Investigation on efficiency and security improvement on injection of supercritical carbon dioxide into rock.

二氧化碳的地下封存是减少温室气体对地球影响的最有前景和最现实的方法。为了实现这一工程，必须了解注入CO2在岩石中的行为。本研究以CO2为压裂液，对花岗岩试件进行了水力压裂试验。结果表明，由于CO2的低粘度，CO2比水更容易诱发三维裂纹和更广泛的裂纹扩展。研究结果表明，CO2水力压裂可形成有效裂缝，用于页岩气开采和干热岩地热开采，同时实现CO2的地下封存。

The underground sequestration of Carbon dioxide (CO2) seems to the most prospective and realistic method of reduce the greenhouse gas effect on the earth. To realize the project, it is necessary to understand behavior of injected CO2 in rock. In this research, we made hydraulic fracturing experiments in granite specimens using CO2 as fracturing fluid. The results indicate the tendency that CO2 induces more three dimensionally and widely spreading cracks than water due to its low viscosity. The results suggest that hydraulic fracturing using CO2 can generate efficient cracks for shale gas productionand hot dry rock geothermal extraction, with realizing the underground sequestration ofCO2 at the same time.