江汉盆地新沟嘴组页岩油储层物性下限

Lower limits of porosity and permeability of shale oil reservoirs in the Xingouzui Formation,Jianghan Basin

江汉盆地新沟嘴组泥质白云岩层系钻获页岩油，开辟了该地区油气勘探的新领域。弄清区内页岩油富集与分布规律，对有效储层物性下限的研究具有重要意义。根据研究区岩心实测孔隙度、渗透率和高压压汞资料，综合应用经验统计法、压汞曲线法和最小流动孔喉半径法，确定了江汉盆地南部新沟嘴组不同深度段（778—890，959～1070，I378-1478，2093-2200m）的页岩油储层物性下限，并建立了物性下限值与深度的相关性方程。结果表明：不周研究方法确定的物性下限值不同。总体上，压汞曲线法和最小流动孔喉半径法确定的物性下限值较高，经验统计方法确定的物性下限值较低。随着储层埋深的增加，不同方法确定的物性下限之间的差异减小。多种方法综合运用能够降低物性下限的不确定性。研究区页岩油储层物性下限值随着深度的增加逐渐降低，其中孔隙度下限值随着深度的增加呈指数函数递减，渗透率下限值随着深度的增加呈幂函数递减。

Shale oil resources found in the argillaceous dolomite in the Xingouzui Formation of the Jianghan Basin has opened up a new domain for petroleum exploration. The study on the lower limit of prosity and permeability of effective reservoirs is significant to reveal accumulation and distribution of shale oil in the Basin. According to the porosities, per- meabilities and mercury intrusion capillary porosimetry of cores, the lower limits of prosity and permeability of shale oil reservoirs in different depths （778 -890,959 - 1 070,1 378 -1 478,2 093 - 2200 m） in the Xingouzui Formation in the southern part of the Basin were determined using the empirical statistics, mercury curve and minimal pore throat radius methods. Moreover,the relationships between the lower limits and depths were established. The preliminary findings of this study include the followings ： （ 1 ） the lower limits determined by the different methods are various ; （2） the lower limits determined by the mercury curve and minimal pore throat radius are greater, while that determined by the empirical statistic method are smaller; （3） the errors of lower limits obtained from the different methods decrease with increasing depths, so that a variety of methods should be used to reduce the uncertainty of the lower limits. The lower limits of shale oil reservoirs in the study area reduce with the increase of depths. The lower limits of porosity （permeability） decrease with increasing depth in an exponent （power exponent） manner.