鄂尔多斯盆地中部吴仓堡地区长61低阻油层成因分析

Mechanisms Analysing of Low Resistivity Oil Layer, of Chang 61 in Wuchangbao, Middle Region of Ordos Basin

鄂尔多斯盆地中部吴仓堡地区长61储层油层与水层电阻之比小于2,给测井解释带来一定困难。以大量岩石物理实验和生产数据为基础,将储层地质特征与地球物理特性相结合,从岩石特征、泥质含量、黏土类型、不动水饱和度、油水分异作用及地层水矿化度等方面,分析了吴仓堡油区长61油藏低阻的地质影响因素。该区油层低阻的控制因素以岩性因素、不动水饱和度及高地层水矿化度为主,泥质含量、黏土类型及油水分异作用为辅。根据低阻油层地球物理响应特征,引入三参数来降低岩性对储层电阻率的影响,建立低阻油层流体识别图版,生产应用效果显著,为后续储层评价奠定基础。

It is difficult to interpret the formation as the rate of oil resistance and water resistance is less than 2 in Wuchangbao, central part of Ordos Basin. Based on a plant of the rock physics experiments and production data, we ana- lyzed the geologic factors of the Chang61 oil formation of Wuchangbao from the lithology, shale, clay types, immovability water saturation, oil-water separation affect, water salinity and so on. We thought main causes of low resistivity are the lithol- ogy, immovability water saturation and water salinity. The secondary causes are shale, clay types, oil/water separation affect. Referred to geologic feature and geophysical signature, we used three parameters to reduce the impact of the introduction of the reservoir rock resistivity, expanding fluid properties to establish low resistivity reservoir fluid identification plates. The production and application of the effect is significant, and lay the foundation for subsequent reservoir evaluation.