Integrity of completion systems for subsurface hydrogen storage

The objective of this project is to quantify the risks associated with storing hydrogen in underground storage facilities by gaining a better understanding of the physical and chemical mechanisms and transport properties involved in porous systems. Through laboratory tests, the effect of compressed hydrogen interacting with reservoir water within the pores of the completion cement is studied experimentally, quantifying the relevant parameters in water-saturated cements under real reservoir conditions. Hydrogen diffuses rapidly in various materials, being partially stored in the microstructures, leading to changes such as hydrogen embrittlement in metals. Less is known about the behavior of hydrogen in cement, especially in the presence of formation water. Under reservoir conditions, a fluid phase boundary develops, resulting in the formation of capillary pressure, which in fine-pored systems can reach high magnitudes that may contribute to the system’s tightness. The resulting capillary pressures are confirmed by determining the interfacial tension between the fluids and the contact angle formed in the pores under realistic operating conditions using pendant and sessile drop measurements. The findings on the governing mechanisms, along with data on the diffusivity of hydrogen inside the pores filled with formation water, are used to estimate hydrogen loss using empirical correlations and numerical simulations.