Japanese Scientists Develop New Fracking Method: Extracting Shale Gas Using CO2
A Kyoto University research team developed a new basic technology to extract shale gas trapped deep underground by injecting carbon dioxide into shale bedrock instead of water, The Yomiuri Shimbun has learned.
The research team said it plans to start a large-scale substantiative experiment to verify the technology in autumn, aiming for practical use of the technology within several years.
In addition to securing shale gas, a new energy resource, the newly developed technology is also expected to help combat global warming as it will confine CO2 underground.
A common method to extract shale gas is to frack hard shale bedrock by injecting pressurized water into shale formations. The more finely cracked the bedrock is, the more shale gas can be obtained. However, making ideal cracks in shale formations by injecting water is difficult because the liquid has a high viscosity.
According to the research team led by Kyoto University Prof. Tsuyoshi Ishida and Assistant Prof. Chen Youqing, CO2 becomes a “supercritical” fluid if it is heated to 31.1 C or more and subjected to pressure of at least 73 atmospheres. A supercritical fluid is very smooth and has properties midway between a liquid and gas.
The research team confirmed that supercritical CO2 injected into shale bedrock fractured the bedrock and created finer cracks more widely in comparison to the use of pressurized water.