Study Explores Wellbore-Integrity Challenges in the Era of Energy Transition

_ This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 225550, “Wellbore-Integrity Challenges in the Era of Energy Transition,” by Taofik H. Nassan, SPE, and Mohammed Amro, SPE, TU Bergakademie Freiberg. The paper has not been peer-reviewed. _ The energy transition introduces novel challenges to well integrity that remain largely unexplored and unaddressed. In this paper, wellbore integrity from a traditional standpoint is revisited and examined against emerging requirements driven by energy-transition applications. The work consolidates common wellbore-integrity issues across various energy-transition applications, offering a unified perspective based on a literature review and the authors’ extensive laboratory experience. It highlights critical challenges and proposes future research directions to address the evolving needs of subsurface operations in the energy-transition era. Energy Transition and New Wellbore Fluids New challenges exist for wellbore integrity because of the unique properties of newly introduced fluids and developing operational aspects. Hydrogen (H2). H2 is the smallest molecule in nature and is highly penetrative and reactive. Compared with CO2 and methane, it can more easily diffuse through most geological formations. Only rock salt and crystalline rock formations can effectively contain hydrogen. At standard conditions, hydrogen has a density eight times lower than that of methane, allowing it to rise quickly in the atmosphere. In terms of reactivity, H2 reacts with a wide range of materials, including water, oxygen, and metals. This high reactivity increases the vulnerability of infrastructure exposed to hydrogen, raising the risks of corrosion, leakage, and other integrity issues. Moreover, hydrogen is more flammable than methane, with the potential for fires that are more difficult to extinguish. Another problem associated with H2 is metal embrittlement. Molecular H2 can dissociate into hydrogen ions, which then diffuse into the alloy, accumulating at defects or grain boundaries. CO2. CO2 has been commonly used in enhanced oil recovery (EOR) for decades. However, most CO2 currently injected for EOR purposes is sourced from natural deposits. In contrast, CO2 from anthropogenic sources may contain different impurities. CO2 also reacts with elastomers used in well completions. Underground CO2 storage is a relatively new technology and is expected to serve as a key bridge toward a net-zero emissions future. Water. Water is the primary fluid used in geothermal energy extraction. However, emerging trends in geothermal technologies are exploring greater depths and novel concepts, which may alter water composition and worsen traditional issues such as mineral precipitation and corrosion. Wellbore Integrity in Emerging Geoenergy and Geostorage Systems Geological Carbon Storage (GCS). In the presence of water, CO2 is reactive and can form carbonic acid, which can degrade both cement and casing materials. Additionally, CO2 is expected to be stored permanently in various geological formations. Consequently, the standards for casing and cement materials currently used in the petroleum industry may need to be revised. Extensive testing is required to assess their suitability for long-term GCS applications.