基于三维地震资料的构造转换研究——以库车坳陷前陆冲断带KL1号、KL2号构造为例

Research on Structural Transfer Based on 3D Seismic Data——A Case Study from KL1 and KL2 Structures of Foreland Thrust Belt, Kuqa Depression

转换构造普遍发育于各类型的沉积盆地内,其本质为在区域应力场作用下盆地内发生的差异变形现象,大多表现为多条断层或褶皱沿走向的相互转换。由于转换构造往往表现为复杂的构造形态,刻画难度大。三维地震资料不但提高了地震成像质量,同时也反映了地下构造"体"的信息,为研究转换构造提供了有力的依据。利用最新采集的三维地震资料,对库车前陆冲断带内的KL1号、KL2号构造的三维空间形态、相互转换关系进行研究,研究结果表明:①KL1号、KL2号构造为发育在库车前陆冲断带的大型冲起构造,该类构造主要由两条反向倾斜断层及其间夹持的背斜组成。②在挤压作用与走滑作用的影响下,KL1号构造与KL2号构造间存在着明显的构造转换作用,表现为背斜的翼部与核部间的差异对接特征,在剖面上表现为复杂的构造样式。③构造活动定量分析表明,KL1号构造与KL2号构造具有侧向生长特征,其演化经历了初始低幅度褶皱、反向断层冲起构造、侧向生长、走滑转换4个阶段。④受控断裂的活动的差异性影响,KL1号构造与KL2号构造保存条件差异较大,KL2号构造天然气富集而KL1号构造含油气性较差。

Transfer structure developed in different types of basin. The inherence of the structure is various deformation of basins under regional stress field. It was always formed with several faults or folds in strike directions and displayed the transformation between each other. Because of the complex feature of the structure, it is difficult to be described. Using 3D seismic data could not only enhance the quality of the profiles, but also provide the 3D information about the geology body which makes the research on transfer structure better. Based on up-to-date 3D seismic data, research is conducted on the 3D geometry and interconversion about KL1 and KL2 structure in Kuqa foreland thrust system. Results show that： （1） KL1 and KL2 are pop-up structures formed by two opposite inclination thrust faults and an anticline between them. （2） There are complex structures in this belt which perform as differential joint of the core and the limb of the anticline under the effection of transpression. （3） Quantitative analysis of fault activity shows that KL1 and KL2 have experienced initiative low anticline stage, pop-up structure stage, lateral growth stage and strike-slip transfer stage. （4） The preservation condition which is influenced by fault activities is different in KL1 and KL2. KL2 structure is rich in gas. The petroliferous property of KL1 structure is poor.