动静结合方法计算储层水淹后地层混合液电阻率技术及其在剩余油饱和度解释中的应用——以吉林扶余油田泉四段油层为例

针对国内注水开发油田水淹层测井解释中地层混合液电阻率(Rz)难以确定的问题,提出了一套动静结合确定Rz的新技术。该技术以开发井投产初期含水率资料为基础,结合静态研究成果,反演投产层的地层混合液电阻率(Rz),进而标定井筒中泥浆滤液电阻率(Rmf),在此基础上,应用自然电位测井的基本原理,可以计算垂向上各层的地层混合液电阻率(Rz)。对于初期投产层为单层和多层两种情况,提出了一种迭代算法,均能实现Rz的反演和Rmf的准确标定。以该技术为基础,针对已经进入高含水阶段的扶余油田泉四段油层开展水淹层测井资料的二次解释。通过与密闭取心检查井岩心分析数据对比,剩余油饱和度误差平均为6%。

A new technique of the determination of mixed fluid resistivity in water flooded formation by combining dynamic and static information and its application to well logging interpretation of residual oil saturation: an example from Quan 4 formation of Fuyu oilfield

For the water flooded oil field,the well log interpretation of water flooded formation is very important.The mixed fluid resistivity in water flooded formation(Rz)is a key interpretation parameter that is difficult to be determined.This paper presents a new technique for computing Rz by combining the dynamic and static data.This technique utilizes the water content data of production well at initial stages and inverses them to get the mixed fluid resistivity,and then calibrates the resistivity of mud filtrate(Rmf)in the borehole.Based on the result from above mentioned process and utilizing the basic theory of spontaneous potential log,we can determine the mixed fluid resistivity of all zones in the vertical profile of the well.By using an iterative algorithm,this technique can be applied to the cases that the production zone at initial stage is either a single-layer or multi-layers.As an example,this technique was applied to the Quan 4 formation of Fuyu oilfield that has entered the high water-cut stage.The well log data in water flooded formation in this area was re-interpreted for residual oil saturation.The computed oil saturation was compared with the sealed coring analysis data and the average error of saturation is 6%.