吴起地区长61油层黏土矿物对油层低电阻率化的影响

为了认识黏土矿物对油层低电阻率化的影响,以薄片、扫描电镜、X射线衍射、测井解释和试油结果为依据,对吴起地区长61油层黏土矿物特征及其对电阻率的影响进行了研究。结果表明,黏土矿物对低电阻率油层的形成具有控制作用,具体表现在3个方面:第一为附加导电作用,以网状伊/蒙混层矿物最强,是油层电阻率降低的关键因素;第二为对孔隙结构的改造,导致束缚水饱和度增高,电阻率降低,以伊利石最为明显;第三是对水分子的吸附作用,以绿泥石等为主。综合三者的作用大小和矿物含量,吴起地区黏土矿物对电阻率的影响程度依次为:伊利石>伊/蒙混层>绿泥石>高岭石。此项研究可对低电阻率油层的存在机理和分布进行有效解释和预测。

Effect of clay minerals on low resistivity of Chang 6_1 reservoir in Wuqi area

In order to understand the effect of clay minerals on low resistivity reservoirs,the slice,scanning electronic microscope,X-ray diffraction,logging interpretation and oil testing results were applied to study the effect of clay minerals on resistivity of Chang 61 reservoir in Wuqi area.The result shows that clay minerals play a dominate role on the forming of low resistivity reservoir.The role displays in the following three aspects： the role mainly is additional conductivity,and it is strongest in the illite/smectite mixed layer and is the key factor for resistivity decline;followed by the pore structure reformation which caused the bound water saturation increasing and resistivity decline,and it is most in illite;and then the absorption of water molecule which is mainly in chlorite.By considering the effects and mineral content,it was believed that the order of effect of clay minerals on resistivity is： illite illite/semectite mixed layer chlorite kaolinite.This study result can be used to interpret the mechanism and predict the distribution of low resistivity reservoir.