印度尼西亚方程的改进及其在大庆长垣低孔渗储层的应用

Application of improved Indonesia saturation equation in low porosity and permeability reservoirs in Daqing Placanticline

针对大庆长垣F油层储层具有孔隙度小、渗透率低、泥质含量高、微孔隙发育、束缚水饱和度高等特点,通过理论和实验分析长垣F油层低孔、低渗储层的主要导电因素,得出泥质附加导电和束缚水导电是该区F油层的低孔、低渗泥质砂岩储层的重要导电因素.考虑束缚水和可动水导电路径不同,基于三水导电模型的推导原理,建立混合水等效电导率方程;依据该区矿化度较低和含泥高的储层特征,对适用于淡水高泥储层的印度尼西亚方程进行改进,用混合水等效电导率代替原方程中的地层水电导率,建立长垣地区F油层低孔低渗泥质砂岩含水饱和度模型.利用岩心分析数据和常规测井资料,采用多元回归法确定长垣F油层饱和度模型中的泥质体积分数、孔隙度、束缚水饱和度.利用岩电实验数据,采用最优化方法确定长垣F油层饱和度模型中的饱和度指数、胶结指数等参数.经密闭取心井含水饱和度对比和试油结果验证,建立的含水饱和度模型可用于F油层的低孔低渗泥质砂岩储层定量评价.

In F formation of Daqing placanticline,analysis result of reservoir characters has shown that the formation has low porosity,low permeability,high shale content,more microscopic capillary pore and high irreducible water saturation.The main factors of rock conductance in low porosity and permeability reservoirs are analyzed from theoretically and experimentally.The result shows that conductivity of the reservoirs is mainly influenced by excessive conductivity of shale and irreducible water.Considering the differences of conductance paths between the free water and irreducible water,and based on derivation rules of three-water conduction theory,an equivalent conductivity equation of mixed water is established.Indonesia saturation equation,once applied in reservoirs with fresh water and high shale content,is considered to be improved,since the salinity of the formation water is low and shale content is high in F formation.By replacing water conductivity in Indonesia saturation equation with mixed water equivalent conductivity,a new water saturation model for low porosity and permeability shaly sand reservoirs in Daqing placanticline is established in this paper.The parameters of interpretation model including shale content,porosity,irreducible water saturation etc.are determined by multiple regression method with core analysis data and log data.The saturation exponent and cementation exponent in the model are determined from core experimental data with an optimization technology.Compared with well test results and core analysis water saturation in sealed coring well,the results show that the new saturation equation can be applied in evaluation of low porosity and permeability shaly sand reservoirs in F formation with good precision quantitatively.