东海盆地西湖凹陷平北北部地区平湖组储层成岩相分析

Study on diagenetic facies of reservoir of Pinghu Formation in the northern Pingbei area of the Xihu Depression,East China Sea Basin

成岩相与储层物性关系密切,通过识别优势成岩相可以预测储层“甜点”分布,为油气滚动勘探开发提供依据。针对东海盆地西湖凹陷平北北部地区古近系平湖组储层,应用铸体薄片鉴定、储层参数二维与三维交会等方法,结合测试参数等特征,进行储层成岩相分析。结果表明:平湖组储层经历压实、胶结、溶蚀等成岩作用,形成低孔中低渗储层。储层划分为致密压实相、碳酸盐胶结相、黏土矿物充填相和不稳定组分溶蚀相4种成岩相类型,通过选取自然伽马(GR)、密度(DEN)、声波时差(AC)等测井曲线,建立成岩相测井参数解释模型,定量确定成岩相与储层物性的关系,确定不稳定组分溶蚀相为优势成岩相,与含油气性及产能测试匹配性良好。

The study on diagenetic facies provide the basis for predicting the vertical distribution of reservoir“sweet spots”.Diagenetic facies were studied through casting thin sections,two-dimensional and three-dimensional intersection of reservoir parameters,combined with the production test parameters of Pinghu reservoir in the northern Pingbei area of the Xihu Depression,East China Sea Basin.Results show that the pore spaces in the Pinghu reservoir predominantly belong to micron-scale pore through diagenesis like compaction,cementation,dissolution,etc.Pinghu reservoir has low porosity and medium-low permeability.Pinghu reservoir can be divided into four diagenetic facies,which are dense compaction,carbonate cementation,clay mineral filling and unstable component dissolution facies to analyze the relationship between the four diagenetic facies and open flow capacity parameters.Several logging curves are selected to establish log interpretation model,among which are gamma ray(GR),density(DEN)and acoustic interval transit times(AC),etc.It is determined that the unstable component dissolution facies of unstable components is the dominant diagenetic facies.The matching relationship between the diagenetic facies,hydrocarbon character and open flow capacity parameters is good,especially for unstable component dissolution facies.