松辽盆地南部腰英台油田低阻油层的成因及识别

低电阻率油气层是一类电性上比较特殊的油气层,由于在测井结果中不易与水层区分,故被作为一类重要而特殊的油层进行研究。腰英台油田青山口组油层是低电阻率油层,作者分别在勘探和开发阶段通过地质和地球物理方法对其进行了深入的研究。结果表明,引起腰英台油田青山口组低阻油层的主要因素是岩性、岩石结构和地层,直接原因是:存在储层砂岩颗粒细、粘土含量高、孔隙结构复杂引起的高束缚水;较为富集的分散状黄铁矿在油层中形成电子导电网络降低了油层的电阻率;油层中砂泥岩薄互层中的泥岩夹层抑制了砂岩层感应测井响应。对低阻油层的判断可能由于各地区地质特征的不同而采用的方法有所不同;青山口组低阻油层主要是通过地质试验技术、可动水饱和度、自组织特征映射等方法确认的。

Origin and Recognition of the Low Electric-Resistance Oil Layer in the Yaoyingtai Oil Field, Southern Songliao Basin

The low electric-resistance oil layer is a special and important kind of oil layer with similar electric-resistance to that of the water layer.Through the geological and geophysical study on the oil layer of the Qingshankou Formation of the Yaoyingtai Oil Field during the petroleum exploration and development,it is indicated that the low electric-resistance of the Qingshankou Formation oil layer was caused due to lithological and texture features of the stratum.It is believed that the fine grain size,high contents of clays,complicated porous texture of the host sandstone of the Qingshankou Formation,which was formed in the front delta environment,resulted in the high water-bearing capability which caused low electric resistance of the host rock.Relatively rich disseminated pyrite in oil-bearing layer also decreased the electric resistance of the host rock.The mudstone layers laminated within the oil-bearing sandstone reduce the response of the electric signal of the measurement.All above factors directly caused the low electric-resistance of the oil-hosting rock of the Qingshankou Formation.In general,different methods are applied to define the low electric resistance oil layer due to geological features in various regions.However,low electric resistance oil layer of the Qingshankou Formation of the Yaoyingtai oil field was defined through geological testing technique,mobile water saturation and reflection features of self-organization methods.