Jackson Matthew D, Al-Mahrouqi Dawoud, Vinogradov Jan
Department of Earth Science and Engineering, Imperial College London, UK.
Petroleum Development Oman, Muscat, Oman.
Sci Rep. 2016 Nov 23;6:37363. doi: 10.1038/srep37363.
Laboratory experiments and field trials have shown that oil recovery from carbonate reservoirs can be increased by modifying the brine composition injected during recovery in a process termed controlled salinity water-flooding (CSW). However, CSW remains poorly understood and there is no method to predict the optimum CSW composition. This work demonstrates for the first time that improved oil recovery (IOR) during CSW is strongly correlated to changes in zeta potential at both the mineral-water and oil-water interfaces. We report experiments in which IOR during CSW occurs only when the change in brine composition induces a repulsive electrostatic force between the oil-brine and mineral-brine interfaces. The polarity of the zeta potential at both interfaces must be determined when designing the optimum CSW composition. A new experimental method is presented that allows this. Results also show for the first time that the zeta potential at the oil-water interface may be positive at conditions relevant to carbonate reservoirs. A key challenge for any model of CSW is to explain why IOR is not always observed. Here we suggest that failures using the conventional (dilution) approach to CSW may have been caused by a positively charged oil-water interface that had not been identified.
实验室实验和现场试验表明，通过在一种称为控制盐度注水（CSW）的采油过程中改变注入盐水的成分，可以提高碳酸盐岩储层的原油采收率。然而，人们对CSW的了解仍然很少，并且没有预测最佳CSW成分的方法。这项工作首次证明，CSW过程中的提高采收率（IOR）与矿物-水界面和油-水界面处的zeta电位变化密切相关。我们报告了一些实验，其中CSW过程中的IOR仅在盐水成分变化在油-盐水界面和矿物-盐水界面之间诱导出排斥性静电力时才会发生。在设计最佳CSW成分时，必须确定两个界面处zeta电位的极性。本文提出了一种新的实验方法来实现这一点。结果还首次表明，在与碳酸盐岩储层相关的条件下，油-水界面处的zeta电位可能为正。任何CSW模型面临的一个关键挑战是解释为什么并非总能观察到IOR。在这里，我们认为使用传统（稀释）方法进行CSW失败可能是由于未识别出带正电的油-水界面所致。
