Costs for CO₂ capture could be reduced if CO₂ gas impurities can be co-injected and do not adversely affect the long-term CO₂ containment. This project, as a part of the Callide Oxyfuel Project, investigates the geochemical impacts of the CO₂ impurities SO₂ and O₂ on mineral-fluid reactions in a siliciclastic reservoir. In a single-well push-pull field experiment CO₂-saturated water with and without impurities was injected into the reservoir. The injection water was allowed to interact with minerals in the reservoir for three weeks, during which water was back-produced and sampled on three occasions. Four soluble tracers were added to the injection water to estimate the proportions of injection and formation water in the back-produced water. Redox state, speciation and reaction pathway modelling are used as part of the data interpretation. Once injected, SO₂ (67 ppm vol/vol, initially as a dissolved impurity in CO₂) was dissolved and oxidised, leading to sulphate formation. The alkalinity of the injection water counteracted any substantial decrease in pH, which would otherwise occur due to sulphuric acid formation, thus inhibiting additional mineral dissolution. After being injected, O₂ (6150 ppm vol/vol, dissolved impurity in CO₂) led to immediate oxidative dissolution of pyrite. Consequently, the SO₄²⁻ concentration increased rapidly and dissolved iron is predicted to precipitate as hematite. Overall, the impact of CO₂ impurities was minimal.

如果可以共注入CO ₂气体杂质并且不会对CO ₂的长期围产产生不利影响，则可以降低CO ₂捕集的成本。作为Callide含氧燃料项目的一部分，该项目研究了CO ₂杂质SO ₂和O ₂对硅质碎屑岩储层中矿物流体反应的地球化学影响。在单井推挽式野外实验中，CO ₂将有杂质和无杂质的饱和水注入到储层中。注入水被允许与储层中的矿物质相互作用三周，在此期间，水被回采并进行了三次采样。将四种可溶性示踪剂添加到注入水中，以估算回采水中注入水和地层水的比例。氧化还原状态，物种形成和反应途径建模被用作数据解释的一部分。注入后，SO ₂（67 ppm vol / vol，最初是在CO _2中的溶解杂质）被溶解并被氧化，导致形成硫酸盐。注入水的碱度抵消了pH的任何大幅降低，否则会由于形成硫酸而发生pH降低，从而抑制了额外的矿物质溶解。注入后，O ₂（6150 ppm vol / vol，在CO _2中溶解的杂质）导致黄铁矿立即氧化溶解。因此，SO ₄ ^2-的浓度迅速增加，并且溶解的铁预计会以赤铁矿的形式沉淀。总体而言，CO ₂杂质的影响最小。