准噶尔盆地南缘山前带构造变速成图

Application of varying velocity mapping technique for mountain front in southern Junggar basin

(1.中国石油化工股份有限公司石油勘探开发研究院西部分院,新疆乌鲁木齐,830011;2.中国石油化工股份有限公司石油勘探开发研究院南京石油物探研究所，江苏南京210014；3.中国石油大学,北京102249)

Western Branch of Exploration and Development Research Institute, SINOPEC, Urumqi 830011, China

准噶尔盆地南缘山前带构造复杂，深部地层横向速度变化剧烈。为了提高构造成图的精度，采用变速成图技术对研究区进行了构造成图。首先将叠后时间偏移域(简称偏移域)的T0层位数据反偏移(偏移的逆运算)到水平叠加时间域(叠加域)；然后利用叠加速度反演方法求取叠加域T0层位数据网格点所对应的层速度值；最后采用三维射线追踪图形偏移方法将T0图转换成深度图。对研究区变速成图结果与简单的时-深关系转换结果进行了对比，可以看出变速成图方法有效提高了构造图的精度，在工区的正南边发现一个新的背斜圈闭。

The structures of mountain front in southern Junggar basin are complex and the variation of lateral velocity in deep formation is considerable. In order to improve the accuracy of structure mapping, varying velocity mapping technique was used to map the structures. Firstly, the T0 layer data of post-stack time migration domain (abbreviated in migration domain) was de-migrated into common-depth-point-stacking time domain (abbreviated in stacking domain). Then, stacking velocity inversion method was used to obtain the horizontal velocity responding to the grid points of T0 layer data in stacking domain; finally, 3-D ray map-tracing migration method was applied to convert T0 map into depth map. The varying velocity mapping result was compared to simple time-depth relationship transformation result, showing that the varying velocity mapping technique can effectively improve the accuracy of structure maps and an anticlinal trap was discovered in the south of the working area.