Combination types and accumulation effect of hydrocarbon migration channels in middle-shallow layers of northern belt in Dongying sag

By using formation pressure and fluid potential, combined with the variation regularity of crude oil density and formation water salinity, the dominant direction of oil and gas migration from Guantao formation to the third member of Shahejie formation in the northern belt of Dongying sag was determined. In the middleshallow layers, there are mainly three kinds of oil and gas migration channels: faults, sand bodies and unconformities, which can form three combination types: sand body-fault-sand body type, fault-sand bodyunconformity type, and fault-unconformity type. These combination types play a very important role in the oil and gas accumulation in the study area. On the one hand, they control the oil and gas migration model and form the anti "Z" front model and stepladder model. On the other hand, they control the spatial distribution characteristics of oil and gas. The fault-sand body-unconformity type and sand body-unconformity type determine that the oil and gas in Zhengjia-Wangzhuang area has the characteristics of "multi-layer system distribution, various types of oil and gas reservoirs, and long migration distance", while the single type of sand body-fault-sand body combination determines that the oil and gas in Shengtuo and Shanjiasi areas has the characteristics of "single type of oil and gas reservoir and short migration distance".