Cement to Safeguard the Wells Integrity in Underground Hydrogen Storage: an Experimental Investigation

Abstract

Eni, like all the Energy companies, aims to accelerate the reduction of its carbon footprint by implementing the best applicable low-carbon solutions, and hydrogen is surely playing a fundamental role. Hydrogen is the simplest and most abundant element on the planet and an energy vector that has shown great promise worldwide as a solution for meeting climate challenges. This is because it can store and supply large quantities of energy without producing CO2 emissions during combustion. Once produced, the hydrogen needs to be stored for later consumption and here it becomes clear that the importance of Underground Hydrogen Storage (UHS) rises significantly. The main goal of any company is to find all the possible synergies with current activity and business. Even though injection in salt caverns has unquestionable benefits, hydrogen injection in depleted oil and gas reservoirs could be the solution to maximize efficiency and implement a circular economy approach. From an engineering point of view, before developing any Underground Hydrogen Storage (UHS) project, the first step is to analyze and study all the challenges related to this activity. Well suitability must be guaranteed during all the reinjection, in the following document a detail of this topic and especially of one of the main elements that have the role to safeguard the integrity of the well, which is the cement. This document aims to analyze the interaction of standard cement slurries used in oil and gas fields with hydrogen at standard reservoir conditions. The cement-hydrogen interaction tests shown in this document were conducted using autoclave as key instrumentation to simulate reservoir temperature and pressure conditions. The tests were designed and conducted using the methodological approach typical of the materials/fluids compatibility tests. Preliminary autoclave experimentation results show that hydrogen does not alter the chemical and physical characteristics of cement samples. This compatibility study of hydrogen is the first important step to further de-risk activities, the assurance of well integrity is critical and important in all stages to avoid any loss uncontrolled of hydrogen.