Phenomenon analysis of oil/water inversion in Shawan formation of Junggar basin

Oil-water relationship in Neogene Shawan formation of Chunfeng oilfield is relatively complex,with co- existence of normal edge-bottom water and water inside reservoir,which means that in the same reservoir,when high position drilling water layer,the lower parts presenting oil/water inversion phenomenon,which affects the overall understanding and reservoir evaluation.The analysis results indicate because of the reservoir differences in vertical plane,and property differences between the underwater distributary channel and distributary channel of delta,reservoir pore throat capillary force changes,namely the poorer physical properties,the bigger reservoir pore throat capillary force.In addition,the heavy crude oil density is larger,which reduces the original filling power.The above mentioned reasons lead to complex oil-water relationship in this area.