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对以往研究较少 ,并在油田勘探阶段及开发初、中期地质研究中被遗漏或忽视的决口水道的成因、沉积特征与模式、空间分布及在油田开发中的意义进行了研究与探讨。指出决口水道是在河流及三角洲沉积体系中 ,由主河道于大洪水期冲裂决口后 ,在广阔河道间形成的具有固定路径及一定限流作用的极窄、浅的短程小型水道。相当于新河道形成早期的“小型冲沟”阶段 ,其形成后对原主河流流量影响较小。其与河流沉积相比 ,具有粒度细、分选稍差、含泥量稍高、层理规模小、冲刷弱、略显正旋回、储层物性略差 ,特别是砂体极薄 ( <2 5m)而窄 ( <10 0m)等特点。建立了渐弱消失型、分枝型、末端扇型和汇入型 4种沉积模式。因其窄小分散而形成小而肥的井网控制不住型或注采不完善型剩余油富集砂体 ,又因其数目众多 ,而具有可观的剩余油储量 ,所以 ,其在油田挖潜及油田地质研究中具有重要意义。
The causes, sedimentary characteristics and patterns, spatial distribution and the significance in the development of oilfields were studied and researched in the past with few studies on the formation of bursts of waterway which were omitted or neglected in the oilfield exploration stage, initial and medium-term geological research. It is pointed out that the Bukou Estuary is a very narrow and shallow short-range small waterway with a fixed path and a certain current-limiting effect formed in the vast river between the main river and the delta sedimentary system. Which is equivalent to the “small gully” stage of the early formation of the new channel, which formed little impact on the flow of the original river. Compared with the river sediments, it has the characteristics of fine grain size, slightly poor sorting, slightly higher mud content, small bedding scale, weak erosion and slightly positive cycle, and slightly poor reservoir physical properties 5m) and narrow (<10m) and other characteristics. Four types of sedimentary models of fading vanishing type, branch type, end fan type and import type were established. Because of its narrow dispersion and the formation of small and fat well pattern can not control or injection of imperfect type of remaining oil-rich sand bodies, but also because of its large number, and has considerable residual oil reserves, so its tapping potential in the oil field And oilfield geological research is of great significance.