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针对陆相断陷盆地砂体分布规律的复杂性,提出一种立足于整个“物源-搬运-沉积”过程的基准面调控下物源体系、沟谷体系、坡折体系3大古地貌要素耦合的砂体预测方法。该控砂机制以基准面为杠杆,以靠近湖盆边缘的平衡位置为支撑点,以古地貌要素为研究对象,强调动态因素调控静态因素,并充分考虑流态转换和砂体成因。古地貌要素耦合方式理论上有8种,分别对应最差至最优的不同耦合沉积效应;在基准面升降过程中“跷跷板”效应的影响下,陆相断陷盆地中古地貌要素的耦合方式发生改变,导致砂体的成因、迁移方式和沉积环境等显著变化,进而控制砂体的分布规律。在该控砂机制指导下,分析了苏北盆地高邮凹陷和北部湾盆地涠西南凹陷的砂体发育规律,对控砂机制的有效性和实用性进了实践检验。
Aiming at the complexity of distribution of sand bodies in terrestrial faulted basins, a three-paleogeomorphological element coupling system of source rocks, valleys and slope-break systems under the control of datum plane of the whole “source-transport-sediment” Sand body prediction method. The sand control mechanism takes the datum as a lever, takes the balance position close to the edge of the lake basin as the support point, takes the paleogeomorphology elements as the research object, emphasizes the dynamic factors regulating the static factors, and fully considers the fluid regime transformation and the sand body genesis. In theory, there are eight kinds of coupling elements, which correspond to the worst to optimal coupling and sedimentation effects respectively. Under the influence of the “seesaw” effect during the rise and fall of the reference plane, the coupled pattern of the middle- Change, resulting in significant changes in the formation of sand bodies, migration patterns and sedimentary environment, and then control the distribution of sand bodies. Under the guidance of the sand control mechanism, the sandbody development of the Gaoyou sag in the Northern Jiangsu Basin and the southwestern depression in the Baobei Bay Basin was analyzed, and the effectiveness and practicability of the sand control mechanism were tested.