三维空间速度分析技术在三道桥东地区的应用

Application of 3D spatial velocity analysis technology in the east of Sandaoqiao area

受构造运动影响,新疆维吾尔自治区阿克苏地区库车县三道桥东地区地层特别是前中生界和中生界下部地层在三维空间上分布变化较大,局部缺失严重,地质条件较复杂,造成地震平均速度横向上发生较大变化,增大了速度分析的难度,常规分析思路难以准确落实无井区速度变化,导致无法准确识别该区地质构造特征。针对三道桥东地区的地震地质情况,开展了以地震速度资料为主体的井震联合速度分析,利用地震速度场平均速度等速面为趋势控制条件,通过空间模拟延拓,建立三维空间速度场,进行变速度目的层深度构造成图。通过精细速度分析与变速时深转换,提高了井震吻合率,真实刻画了地下构造形态。分析认为,地震速度谱是地震勘探构造研究的关键资料,对于构造刻画起到了关键控制作用。

Affected by the tectonic movement,the strata in the east of Sandaoqiao area,Kuqa County,Aksu prefecture,Xinjiang Uygur Autonomous Region,especially the pre Mesozoic and lower Mesozoic strata,have great changes in 3D spatial distribution,with serious local missing and complex geological conditions,resulting in great changes in the average seismic velocity horizontally,increasing the difficulty of velocity analysis.It is difficult to accurately determine the velocity change in the area without well location in conventional analysis,resulting in the inability to accurately identify the geologic structure features of the area.Therefore,in view of the actual seismic geological conditions in the east of Sandaoqiao area,the velocity analysis of well-seismic joint was carried out,which is mainly based on the seismic velocity data.Using the average velocity isovelocity surface of the seismic velocity field as the trend control condition,the spatial simulation continuation is carried out,the 3D spatial velocity field is established,the depth of the target bed with variable velocity is constructed into a map.Through fine velocity analysis and vaviable velocity time-depth conversion,the well-seismic coincidence rate is improved,and the attitude of underground structure is characterized truly.The analysis shows that the seismic velocity spectrum is the key data for the study of seismic exploration structure and plays a key role in controlling the structural characterization.