Heterogeneity Of Braided River Reservoirs In The Lower Reaches Of Guantao Formation In Chengdong West Area And Its Effect On Remaining Oil Distribution

Chengdong Oilfield is located in the south of Zhanhua Depression Chengzi mouth raised,the internal Cheng 21 is normal fault control,divided into East and West District.After years of development,the current oil field into the high water phase,reservoir production decline,leading to people’s understanding of oil-water relationship is unclear.In view of the above problems,it is necessary to carry out the study of reservoir heterogeneity,analyze the oil and water distribution of the block,and provide the basis for the study of the remaining oil distribution.Through this study,the following results were achieved:(1)Based on the study of core observation and laboratory analysis data,the Ng8,Ng9 and Ng10 sand layers in the lower reaches of the study area are braided river sediments based on petrography and logging curves.And gravel sandstone-based,less mud,the overall size of coarse.By plotting the sandbody profile,the study section has typical sand-mud deposition characteristics in the section,and the vertical sand body overlay and lateral stacking are widely developed.(2)Analysis of reservoir heterogeneity through three layers,layers and planes:positive rhythm and complex rhythm in the layer,more common mudy mezzanine and physical interlayers,heterogeneity strong;Layer and permeability.The heterogeneity of Ng8~4-Ng9~1 and Ng9~3-Ng10~1 is the most obvious.The plane heterogeneity is mainly affected by sand body size,sedimentary microfacies and permeability The heterogeneity of the sedimentary microfacies is different,and the microfacies of the central beach are the best,and the heterogeneity is the weakest.The micro-physical properties of the river are poor and the heterogeneity is strong.(3)Combining with the research results of reservoir heterogeneity,the influencing factors of remaining oil distribution were analyzed and analyzed,and the distribution of residual oil in the layer was affected by rhythm and interlayer.The stratigraphic heterogeneity leads to the complex relationship between oil and water in the vertical direction,and the non-permeable barrier is blocked,so that the corresponding intervals The residual oil is enriched at different positions.On the plane,the residual oil is enriched by the microstructures and the distribution of the different sand bodies.