大庆油田储层自然电位曲线的变异与孔隙压力解释

Variation of natural potential curves and interpretation of pore pressure in Daqing oilfield reservoir

随着大庆油田的不断开发,其储层的自然电位与开发初期相比在幅度和形态上均发生了较大变化,构成自然电位的扩散吸附电位和过滤电位的主次地位也发生了转变。造成这种变化的原因在于长期注水后储层中流体矿化度和流体压力的剧烈变化。利用过滤电位和压差的相关性可以对储层的压力状态进行判别并对孔隙压力的大小进行比较精确地解释。据此总结出一种适用于解释砂岩油藏注水开发后期孔隙压力的方法——自然电位法。

Along with development of Daqing oilfield, the amplitude and configuration of natural potential of reservoir took place large variation in comparison with that in the initial stage of development, the change of the master-slave position of diffusion absorption potential and filtration potential constituted natural potential also took place. The reasons resulted in these variations lay in sharp variation in fluid salinity and fluid pressure of reservoir after long-period water injection. The pressure state of reservoir could be judged and size of pore pressure could be precisely interpreted by using the correlation of filtration potential with differential pressure. In view of the above, it summed up a method that is suitable to interpret pore pressure of sandstone reservoir in the later stage of water flood recovery, which is called natural potential method.