多滑脱层挤压构造结构特征与变形机制的定量研究-以塔里木盆地库车坳陷深层构造为例

A number of large and medium-sized oil and gas fields, such as Keshen 2 and 8 have been discovered, indicating the huge oil and gas potential and good exploration prospect in the deep strata of Kuqa depression. Study of the deep structure is critical to the further breakthrough of exploration and production of oil and gas in the western margin of the Tarim Basin. Meanwhile, Kuqa depression is a natural laboratory for the quantitative research on the characteristics and mechanism of structural deformation in the foreland fold-and-thrust belt. Study on Kuqa sub-salt deep structures will provide quantitative basis to help the theory improvement for the complex fold-and-thrust of the foreland basin. With deep structure as the key point, this proposal focuses on the detachment of fold belt. Based on the geological survey, seismic data interpretation, combined with physical and discrete element numerical modeling, we will carry out fine structural analysis and quantitative simulation of the sub-salt structures in the Kuqa depression, with the purpose to reveal the characteristics, the distribution, and the evolution of the sub-salt faults, confirm the composition, location, and distribution of the deep detachments, and explore the stress and strain distribution and its influence on reservoir properties in different structural locations of the deep strata in Kuqa depression.

克深2、克深8等一批大中型油气田的发现揭示了库车坳陷深层巨大的油气潜力及良好的油气勘探前景。深层构造研究是塔里木盆地西缘油气勘探生产进一步突破的当务之急。同时库车坳陷是开展前陆褶皱冲断带变形特征与变形机制定量研究的天然实验室。对库车盐下深层构造的研究有望为前陆盆地复杂褶皱冲断构造地质理论的完善提供定量依据。本申请以库车坳陷深层构造为重点，围绕褶皱带内滑脱层组合这一关键因素，拟通过地质调查和地震资料解释，结合构造物理模拟实验和离散元数值模拟，开展库车坳陷盐下构造精细解剖与定量模拟研究，揭示库车坳陷盐下断层的性质与时空演化规律，明确深部滑脱层的组成、位置、展布及其对库车坳陷盐下断层及褶皱形成演化的影响，探讨深层条件下不同构造部位应力应变分布特征及其对储层物性的影响。

本项目通过地表构造调查和地震资料精细解释，结合构造物理模拟实验和离散元数值模拟，定量研究库车盐下深层构造变形特征与变形机制，揭示库车坳陷盐下断层的性质与时空演化规律，确定深部有效滑脱组合特征、展布及其对库车坳陷盐下断层及褶皱形成演化影响，为前陆盆地复杂褶皱冲断构造地质理论的完善提供定量依据，探讨深层条件下构造应力应变对储层物性的影响，为塔里木盆地西缘深层油气勘探提供理论支持。综合野外地质考察、二维及三维工业地震资料解释与分析、钻井及重力异常等数据分析等方法，我们对库车坳陷构造差异演化特征、变形机制及控制因素做了系统的分析。研究结果表明库车坳陷具有明显的垂向分层、南北分带、东西分段的构造特征。坳陷内普遍发育双滑脱层褶皱冲断构造，上滑脱层（库姆格列木盐岩层）及下滑脱层（基底滑脱层）是控制本区垂向构造分层关键因素，古生代基底隆起控制了新生代盐层的分布，基底及盐层分布是影响库车坳陷沿走向构造差异演化及构造分段的主控因素；通过平衡剖面及沉积楔体面积深度分析，定量分析了库车坳陷盐下深层断层褶皱系统，明确了克拉苏断层以北主要发育基底卷入的高角度的逆冲构造，克拉苏断裂以南主要发育的滑脱构造，滑脱面深度约10km左右，结合楔状体临界角库伦楔模型分析，揭示了库车坳陷克拉苏构造带盐下楔状体的滑脱层为中下三叠统泥岩；通过构造解释与建模、构造物理及数值模拟研究了深层条件下构造应力应变对储层物性的影响，提出构造应力控制深层储层展布的观点，揭示了储层裂缝的主控因素，为库车前陆冲断带盐下超深层油气勘探与开发提高了理论支持。