Swapping Water for CO2 Could Make Fracking Greener and More Effective

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Swapping Water for CO2 Could Make Fracking Greener and More Effective

Scientists at the Chinese Academy of Sciences and China University of Petroleum (Beijing) have demonstrated that CO2 may make a better hydraulic fracturing (fracking) fluid than water.

Their research, published May 30 in the journal Joule , could help pave the way for a more eco-friendly form of fracking that would double as a mechanism for storing captured atmospheric CO2.

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Fracking is a technique used to extract resources from unconventional reservoirs in which fluid (usually water mixed with sand, foaming agents, biocides, and other chemicals) is injected into the rock, fracturing it to release the resources within. Of the approximately 7-15 million liters of fluid injected, 30%-50% remains in the rock formation after extraction ends. Its high water consumption, environmental risks, and frequent production issues have led to concerns about fracking among both industry experts and environmental advocates.

"Non-aqueous fracturing could be a potential solution to circumvent these issues," says Nannan Sun , a researcher in the Shanghai Advanced Research Institute at the Chinese Academy of Science s. "We chose CO2 fracturing from a range of options because the process includes multiple benefits. However, we were still lacking a fundamental understanding of the technology, which is greatly important for its further development and deployment."

Benefits of CO2 fracturing include eliminating the need for a hefty water supply (which would make fracking viable in arid locations), reducing the risk of damage to reservoirs (as often happens when aqueous solutions create blockages in the rock formation), and providing an underground repository for captured CO2.

However, CO2 is not likely to become commonly used as a fracking fluid unless it is more effective than water at resource production. To investigate the differences between CO2 and water as fracturing fluids on a microscopic level, Sun and his team collected shale outcrops from Chongqing, China and fractured them with both fluids. They found that CO2 outperformed water, creating complex networks of fractures with significantly higher stimulated volumes.

Read the full article on Science Daily

Reference : Xuehang Song, Yintong Guo, Jin Zhang, Nannan Sun, Guofei Shen, Xin Chang, Weisheng Yu, Zhiyong Tang, Wei Chen, Wei Wei, Lei Wang, Jun Zhou, Xiao Li, Xiaofeng Li, Jinhui Zhou, Zhenqian Xue. Fracturing with Carbon Dioxide: From Microscopic Mechanism to Reservoir Application. Joule, 2019; DOI: 10.1016/j.joule.2019.05.004

Source: Cell Press

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