CO2 Injection and Storage - Qualification of Well Barriers in Adjacent Wells

Abstract

The Petroleum industry needs a common industry practice related to design of adjacent CO 2 injection wells and plugging & abandonment of CO 2 injection wells. Adjacent wells are defined in this paper as wells that can be exposed to the injected CO 2 . A CO 2 injection reservoir may be penetrated by a number of adjacent wells that can be potential leakage sources. These wells can be abandoned-, production-, injection-and disposal wells. Adjacent wells can have well integrity issues that can lead to leakage of CO 2 to the surroundings. The paper presents some of the potential reservoir-and wellbore-related leakage pathways.Seismic surveys are performed to verify how the CO 2 medium moves within the reservoir. There are identified challenges related to the verification methods of the structural integrity and how the CO 2 medium is spread within the CO 2 injected reservoir. This can have an impact with regards to the well integrity and degradation of the construction of the adjacent wells.Carbon dioxide can occur in the liquid, solid or gas phase depending on temperature and pressure. When the pressure containment of a well is lost, the carbon dioxide can have phase changes which can lead to very low temperatures in the wellbore. This paper presents the challenges related to qualification and testing of well barrier elements related to low temperatures and the exposed medium.The paper illustrates the industry need to further consentrate on well integrity related to CO 2 injection wells as well as to the adjacent wells. The control of barrier status is a crucial HSE factor to avoid major incidents caused by i.e. unintentional leaks and well control situations. Knowledge of well integrity status at all times enables the companies to take the right actions in a proactive manner and thereby prevent incidents.