鄂尔多斯盆地中部长63段致密砂岩储层石油有效充注物性下限

Determination of lower limit of effective oil filling property of Chang 63 member tight sandstone reservoir in central Ordos Basin

储层物性下限确定是有效储层判别的重要依据,目前,试油结果统计法、压汞参数法、累计储层能力丢失法是确定储层物性下限最为常用的方法,但是,这些方法缺少成藏动力条件对储层物性下限的约束.为此,将实验数据与测井资料充分结合,估算烃源岩的生烃强度、泥岩剩余压力,综合考虑成藏动力、储层物性及其相互匹配关系,确定不同成藏动力条件下的储层物性下限.研究表明:(1)测井多参数回归法、神经网络法均可较为准确的计算白豹地区长7段烃源岩有机碳含量;(2)研究区烃源岩生烃强度主要介于(150~350)×10^(4)t/km^(2)、剩余压力4~18 MPa,根据成藏动力条件,可划分为强成藏动力、中等成藏动力、弱成藏动力三种类型;(3)成藏动力越大,对应的储层物性下限值越低,强成藏动力条件对应孔隙度、渗透率有效充注下限分别为6.0%、0.08×10^(-3)μm^(2);中等成藏动力条件对应有效充注孔隙度、渗透率下限分别为7.8%、0.11×10^(-3)μm^(2);弱成藏动力条件对应有效充注孔隙度、渗透率下限分别为8.7%、0.15×10^(-3)μm^(2).

Determination of the lower limit of reservoir physical property is an important basis for effective identification of reservoir.At present,statistical method of oil test results,mercury injection parameter method and cumulative reservoir capacity loss method are the most commonly used methods to determine the lower limit of reservoir physical property.However,these methods lack the constraints of reservoir dynamic conditions on the lower limit of reservoir physical property.Therefore,the experimental data and well logging data are combined to estimate the hydrocarbon generation intensity and mudstone residual pressure of source rock,and the lower limit of reservoir physical property under different accumulation dynamic conditions is determined by considering the accumulation dynamics,reservoir physical property and their matching relationship.The results show that:(1)Both the multi-parameter regression method and the neural network method can accurately calculate the organic carbon content of source rock of Chang 7 member in Baibao area.(2)The hydrocarbon generation intensity of source rocks in the study area is mainly(150~350)×10^(4) t/km^(2),and the residual pressure is 4~18 MPa.According to the dynamic conditions of accumulation,the source rocks can be divided into three types:strong accumulation power,medium accumulation power and weak accumulation power.(3)The higher the accumulation force is,the lower the corresponding lower limit of reservoir physical property is.The lower limit of porosity and permeability under strong accumulation force condition are 6.0%and 0.08×10^(-3)μm^(2),respectively.The lower limits of porosity and permeability are 7.8%and 0.11×10^(-3)μm^(2),respectively.The lower limits of porosity and permeability are 8.7%and 0.15×10^(-3)μm^(2),respectively.