Boone Pickens School of Geology, Oklahoma State University, Stillwater, OK 74078, USA.
J Contam Hydrol. 2020 Aug;233:103600. doi: 10.1016/j.jconhyd.2020.103600. Epub 2020 Jan 3.
Experimental results on barium transport in dolomite are used to formulate, calibrate, and validate a reactive transport model of produced water disposal into dolomite saline aquifers. The model accounts for sorption, dissolution/precipitation reactions of minerals (dolomite, calcite, barite, gypsum, and witherite) and complexation and acid-base reactions of most abundant ionic species (H, HCO, SO, Ca, Mg, and Cl) in produced waters including Ba which is the most common and abundant heavy metal present in produced water from oil and gas reservoirs. The model is applied to determine the chemical controls of barium transport in Arbuckle dolomite aquifers. The simulated scenario corresponds to produced water disposal through a Class II injection well located near an abandoned well that can facilitate the transport of barium to underground sources of drinking water (USDW). Simulation results reveal that most suitable dolomite aquifers to prevent the contamination of USDW by barium are dolomite aquifers of high SO content (>1000 mg/L). The mobility of barium which is promoted by the formation of Ba(Cl) and competition of cations (Ca and Mg) for hydration sites of dolomite can be suppressed by the precipitation of barium as barite in dolomite saline aquifers of high SO content. A sensitivity analysis conducted using a two-level factorial design of experiments indicates that barium transport can be controlled by the initial concentration of a single ionic specie (mostly SO) or the concentration of various ionic species (e.g., SO, Cl, and Mg). This depends on the chemical composition of both the dolomite saline aquifer and injection produced water. This work highlights the potentiality of a reactive transport simulation approach to conduct compatibility analysis of dolomite saline aquifers and produced waters to select dolomite aquifers and/or decide on treatment methods to prevent the contamination of USDW by barium.
实验结果表明，白云岩中的钡运移可以用来制定、校准和验证一个关于采出水在白云岩咸水含水层中的处置的反应性运输模型。该模型考虑了吸附作用、矿物（白云石、方解石、重晶石、石膏和菱锶矿）的溶解/沉淀反应以及大多数丰富离子物种（H、HCO、SO、Ca、Mg 和 Cl）的络合和酸碱反应，这些离子物种存在于采出水中，其中钡是油气储层采出水中最常见和最丰富的重金属。该模型用于确定钡在阿巴克尔白云岩含水层中的运移的化学控制因素。模拟情景对应于通过位于废弃井附近的 II 类注水井处置采出水，这可以促进钡向地下饮用水源（USDW）的迁移。模拟结果表明，SO 含量较高（>1000mg/L）的白云岩含水层最适合防止 USDW 受到钡的污染。形成 Ba(Cl)和阳离子（Ca 和 Mg）对白云石水合位点的竞争促进了钡的迁移，但在 SO 含量较高的白云岩咸水含水层中，钡可以作为重晶石沉淀，从而抑制钡的迁移。使用两水平析因实验设计进行的敏感性分析表明，钡的运移可以通过单一离子物种（主要是 SO）的初始浓度或各种离子物种（如 SO、Cl 和 Mg）的浓度来控制。这取决于白云岩咸水含水层和注入采出水的化学成分。这项工作突出了反应性运输模拟方法在进行白云岩咸水含水层和采出水的相容性分析方面的潜力，以选择白云岩含水层和/或决定处理方法，防止钡对 USDW 的污染。
