Deepwater Ghana Abandoned and Suspended Wells Monitoring and Verification Process; A Basis for Prevention of Future Unwanted Environmental Leakages of Wellbore Fluids

Abstract

Abstract In the new oil province of Ghana, numerous deep water exploration and appraisal wells have accumulated over recent years, particularly since the first major oil discovery in 2007. Different operators have been involved and different technical standards applied in Well suspension and/or abandonment mainly to suit company requirements and individual well circumstances. In the meantime, government and environmental regulators have been working with operators to determine what legislative framework is needed in Ghana to underpin these important environmental requirements; the key criteria being safely abandoned or suspended wells that will not leak hydrocarbons or other wellbore fluids to shallow formations and/or the marine environment in the very long term. This paper discusses the process used by one major operator in Ghana to verify and monitor the status of suspended and abandoned wells. It will also discuss how considerations around well integrity are managed right from the design stage through to construction, production and abandonment phases. It is a process that has evolved with industry best practice. It is based on international standards and involves third party independent well examination as a key component. Important well integrity concepts such as the ‘ownership’ of legacy wells and the dangers of ‘orphan wells’ are considered. A specific example of well abandonment in Ghana is briefly discussed and the key documentation underpinning a Well integrity management system is demonstrated. To date the system can be said to be effective since no environmental leaks have been recorded though the true test will be for future generations to review this environmental record 100 years from now. Some information from this paper was previously presented at the SPE Applied Technical Workshop Accra during April 2015 "Assuring Well Integrity in a Diverse Environment".