Abstract In this study, the oil recovery potential of seawater (SW), SW with different ion compositions, low-salinity seawater (LSSW), and formation water (FW), is investigated, using chalk reservoir cores and crude oil from the North Sea. Furthermore, the impact of temperature on SW flooding performance is addressed. A series of flooding experiments were conducted at reservoir conditions (2800 psi and 60 °C), followed by spontaneous imbibition tests. Secondary SW and FW flooding led to the same oil recovery. Tertiary SW injections, performed after secondary FW flooding and secondary LSSW injection, did not lead to any extra oil recovery at 60 °C. Injecting SW at 100 °C did not lead to additional recovery either. Spiking the SO 4 −2 content of SW by four times, at 60 °C, did not show any additional oil production as well as increasing the concentration of Ca +2 and the Ca +2 /Mg +2 ratio at 60 °C. Conversely, tertiary LSSW injection, after secondary SW injection, led to 2.5% OOIP additional oil recovery. More importantly, secondary LSSW injection, compared to the secondary SW and FW injection, led to around 8% OOIP extra oil recovery. Consistently, the results of the imbibition test showed the same trend: tertiary LSSW imbibition, after secondary SW imbibition, led to 4.25% OOIP extra oil recovery. This study, through employing chalk reservoir cores and crude oil, reveals that LSSW flooding in examples of silica containing chalk reservoirs in the North Sea, has a better oil recovery potential compared to both SW and FW flooding. This is in contrast to other published results as it will be discussed in the paper.

中文翻译：

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一种量化北海白垩油藏海水和低盐度海水注入采油潜力的综合实验方法

摘要 本研究利用白垩岩油藏岩心和北海原油，研究了海水 (SW)、不同离子成分的 SW、低盐度海水 (LSSW) 和地层水 (FW) 的采油潜力。 . 此外，还讨论了温度对 SW 驱油性能的影响。在储层条件（2800 psi 和 60 °C）下进行了一系列驱油实验，然后进行了自吸测试。二次 SW 和 FW 驱导致相同的石油采收率。在二次 FW 驱油和二次 LSSW 注入之后进行三次 SW 注入，在 60 °C 下没有导致任何额外的石油采收率。在 100 °C 下注入 SW 也不会导致额外的回收。在 60 °C 下将 SW 的 SO 4 -2 含量增加四倍，没有显示出任何额外的石油产量以及在 60°C 下增加 Ca +2 的浓度和 Ca +2 /Mg +2 比率。相反，三次 LSSW 注入，在二次 SW 注入之后，导致 2.5% OOIP 额外的石油采收率。更重要的是，与二次 SW 和 FW 注入相比，二次 LSSW 注入导致约 8% 的 OOIP 额外采油。始终如一地，渗吸测试的结果显示出相同的趋势：三次 LSSW 渗吸，在二次 SW 渗吸之后，导致 4.25% 的 OOIP 额外石油采收率。本研究通过使用白垩岩油藏岩心和原油，揭示了北海含二氧化硅白垩油藏实例中的 LSSW 驱油与 SW 和 FW 驱相比具有更好的采油潜力。这与其他已发表的结果形成对比，因为它将在论文中讨论。