基于孔隙结构研究的密闭取心饱和度校正方法

低渗透储层的油、水过渡带往往较大,可动流体通常为油、水两相,在常压密闭取心时,发生降压脱气,油、水两相均有减少,导致密闭取心饱和度求取困难。生产中通过蒸发实验对此进行校正,而未进行蒸发校正的区块往往导致昂贵的密闭取心资料的浪费。通过采用一种不需要进行蒸发实验的低渗透储层密闭取心饱和度校正方法,即根据储层品质指数与密闭取心饱和度的散失量有良好的相关性,利用储层品质指数对储层进行分类,对不同类型的孔隙结构储层的校正系数进行研究,以获取不同的校正系数。经分析化验和生产动态数据验证,该方法对低渗透储层原始含油饱和度求取有较好的效果。因此将未作蒸发实验的密闭取心资料充分利用,获得了准确的原始含油饱和度,为测井解释饱和度提供了对比标准。

Method of sealed coring saturation correction based on pore structure

Low permeability reservoirs always have a thicker oil-water transitional zone,while mobile fluid usually is in form of tow-phase flow.Therefore,water and oil saturation will decrease undergoing the release of pressure and outgassing as the process of sealed coring,which results in the difficulty in acquiring oil saturation of sealed core.In practice,evaporation experiments were used to correct it,however,data of laboratory of sealed core will be wasted when there is no evaporation experiment.There is a method which can correct the sealed core saturation of low permeability reservoirs with no evaporation experiment.First of all,classify the reservoir types according to reservoir quality index based on fairly well relationship between reservoir quality index and the fluid loss rate of sealed coring.Then study the correction factor of different types of reservoirs to obtain different correction factors.According to the analysis of laboratory and production data,it is proved that the correction method for obtaining initial saturation of low permeability reservoirs based on pore structure classification is effective.So the valuable sealed coring data with no evaporation experiment can be made use for obtain initial saturation,and provide criterion for logging interpretation.