The development of low-carbon energy may spur the usage of depleted gas fields for hydrogen storage. However, such a solution is fraught with deformation risk for steel columns of the underground wells, as well as hydrogen conversion into hydrogen sulfide by bacteria living in these reservoirs. In addition, rock minerals reacting with hydrogen can significantly transform porosity and permeability of the formation because of which it is recommended that H2 be stored in sands and sandstones without admixtures of clays and carbonates.
To avoid the risks, the scientists of Perm Polytech and the Institute of Oil and Gas Problems of the Russian Academy of Sciences have developed a program allowing a detailed examination of core samples before and after exposure to hydrogen: they used 20 core samples taken from the depth of just under 1,500 meters and analyzed the samples’ properties and chemical composition before exposure to hydrogen, and then placed them into a cylinder with inlet and outlet holes for H2 supply carried out over seven days using a compressed hydrogen cylinder. During the last step, the scientists evaluated condition of the modified cores.
The experiments showed that after exposure to H2, the porosity and permeability of the core decreased by 4.6% and 7.9%, respectively. Hydrogen reduced the strength of intergranular contacts, which weakened the rock. However, since hydrogen is much more mobile than natural gas, this reduction in properties is unlikely to have a significant impact on H2 injection and recovery.
“Based on these results, we can say that the reservoir under study is chemically resistant to hydrogen due to a large amount (96.64%) of silicon oxide in the samples. In this case, silicon oxide does not interact with hydrogen,” Perm Polytechnic quotes Sergey Popov, Doctor in Engineering, head of the laboratory of the Institute of Oil and Gas Problems of the Russian Academy of Sciences.
