This work is part of the Aquifer CO₂-Leak project and aims to understand, quantify and model the environmental impact of a CO₂ leak on water quality in the carbonate freshwater aquifer as well as CO₂-water-carbonate interactions. The experiment has been performed within an Oligocene carbonate underground quarry located in Saint-Emilion (France).

A water charged with dissolved CO₂ was injected in the aquifer through a borehole. Downstream, seven wells were fitted with in-situ probes which automatically measured physicochemical parameters. Periodic water samplings in all wells have been undertaken to determine the elemental concentrations by ion chromatography.

The spread of CO₂ in the groundwater was monitored as a function of time and was observed to influence the various physicochemical parameters. Five parameters seem to be excellent indicators for monitoring a gas plume during CO₂ geological storage in regard to our results: electrical conductivity and pH, and Ca²⁺, HCO₃⁻, and CO_2(aq) concentrations.

The interaction between CO₂ and limestone is highlighted by a saturation index (SI) calculated with PhreeqC software. It shows (i) a slight trend to dissolution of calcite in the injection well (SI < 0) linked to the reaction process between CO₂-H₂O-CaCO₃ and (ii) a transport process via diffusion for the observation wells with a SI≃0.

The evolution of physicogeochemical signatures in the aquifer allows us to understand the reactive and transport processes that occur during the migration of a gasified water plume in the context of leakage from a geological storage reservoir. Our results will make possible to model a leakage in a complex natural reservoir.

这项工作是Aquifer CO ₂泄漏项目的一部分，旨在了解，量化和建模CO ₂泄漏对碳酸盐淡水含水层中水质以及CO _2-水-碳酸盐相互作用的环境影响。该实验是在位于法国圣埃米利翁的渐新世碳酸盐岩地下采石场进行的。

通过钻孔将充有溶解的CO _2的水注入含水层中。在下游，七口井装有自动测量理化参数的原位探针。已经对所有井进行了定期的水采样，以通过离子色谱法测定元素浓度。

监测CO ₂在地下水中的扩散与时间的关系，并观察到其对各种理化参数的影响。五个参数似乎是出色的指标CO期间监测气体羽流₂关于我们的结果地质储存：电导率和pH值，和Ca ²⁺，HCO ₃ ^-和CO _{2（水溶液）}的浓度。

用PhreeqC软件计算的饱和指数（SI）突出显示了CO ₂和石灰石之间的相互作用。它显示（i）方解石在注入井中溶解的趋势很小（SI <0），这与CO ₂ -H ₂ O-CaCO ₃之间的反应过程有关；以及（ii）扩散通过观察井进行的扩散过程。 SI≃0。

含水层中物理地球化学特征的演变使我们能够了解在地质储层泄漏的情况下，气化水烟流迁移过程中发生的反应和传输过程。我们的结果将可能为复杂的天然油藏中的渗漏建模。