The Dominant Factors And Distribution Characteristics Of Effective Reservoirs Of Upper Palaeozoic Erathem In Dongpu Depression

Many years exploration practice in Dongpu Depression reveals that there exists relatively active oil and gas showing in upper-Paleozoic.Depend on the status quo of exploration degree and low level of acquaintance degree,through observation and description of cores,identification of thin sections,analysis of mercury injection data,and interpretation of well logging data,combined with regional structure-burial history,maturity of organic matter and palaeogeothermal,this thesis discussed sediment features,petrological characteristics,physical properties,diagenesis process and diagenetic evolution of upper-Paleozoic reservoirs in Dongpu Depression,also it studied the main controlling factors,standard of classification evolution and distribution characteristics of effective reservoirs.Researches show that in upper-Paleozoic of Dongpu Depression,Shiqianfeng Formation mainly deposited fluvial facies,upper Shihezi Formation mainly deposited delta facies-plane subfacies,lower Shihezi Formation mainly deposited delta facies-front subfacies,Shanxi Formation mainly deposited barrier coastal facies,Taiyuan Formation and Benxi Formation mainly deposited carbonate platform facies and barrier coastal facies.C lastic rock reservoir is the most important kind of reservoirs in the study area,and Shihezi Formation and Shiqianfeng Formation are likely to develop effective reservoirs.Lithic arkose of upper-Paleozoic reservoirs in Dongpu Depression is the main rock type,and sorting degree is medium to good.Correlation between porosity and permeability is relatively good.The average porosity value is around 5.86%,and the average permeability value is around 0.15×10^-3?m²,so the whole reservoirs belong to extremely low porosity with extremely low permeability reservoir.The reservoir space is mainly secondary porosity.Main diagenesis includes compaction,cementation,metasomatism and dissolution,and diagenetic stage is mainly between stage A to B of the middle diagenetic phase.The three control factors affecting reservoir physical properties of the study area are sedimentary facies,petrological characteristics and diagenesis,and among them sedimentary facies is the most important one.Upper-Paleozoic sandstone reservoirs in Dongpu Depression can be divided into high quality reservoir,medium reservoir,poor reservoir and dense layer.High quality reservoir is mainly distributed in the west slope of west sub-sag and Zhuaying area.Medium reservoirs are mainly distributed in Dongmingji areas,Mao 4 Wells area,the central uplift belt,and C hangyuan area.Poor reservoirs are mainly distributed in Sanchunji area.In these areas,Wenliu-Weicheng area and Huzhuangji-Qingzu area develop effective reservoirs.