松辽盆地三肇凹陷葡萄花油层河控浅水三角洲沉积模式

Sedimentary Mode of Shallow Lacustrine Fluvial-Dominated Delta of Putaohua Reservoirs in the Sanzhao Depression,Songliao Basin

利用22口井的岩芯资料和近4000口井的录井、测井及生产动态资料,系统分析了三肇凹陷葡萄花油层河控浅水三角洲沉积特征和沉积模式。研究揭示该三角洲体系骨架砂体为大量、密集(平均分布密度1.02支/km)、窄的(多为200～300m)水下分流河道砂体,砂体连续且水下延伸较远,直至消失变成薄的席状砂,河口坝砂体不发育且呈明显的河控性(位于水下分流河道两侧及前方,呈顺源窄带状)。在深入认识三肇凹陷葡萄花油层的沉积背景、沉积特征及沉积相类型等基础上,建立了葡萄花油层的沉积模式——河控浅水三角洲沉积模式,又进一步建立了6种亚相区沉积模式,即:河控浅水三角洲前缘亚相外前缘区"浪控席状砂"模式、河控浅水三角洲前缘亚相内-外前缘过渡区"水下分流河道末端河控席状砂"模式、河控浅水三角洲前缘亚相内前缘区"河控河口坝"模式、河控浅水三角洲前缘亚相内前缘区"河控带状体"模式、河控浅水三角洲前缘-分流平原过渡区"近岸"模式和河控浅水三角洲分流平原亚相"河控带状体"模式。这为本区储层空间分布模式建立、骨架成因单砂体识别及油田进一步挖潜与调整提供了坚实的地质依据。

Based on 22 well cores,4000 logging data and initial potential data,sedimentary characteristics and mode of shallow lacustrine fluvial-dominated delta of Putaohua reservoirs in Sanzhao sag,Songliao basin were analyzed. It is realized that submerged distributary channel sandbodies as sand body framework of this delta system is abundant,closely and narrow. It is continual than original understanding and it extends to the far underwater,until disappearing into thin sheet sands. Debouch bar sands is not well preserved and is fluvial-dominated. Based on understanding of sedimentary background and sedimentary characteristics and sedimentary facies types of Putaohua reservoirs in Sanzhao sag,sedimentary mode of shallow lacustrine fluvial-dominated delta is established,and sedimentary mode of six subfacies is further divided. Shallow lacustrine fluvial-dominated delta outer front is mode of tide-dominated sheet sand; Transition region of inner front and outer front is mode of fluvial-dominated sheet sand; Inner front is mode of fluvial-dominated debouch bar and mode of fluvial-dominated banding; Transition region of front distributary plain is mode of inshore;Delta distributary plain subfacies is mode of fluvial-dominated banding.It provides the solid geological basis for the establishment of spatial distribution pattern of reservoir,identify the causes of mainly monosandbody and further tapping the potential of oil field.