Abstract The ionic composition of produced water from four oil producing chalk fields in the Danish North Sea has been interpreted to shed light on the temporal and regional variations in the water composition. The data includes 8749 samples, covering 157 wells, analyzed for eight ions. The data dates back to the start of production (1972–2007) and the most recent data is from 2015. The variations are viewed in a regional context with respect to subsurface geology, fluid migration and production strategy since parts of the fields have been extensively water flooded by injection of seawater. We present results from both time series analysis and from multivariate statistical methods and show that produced water across the four fields, up to 55 km apart, show gradual changes in the composition reflecting regional scale hydrodynamics as well as subsurface geology. We use multivariate statistical analysis to extract end-member compositions to facilitate comparison between basins and for an evaluation of scale and corrosion risk. The data analysis shows five main water types. These are mainly differentiated by salinity and the concentrations of the divalent cations. The study is discussed in the context of examination of interconnection between close-lying fields including aquifer support and distribution of principal ions associated with corrosion and scale formation.

中文翻译：

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丹麦北海白垩岩地层水类型的分类和变化：Halfdan、Dan、Kraka 和 Valdemar 油藏研究

摘要 丹麦北海四个产油白垩油田产出水的离子成分已被解释为揭示水成分的时间和区域变化。数据包括 8749 个样品，覆盖 157 个孔，分析了八个离子。数据可以追溯到开始生产（1972-2007 年），最近的数据来自 2015 年。 由于部分油田已被广泛使用，因此在地下地质、流体运移和生产策略方面的区域背景下看待这些变化通过注入海水淹没的水。我们展示了时间序列分析和多变量统计方法的结果，并表明四个油田的采出水相距达 55 公里，显示反映区域尺度流体动力学和地下地质的成分的逐渐变化。我们使用多元统计分析来提取端元成分，以促进盆地之间的比较以及水垢和腐蚀风险的评估。数据分析显示了五种主要水类型。它们主要通过盐度和二价阳离子的浓度来区分。该研究是在检查邻近油田之间的相互联系的背景下进行讨论的，这些油田包括含水层支持以及与腐蚀和水垢形成相关的主要离子的分布。它们主要通过盐度和二价阳离子的浓度来区分。该研究是在检查邻近油田之间的相互联系的背景下进行讨论的，这些油田包括含水层支持以及与腐蚀和水垢形成相关的主要离子的分布。它们主要通过盐度和二价阳离子的浓度来区分。该研究是在检查邻近油田之间的相互联系的背景下进行讨论的，这些油田包括含水层支持以及与腐蚀和水垢形成相关的主要离子的分布。