Chang Haiqing, Liu Teng, He Qiping, Li Duo, Crittenden John, Liu Baicang
College of Architecture and Environment, Sichuan University, No. 2 Section 2 Chuanda Road, Chengdu 610207, China and Institute of New Energy and Low Carbon Technology, Sichuan University, Chengdu, Sichuan 610207, China E-mail:
Chuanqing Drilling Engineering Company Limited, Chinese National Petroleum Corporation, Chengdu, Sichuan 610081, China.
Water Sci Technol. 2017 Jul;76(3-4):575-583. doi: 10.2166/wst.2017.237.
Shale gas has become a new sweet spot of global oil and gas exploration, and the large amount of flowback water produced during shale gas extraction is attracting increased attention. Internal recycling of flowback water for future hydraulic fracturing is currently the most effective, and it is necessary to decrease the content of divalent cations for eliminating scaling and maintaining effectiveness of friction reducer. Zeolite has been widely used as a sorbent to remove cations from wastewater. This work was carried out to investigate the effects of zeolite type, zeolite form, activation chemical, activation condition, and sorption condition on removal of Ca and Mg from shale gas flowback water. Results showed that low removal of Ca and Mg was found for raw zeolite 4A and zeolite 13X, and the efficiency of the mixture of both zeolites was slightly higher. Compared with the raw zeolites, the zeolites after activation using NaOH and NaCl greatly improved the sorption performance, and there was no significant difference between dynamic activation and static activation. Dynamic sorption outperformed static sorption, the difference exceeding 40% and 7-70% for removal of Ca and Mg, respectively. Moreover, powdered zeolites outperformed granulated zeolites in divalent cation removal.
页岩气已成为全球油气勘探的新热点，页岩气开采过程中产生的大量返排液受到越来越多的关注。目前，将返排液内部循环用于未来的水力压裂是最有效的方法，并且有必要降低二价阳离子的含量以消除结垢并保持减阻剂的有效性。沸石已被广泛用作从废水中去除阳离子的吸附剂。开展这项工作是为了研究沸石类型、沸石形态、活化化学品、活化条件和吸附条件对从页岩气返排液中去除钙和镁的影响。结果表明，天然4A沸石和13X沸石对钙和镁的去除率较低，两种沸石的混合物效率略高。与天然沸石相比，用氢氧化钠和氯化钠活化后的沸石大大提高了吸附性能，动态活化和静态活化之间没有显著差异。动态吸附优于静态吸附，钙和镁去除率的差异分别超过40%和7%-70%。此外，粉状沸石在去除二价阳离子方面优于粒状沸石。
