陆相断陷盆地源-汇时空耦合控砂原理:基本思想、概念体系及控砂模式

Controlling sand principle of source-sink coupling in time and space in continental rift basins: basic idea, conceptual systems and controlling sand models

以渤海海域为例,首次尝试将从"源"到"汇"的研究思路应用到断陷湖盆沉积体系研究中来,提出将沉积物从剥蚀到搬运、堆积的整个沉积动力学过程看成一个完整的源-汇系统来探讨砂岩的富集机理。在复杂的陆相断陷盆地,一个砂岩富集区常常都对应一个完整的源-汇时空耦合系统。源-汇时空耦合体系包括有效物源体系、高效汇聚体系和基准面转换体系,其中有效物源体系包括显性物源体系和隐蔽性物源体系,隐蔽性物源体系包含时间上的隐蔽性物源体系和空间上的隐蔽性物源体系,识别隐蔽性物源体系对陆相断陷盆地储层预测具有重要的意义;高效汇聚体系由输砂通道、坡折带、碎屑物质的可容纳空间共同构成;基准面转换体系主要控制了一个层序内砂体发育的时期。渤海海域复杂的构造演化形成了盆缘断裂墙角式源-汇体系、盆缘断裂走向斜坡式源-汇体系、盆缘断裂相向消减式源-汇体系、盆缘断裂沟谷式源-汇体系、盆缘走滑断裂源-汇体系、凸起轴向源-汇体系及缓坡沟谷式源-汇体系等7种常见的源-汇时空耦合控砂模式;勘探实践证明,在源-汇时空耦合控砂体系这一认识指导下,大大提高了渤海古近系储层预测成功率,为推动渤海古近系勘探做出了重要贡献,这对其他类似盆地沉积体系分析和储层预测具有重要的借鉴意义。

As a study case in Bohai water, an idea from ＂source＂ to ＂sink＂ was firstly attempted to be applied to the sedimentary system in rifted lake ba sins, and it was considered that the entire dynamic process from sediment erosion, transportation to accumulation should be seen as a complete source - sink system to discuss the sand enrichment mecha- nism. A sand enrichment area often corresponds to a complete time-space coupling system of source- sink in any complex continental rift basin, and atime-space coupling system of source-sink general- ly includes three sub-systems, namely effective provenance sub-system, effective accumulation sub-system and base-level conversion sub-system. The effective provenance sub-system can be divided into the explicit and implicit types, and the implicit type can be again divided into the time-implicit provenance system and space-implicit provenance system. It is of great significance in reservoir pre- diction to identify the implicit provenance systems in a continental rift basin. The effective accumulation sub-system is composed of some sediment transport channels, slope break zones and detritus accommodation space. The base-level conversion sub-system will mainly control the period of sandbody development in a sequence. The complex tec- tonic evolution in Bohai water has resulted 7 controlling sand models of source-sink coupling in time and space, including the corner-style sourcesink system along basin margin faults, the strike-slope-style source-sink system along basin margin faults, the opposite-consumption-style source-sink system along basin margin faults, the valley-style source-sink system along basin margin faults, the strike-slip fault source-sink system along basin margin, the valley-style source-sink system along uplift axes and the valley-style source-sink system on ramps. The exploration results have indicated that the controlling sand idea of source-sink coupling in time and space can significantly improve the success rate of Paleogene reservoir prediction in Bohai water, making great contributions to promoting the Paleogene exploration. This idea will also be an important reference for sedimentary system analysis and reservoir prediction in other similar basins.