砂岩储层隔夹层的形成机理及分布特征——以萨中地区PⅠ2小层曲流河河道砂岩为例

GENETIC MECHANISM AND DISTRIBUTION FEATURES OF BARRIERS AND BAFFLES IN SANDSTONE RESERVOIR

剖析了萨中地区曲流河道砂内部的隔夹层的形成机理及分布特征,将曲流河道砂岩储层中夹层分为两种基本类型:①相邻洪水期间形成的泥质夹层,是相邻洪泛间悬移质沉积形成的,规模大、连续性好,但容易遭受剥蚀,有时保存不够完整;②每期大洪水中能量波动成因的夹层,是洪泛期水体能量波动形成的,规模小、连续性差,一般保存完整。研究区目的层的隔层分布频率比较低,但分布范围大,为天然堤、决口扇、河漫滩以及废弃河道成因。隔夹层的岩性以泥岩和粉砂质泥岩为主,物性差。侧积夹层的角度随点坝形成时期呈现不同的变化规律。

It is discussed the genetic mechanism and distribution features of the barriers and baffles in meandering river channel sandbodies, and divides the baffles in meandering river channel sandstone reservoirs into 2 basic types. The first type of baffle is muddy intercalation that is formed through suspension load deposition between two flood periods. They are characterized by large scale and good continuity, but are vulnerable to erosion and sometimes cannot be completely preserved. The second type is formed due to the fluctuation of water body energy during a flood period. They are characterized by small scale and poor continuity and are generally completely preserved. The barriers in the target in the study area are low in distribution frequency, but are large in distribution scale, and have originated from natural levee, crevasse splay, alluvial flat and abandoned channel. The lithology of the barriers and baffles are dominated by mudstone and silty mudstone with poor physical properties. The angles of lateral baffles show different change patterns for different formation times of point bars.