalfield,the area has undulating relief,U shaped incised loess gullies are well developed,and part of gully wall angle can be as high as 85o,elevation difference 20-60m.The relief is high in east,low in west,maximum drop in level 205m.The Quaternary overburden thickness is 0- 120m,lateral varying of weathering velocity is relatively large,serious long and short wavelength residual statics problems are existed. Such as in boreholes CB77 to CB73,their No.2 coal seams have same elevation,but on the velocity distribution map after refraction statics,an obvious anomaly is existed around the CB73 borehole,the problem has solved after tomographie statics.Besides,in subsided column identification,the boundary,height and shape of columns are clearer on time sections through tomographic statics then normal statics.