鄂尔多斯盆地侏罗系低对比度油层判识方法

鄂尔多斯盆地侏罗系发育大量低对比度油层,具有含油层系多、地层水变化大、油层特征多变、油水关系复杂的特征。综合运用地质、测井、化验分析及试油等资料,从储层特征、水性、电性及相渗分析入手,侏罗系低对比度油层的主控成因是地层水变化大,导致测井电阻率低对比度和特殊相渗关系引起低饱和度低对比度,核心问题是储层含油饱和度的准确评价和储层相渗关系主控因素的测井表征。提出电阻率增大率—孔隙度交会、相渗等效产水率含油饱和度下限这2种有效油水识别方法,有效解决了侏罗系低对比度油层判识的难题,在生产应用中解释符合率明显提高,见到良好地质效果。

Fluid Identification Method of Low Contrast Reservoirs in Jurassic of Ordos Basin

There are a large number of low contrast reservoirs in Jurassic of Ordos basin,which are characterized by many oil-bearing series,great changes in formation water,variable reservoir characteristics and complex oil-water relationship.Synthesizing geological,logging,chemical analysis and oil testing analysis data,based on the analysis of reservoir characteristics,water property,electric property and phase permeability,it is clear that the main controlling cause of low contrast reservoir in Jurassic is the low contrast of logging resistivity caused by the great change of formation water and the low contrast of low saturation caused by the special phase permeability relationship.The key problem is the accurate evaluation of reservoir oil saturation and the reservoir logging characteristics of the main controlling factors of the relationship between the formation and permeability.Based on this,two effective oil-water identification methods are putting forward,cross plot of resistivity index and porosity,as well as lower limit of oil saturation calculated from water production rate in terms of relative permeability,respectively.They can effectively solve the problem of identification of low contrast reservoir in Jurassic system.The consistency between log interpretation and actual production results is significantly improved.