东濮凹陷混积岩传输路径与沉积模式研究

The mixed carbonate-siliciclastic deposits are widely developed in Bohaiwan Basin，Qaidam Basin and other petroliferous basins in China.As the demand for oil and gas grows constantly,the tight carbonate cemented sandstone reservoir and dolomite reservoir become the new exploration targets in sedimentary basin.For the complex fault-bounded depression，it is difficult to fully understand the whole configuration distribution of the depositional system just by means of the regional geology study and mono-factor analysis method.The traditional method usually leads to the nonuniqueness of the deposit pattern recovery in the tectonic transfer zones.The combination of sediment routing system analysis and flume experiment could reduce the nonuniqueness and improve our understanding to deposit mechanism of sediment basin.In this study,the third member of Shahejie Formation,which was formed during rifted stage, is taken as the main target for the study of mixed deposit.Based on the seismic data，well-log data and laboratory results of drill cores in the study area,we would firstly conduct structural and balanced section analysis to the Baimiao-Qiaokou transfer zone,and make sediment paleogeomorphic restoration for diffient sections in the transfer zone.Based on the previously restored models,we plan to carry out a systematical flume experiments to investigate the influences of sediment source,flow pattern and topography on the production of mixed deposits.we will try to generalize the implicatons on the cause of carbonate cement,anhydrite cement,mud and dolomite,derived from the above scaled analogue models,and provide new insights for the exploration of the unconventional reservior.

陆源碎屑-碳酸盐岩混合沉积成因的湖相致密钙质砂岩和泥质白云岩储层，成为新的增储领域。然而湖相混积岩的物质来源具有多解性，其传输路径和沉积场所与构造变换带的关系尚不明确。针对湖盆变换带的沉积动力学特征，项目以东濮凹陷白庙-桥口-文东变换带的沙三段为靶区，采用典型区域解剖与水槽模拟相验证的方法，根据地震、钻井、岩心等资料，开展沉积路线系统研究，分析混积岩中易溶组分与物源成分、剥蚀序列的关系。开展变换带的构造解析、平衡剖面分析，经古水深校正，建立古地貌演化模型。基于该模型开展水槽模拟实验，单因素分析物源成分、水流方式、古地貌演化和湖平面变化对混合沉积的影响。校验湖盆河流入口和沉积物传输路径的选择性，总结早期碳酸盐胶结物、泥灰岩及白云岩的分布规律。构建湖相混合沉积的动态模式、比拟实验沉积模式，预测混积岩的三维空间展布，指导非常规储层勘探，对恢复古构造、古地理及古气候，丰富湖泊沉积学理论有重要意义。

湖相混积岩的物质来源具有多解性，其传输路径、沉积场所与构造变换带的关系尚不明确。项目以东濮凹陷白庙-桥口-文东变换带的沙三段为靶区，采用典型区域解剖、现代沉积调查与水槽模拟相验证的方法，根据地震、钻井、岩心等资料，开展沉积路线系统研究，分析混积岩中易溶组分与物源成分、剥蚀序列的关系，开展变换带的构造解析、平衡剖面分析，经古水深校正，建立古地貌演化模型。基于该模型开展水槽模拟实验，单因素分析物源成分、水流方式、古地貌演化和湖平面变化对混合沉积的影响。校验湖盆河流入口和沉积物传输路径的选择性，总结了早期碳酸盐胶结物、泥灰岩及白云岩的分布规律。项目取得以下主要成果：（1）华北地台古生代的碳酸盐岩和中生代的碎屑岩为东濮凹陷混积岩的主要物质来源，此类母岩的抗风化能力小，因而盆地内的充填物质以细粒沉积为主，具有富含碳酸盐岩碎屑和石膏的特征。（2）东濮凹陷沙河街组的干层主要为致密钙质砂岩，其分布明显受控于沉积相带，主要形成于湖平面下降期的三角洲前缘远端或主水道侧翼，为化学风化产生的钙质胶结物大量充填粒间空隙导致。（3）厘定了东濮凹陷陡坡带的沉积几何学特征，沉积中心与洼陷中心不一致，其中沉积中心靠近盆缘断层，而洼陷中心靠近盆地内部，富有机质暗色泥岩与湖相深水成盐共存于洼陷中心，前者形成于广水期,后者发育于湖盆的低位期。（4）根据现代沉积调查和水槽模拟实验的类比分析，认为混合沉积过程中的岩盐沉积中心与洼陷中心具有一致性，而且岩盐的结构跟沉积环境密切相关，盆缘滨岸带的岩盐多为薄层状与砂岩共存，晶体粒度小；而洼陷带以粗粒结晶的盐岩为主，单层厚度大，常与暗色泥岩互层。湖相混合沉积模式的构建,可以预测混积岩的三维空间展布，指导非常规储层勘探，对恢复古构造、古地理及古气候，丰富湖泊沉积学理论有重要意义。