疏松砂岩油藏冷冻岩心与常规岩心相渗曲线研究

为了更好地评价疏松砂岩油藏的水驱开发特点,针对实际油藏地质和流体性质特征,用室内水驱油非稳态法,研究近似油藏条件下冷冻岩心与常规岩心的油水相渗曲线,并进行对比分析。在数据处理过程中,利用JBN经验公式法进行计算,采用对数函数对其进行拟合与回归,最后绘出油水相渗曲线,并作为判断水驱效果的依据。结果表明,水驱后冷冻岩心的残余油饱和度平均为29%,残余油饱和度对应的水相相对渗透率为0.32,驱油效率平均为52%;常规岩心的残余油饱和度平均为30%,残余油饱和度对应的水相相对渗透率为0.30,驱油效率平均为52%。同一含水饱和度所对应的冷冻岩心,其水相相对渗透率高于常规岩心所对应的水相相对渗透率,但常规岩心见水时间早于冷冻岩心,且含水上升较快。冷冻岩心的最终水驱油效率和无水采收率均高于常规岩心。

Study on relative permeability curves of frozen core and conventional core in unconsolidated sandstone reservoir

In order to better find out the development characteristics of unconsolidated sandstone reservoir, aiming at the geologic features and the fluid property characteristics of reservoir, nonsteady state method to study the relative permeability curves of oilwater of frozen rock and eunventional core is proposed under the conditions of similar reservoirs with water displacing oil in laboratory which are compared. JBN empirical formula is adopted in the process of data processing, using the logarithm function for fitting and regressing calculation to gain the oil-water relative permeability curves, which obtains the experimental resuh. The resuh shows that residual oil saturation of frozen core is 29% on average alter water flooding, water relative permeability of corresponding with residual oil saturation is 0.32, oil displacement efficiency averages 52%. Residual oil saturation is 30% on average for conventional core, water relative permeability of corresponding with residual oil saturation is 0.30 and oil displacement efficieney of an average is 52%. Water permeability of frozen core of corresponding witb same water saturation is larger than that of conventional core, but water breakthrough time of c, onventional core generally predates that of frozen core, and water cut rises quickly. Ultimate water flooding efficiency of frozen core and breakthrough reeovery are higher than those of conventional core.