Wei Ji

Gas field produced water has traditionally posed significant challenges for oil and gas enterprises due to its complex chemical composition, stringent environmental protection requirements, and lack of effective utilization channels. The surging demand for lithium carbonate, driven by the rapid growth of the new energy vehicle market, has shifted the focus to the development of lithium recovery technologies from produced water, making it a key area of research in resource utilization. This work established a systematic research framework for the optimization of the pretreatment process, the screening of the lithium extraction process efficiency, and the selection of adsorbent materials based on the low-grade lithium-containing characteristic (with lithium mass concentrations below 50 mg/L) of the gas field produced water in Changqing Jingbian. The synergistic pretreatment of flocculation precipitation and ozone catalytic oxidation demonstrated remarkable efficacy, achieving a turbidity removal rate of over 90% and a COD reduction of 43%. Although the screening results of lithium extraction processes exhibited that the electrochemical lithium extraction process had a low lithium recovery rate and suffered from side reactions and instability, the manganese-based adsorbent coupled with multistage membrane separation and concentration process could stably achieve a lithium recovery rate of over 80%, demonstrating that the adsorption method for lithium extraction possesses significant technical superiority. Based on the promising laboratory research results, an integrated sled mounted device with a processing capacity of 200 L/h was deployed for on-site testing. The average lithium-ion adsorption recovery rate reached 81%, and the purity of the lithium carbonate product reached 99.2%, surpassing the requirements of the GB 11075-2013 Grade 0 standard requirements. This study innovatively established a comprehensive processes system for lithium extraction from low-grade lithium-containing gas field produced water, achieving three significant technological breakthroughs: optimization of complex produced water pretreatment process, development of high-performance manganese-based adsorbents, and the successful integration of skid-mounted equipment. These advancements provide both theoretical support and practical guidance for the large-scale development of lithium resources from gas field produced water, paving the way for sustainable resource utilization and environmental protection in the oil and gas industry.

Co-author/s:

Jialin Wang, PetroChina Changqing Oilfield.