Reduction potentials and abatement costs for methane emissions associated with compromised wellbore sealing systems in Russian oil wells

Abstract

The growth of methane concentration in the atmosphere affects climate change (United States Environmental Protection Agency (EPA), 2021). Methane has a global warming potential over100 years that is 25 times higher than Carbon dioxide (CO2) per ton gas released (Forster & Ramaswamy, 2007). About 60% of global methane emissions are coming from human activities, including oil and gas, which contributes 33% (United Nations Economic Commission for Europe (UNECE), 2021). Methane emissions are possible across the whole supply chain of the oil and gas industry, from oil exploration to the end-user. This study focuses on the emission group in the oil upstream segment, associated with the well's failed sealingsystem. The first objective of this report is to assess the possible reduction of methaneemissions associated with failures of the well's sealing system in those cases where repair is technically feasible. The second objective is to evaluate the required costs for implementing such measures in the context of additional expenses for each produced ton of oil.Several chapters of the study introduce the reader to the term well integrity, explaining the basic principles of the well construction process and the possible causes of integrity failures.Emissions reduction estimation requires several parameters, and some are not available (e.g.,not measured), such as the share of the oil wells in Russia with integrity issues. Therefore,experts with vast experience in Russia's oil and gas industry were surveyed to fill the informational gaps and determine the required parameters.The study discovers that it is possible to reduce methane emissions associated with the well'sintegrity issues by 78 kt CH4 a year, representing 17% of the category "Oil and venting" from the oil upstream segment in Russia (462 kt CH4 per year as of 2017). Additional costs would be required to restore the integrity of wells in Russia to mitigate methane emissions estimates as 3 US$ per ton of oil produced. Well integrity restoration has a double positive implication.The positive effect on climate change by methane emissions reduction. Additionally, the oilproducers would also benefit from the integrity restoration due to the extended life of the well,and increased of oil production. Therefore, targeting oil wells' integrity to reduce methaneemissions could be quick to implement and relatively low-cost solution for methane emissionsreduction in the oil upstream segment.