Advancing knowledge on fugitive gas migration from integrity compromised energy wells

Abstract

Decommissioned oil and gas wells can suffer integrity failure and release fugitive gases into the environment. This typically occurs unnoticed since post-abandonment monitoring is uncommon. To reach NetZero, methane emissions from fugitive sources such as decommissioned wells, must be mitigated increasing the need for research on this emerging issue. This research aimed to advance knowledge on this topic through three main thrusts. First, by evaluating the integrity of decommissioned wells in the field, finding no signs of integrity failure and highlighting a need for standardised assessment methods. Next, by identifying sedimentary rock properties controlling fugitive gas migration in the shallow subsurface of an area of extensive hydrocarbon development, finding flow will occur through units with low total displacement pressure, or through preferential pathways. Finally, by evaluating data from an airborne methane survey to better understand the incidence rate of well integrity failure and identify well attributes related to its occurrence, finding a 5% failure rate and that well operator, well type, abandonment years, completion type, surface casing vent flow and remedial treatments reported may be linked to integrity failure. Overall, this study will aid in developing effective fugitive gas monitoring and detection strategies, establishing emission targets and identifying parameters involved in development of well integrity failure.