Abstract: 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,permeabilities and mercury intrusion capillary porosimetry of cores, the lower limits of prosity and permeability of shale oil reservoirs in different depths (778~890、959~1070、1378~1478、2093~2200 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.

Key words: lower limit of prosity and permeability, argillaceous dolomite, shale oil, Xingouzui Formation, Jianghan Basin