基于近井壁自然电位的大庆油田水淹储层地层水电阻率计算方法

地层水电阻率的准确求取一直是制约大庆油田特高含水期水淹层剩余油饱和度计算的难点,采用常规自然电位曲线求取地层水电阻率效果很差。通过理论推导阐明了井眼径向自然电位的分布机理,通过对比实验改进测量方式,得到受井眼影响更小、分辨率更高的近井壁自然电位曲线;结合大庆油田储层普遍存在过滤电位的实际情况,通过岩石物理实验确定新过滤电位模型的相关参数,并以此校正自然电位,实现了当前地层水电阻率的求取,通过与水分析资料对比,效果良好,验证了该方法的可靠性。

Algorithm of Formation Water Resistivity in Water-out Reservoirs in Daqing Oilfield Based on Near Borehole Spontaneous Potential Data

Accurate calculation of formation water resistivity is always difficulty in the calculation of remaining oil saturation in water flooded layer of Daqing oilfield.The formation water resistivity calculated from conventional spontaneous potential curves is very poor.Through theoretical derivation,the distribution mechanism of the borehole spontaneous potential is calibrated.By means of contrast test,it is obtained the spontaneous potential curves of near borehole wall,which is smaller and has higher resolution.Combining with the actual situation of Daqing oilfield with reservoir filtration potential,relevant parameters of new filtration potential model is determined by rock physics experiments,and the spontaneous potential is corrected to achieve the current formation water resistivity calculation.Compared with water analysis data,the effect is good,the reliability of the method was verified.