苏北盆地溱潼凹陷低阻油气层成因研究

低阻油气层是一种非常规储层,其油气层电阻率与邻近水层电阻率接近,或有时低于水层的电阻率.试油证实在苏北盆地溱潼凹陷阜宁组阜三段存在着低电阻率油气层,但其成因机理一直没有得到很好的认识.应用扫描电子显微镜、X-射线衍射等现代化实验技术,对其储层岩石学特征、粘土矿物类型、含量及分布、孔隙结构特征、地层水矿化度等方面进行深入研究.研究表明形成溱潼凹陷阜宁组阜三段储层低阻的原因是:高束缚水饱和度、粘土附加导电性、高地层水矿化度.根据形成低阻油层的地质条件分析及导电机理研究认为,对于低阻油层的测井解释评价,应主要针对高含束缚水成因的低阻油层,在评价方法上应主要考虑采用"双水模型";对于低阻油层的分布预测,应考虑在沉积相的弱水动力沉积区寻找低阻油层的富集分布.

Genesis of Low-resistivity Reservoirs in Qintong Sag, Subei Basin

The resistivity of low-resistivity reservoirs is usually close to or sometimes lower than that of ad-jacent water-bearing zones. It is verified by testing that low-resistivity pay zones exist in the third member of the Funing Formation of the Qintong sag, but their mechanism and genesis are not clear. Based on such modern laboratory techniques as scanning electronic microscope and X-ray diffraction, the lithologic char-acteristics, the types, content and distribution of clay minerals, pore texture, the salinity of formation wa-ter of the reservoir are fully researched. The study shows that high bound water, the additional conductiv-ity, and high salinity of formation water result in low-resistivity pay zones of the third member of the Fu-ning Formation. Based on the geologic condition and conductive mechanism of the low-resistivity reservoir, logging interpretation and evaluation should be aimed at the type caused by high irreducible water satura-tion, and the "dual water model" should be used to evaluate it. For prediction of low-resistivity reservoirs distribution, the weakly hydrodynamic sediment area is favorable for the main enrichment.