Abstract: The research of microcosmic mechanism and geologic origin of low-resistivity layers in continental reservoir of Jiyang Depression showed that microcosmic factors for reducing apparent resistivity of oil layer included mainly high-salinity formation water of reservoir, additive conductivity of shale in reservoir and development of fine pores of reservoir. In order to determine the electric conductivity of matrix in some electric conductive minerals, the resistivity of some dry cores in this area were measured. The results of experiment showed that electric conductive minerals were not enough to form matrix electric conduction network independently and could not show extremely electric conductive property. Therefore their influence on the resistance of reservoir was very weak. The formation of low-resistivity layers was closely related to sedimentary system, sediment sources and its evolvement, diagenesis and structural faults. The favorable development zones of low-resistivity layers are mainly the reservoirs in the sedimentary environment of drought salted lake basin, the reservoir upwards 1000 meters of basin edge, the slump fan of the delta front, the deepwater turbidite fan and steep slope fan front of base of middle Es₃, top of Es₃ and base of Es₂, reservoir of Es₃ and Es₂ nearby faults and capable of trapping high-salinity formation water of deeper layer.

Key words: Jiyang Depression, continental reservoir, low-resistivity layers, microcosmic mechanism, geologic origin

摘要： 对济阳坳陷陆相储层低电阻率油层的微观形成机理及地质成因的研究表明,引起油层视电阻率降低的微观因素主要有:①储层含高矿化度的地层水;②储层所含粘土的附加导电;③储层微孔隙发育。为了验证导电矿物骨架的导电性,测量了干岩样的电阻率。实验结果表明,导电矿物不能独立形成完整的导电网络,未表现出极强的导电能力,因此对储层的电阻影响极小。低电阻率油层的形成与沉积体系、沉积物源及其演化史、成岩作用、构造断裂等因素密切相关。干旱咸化湖盆沉积环境下的储层、盆地边缘1 000m以上的储层、沙三中下部及沙三上和沙二下的三角洲前缘滑塌扇、深水浊积扇、陡坡扇的扇端、靠近沟通深部大断层能够“俘获”深部高矿化度地层水的沙三、沙二段储层是低电阻率油层的有利发育区带。

关键词: 济阳坳陷, 陆相储层, 低电阻率油层, 微观机理, 地质成因