克拉苏构造带博孜段古隆起及盐层对盐下冲断带的控制

The control of paleo-uplift and salt layer on subsalt thrust belt in Bozi Section of Kelasu Tectonic Belt

克拉苏构造带是库车坳陷油气勘探的主要区带。以克拉苏构造带博孜段三维地震资料为基础,进行一体化建模,明确盐下冲断带构造变形差异及古隆起、盐层分布特征;基于物理模拟实验,分析古隆起、盐层对盐下冲断带的控制作用。结果表明:研究区薄盐层分层作用差,断裂数少,规模大,易传递至盐上层;厚盐层易形成盐背斜和盐焊接等构造,盐下层多排逆冲断裂向盆地内部传递;古隆起发育区北翼断裂表现为倾角小、水平断距大和沿斜坡滑脱等特征,古隆起不发育区断裂表现为倾角陡、断距大且断裂数多的特征。古隆起发育区易形成滑脱冲断和盐背斜构造,古隆起不发育区易形成阶梯冲断和盐焊接构造;古隆起与盐层的双重叠加是影响盐下冲断带复杂变形的主要因素,古隆起限制冲断体系变形空间,盐层缓冲应力传递,起调节作用。该结果对研究区下一步天然气勘探开发具有指导意义。

The Kelasu Tectonic Belt is the main zone for oil and gas exploration in Kuqa Depression.Based on the three-dimensional seismic data of the Bozi Section of the Kelasu Tectonic Belt,the integrated modeling is carried out to clarify the structural deformation difference of the subsalt thrust belt and the distribution characteristics of paleo-uplifts and salt layers.Based on the physical simulation experiment,the control effect of paleo-uplift and salt layer on the subsalt thrust belt is analyzed.The results show that the thin salt layer in the study area has poor stratification,few faults,large scale,and is easy to transfer to the upper salt layer;the thick salt layer is easy to form salt anticlines and salt welding structures,and the multi-row thrust faults in the subsalt layer are transferred to the basin.The faults in the north wing of the paleo-uplift development area are characterized by small dip angle,large horizontal fault distance and slippage along the slope.The faults in the undeveloped area of the paleo-uplift are characterized by steep dip angle,large fault distance and many faults.The development area of the paleo-uplift is easy to form detachment thrust and salt anticline structure,and the undeveloped area of the paleo-uplift is easy to form stepped thrust and salt welding structure.The double superposition of the paleo-uplift and the salt layer is the main factor affecting the complex deformation of the thrust belt.The paleo-uplift limits the deformation space of the thrust system,and the salt layer buffers the stress transfer and plays a regulatory role.The results have guiding significance for the next natural gas exploration and development in the study area.