Monitoring Elastic Parameters Changes during Underground Hydrogen Storage Using Rock Physics Parametrized FWI

Seasonal storage of hydrogen produced from renewable energy can become one of the key strategies tomeet the high energy demand of today’s society. The most suitable sites for seasonal hydrogen storageare depleted gas fields. This study proposes a workflow based on the integration of full-waveforminversion (FWI), rock physics modeling (RPM) and gas property modeling for monitoring changes inelastic medium parameters due to hydrogen injection. A rock physics model including the Gassmannequation and fluid mixing laws has been implemented, which accurately links rock physical propertiesto elastic properties. The parameterized approach is based on optimizing fluid saturation to reducecrosstalk between model parameters during the inversion process, while simultaneously providing aquantitative estimation of the fluid within the reservoir. The synthetic models show that parameterizedinversion produces higher accuracy and fewer artifacts than conventional FWI. Our results underscorethe importance of an appropriate RPM to reflect real subsurface conditions and proper fluid mixinglaws. Therefore, FWI parameterization provides an efficient technique for monitoring hydrogen storagesites in depleted gas fields to ensure efficient storage.