多期裂陷盆地斜向伸展变形主控因素分析——来自砂箱物理模拟实验的启示

Main controlling factors on oblique extensional deformations in multiphase rift basins: insights from analogue experiments

王琦 孙永河 巩磊 王有功 常德双 张万福

WANG Qi SUN Yonghe GONG Lei WANG Yougong CHANG Deshuang ZHANG Wanfu

1. 东北石油大学 秦皇岛校区, 河北 秦皇岛 066004; 2. 重庆科技大学 石油与天然气工程学院, 重庆 401331; 3. 东北石油大学 环渤海能源研究院, 河北 秦皇岛 066004; 4. 东北石油大学 三亚海洋油气研究院, 海南 三亚 572025; 5. 中国石油 东方地球物理公司研究院, 河北 涿州 072751

1. Northeast Petroleum University-Qinhuangdao, Qinhuangdao, Hebei 066004, China; 2. School of Petroleum Engineering, Chongqing University of Science and Technology, Chongqing 401331, China; 3. Bohai Rim Energy Research Institute, Northeast Petroleum University, Qinhuangdao, Hebei 066004 China; 4. Sanya Offshore Oil & Gas Research Institute, Northeast Petroleum University, Sanya, Hainan 572025, China; 5. Research Institute of Bureau of Geophysical Prospecting INC., PetroChina, Zhuozhou, Hebei 072751, China

为了探讨多期裂陷盆地中先存断裂及其与不同伸展方向之间夹角(斜度α)对斜向伸展变形和洼槽结构的影响，利用砂箱物理模拟实验，基于相似性原理，设计了三组物理模拟实验，即不同斜度(α)斜向伸展物理模拟实验和两组斜向伸展—走滑叠加变形物理模拟实验。实验结果表明：(1)多期裂陷盆地中，伸展方向与先存断裂之间的夹角变化控制着走向滑动分量和倾向滑动分量的比例，影响洼槽结构，夹角越大，倾向滑动分量越大，洼槽宽度越大；反之，洼槽宽度减小。(2)受先存断裂分布的影响，不同演化阶段，先存断裂再活动方式不同，对于斜向伸展—走滑叠加变形过程，先存走滑断裂与边界断裂之间的距离较大时，洼槽呈单断半地堑特征；二者间距较小时，走滑断裂也控陷，洼槽呈现双断地堑结构。(3)多方位展布的先存边界断裂再活动控制形成的洼槽深度和压扭褶皱幅度也受二者距离的影响，随着先存边界断裂与走滑断裂距离的增加，张扭区洼槽深度逐渐增大，压扭区褶皱幅度逐渐增加；反之，洼槽深度越小，褶皱幅度越低。

In order to investigate the influence of pre-existing faults and their angle (α) with different extension directions on oblique extension deformation and sag structure in multiphase rift basins, three sets of analogue experiments were designed based on the similarity theory, including oblique extensional physical simulation experiments with different angles (α), and two sets of physical simulation experiments of oblique extensional and strike-slip deformations. The experiment results showed that: (1) In multiphase rift basins, the angles between the extension direction and pre-existing faults controlled the ratio between the strike-slip component and the dip-slip components, affecting the sag structure. As the angle increased, the dip-slip component and the width of the sag increased. Conversely, when the angle decreased, the sag width decreased. (2) Affected by the distribution of pre-existing faults, the reactivation style of pre-existing faults differed at different evolutionary stages. During the oblique extensional and strike-slip deformation, when the distance between the pre-existing strike-slip fault and the boundary fault was large, the sag showed a single-fault half-graben characteristic. When the distance between them was small, the strike-slip fault also controlled subsidence,and the sag presented a double-fault graben structure. (3) Sag depth and the amplitude of the compression and shear folds controlled by the reactivation of pre-existing boundary faults with multi-directional extension were also influenced by the distance between the faults. As the distance between the pre-existing boundary faults and strike-slip faults increased, the depth of the sag in the extensional-shear zone gradually increased, and the amplitude of the folds in the compressional-shear zone gradually increased. Conversely, the sag depth and fold amplitude decreased.

河北省自然科学基金项目(D2024107006)和国家自然科学基金项目(42172162和42072155)联合资助。

https://doi.org/10.11781/sysydz2025020441