LAUSR

Abstract In the absence of a gas market, the management of associated gas (AG) often poses a serious challenge to the development of oil fields, resulting in potentially stranded gas resources. While gas flaring was the default solution, increasingly stringent carbon constraints have rendered this solution unattractive. One potential solution entails injecting the otherwise stranded AG into underground geologic systems for temporary storage, but re-producing same when a viable gas market becomes available. Seeking a robust temporary AG solution for a new oil development in the shallow offshore area of the Niger Delta, this paper presents an overview of common AG solutions, examining their relative strengths and weaknesses relative to this case study. Employing analytic and numerical-simulation studies, temporary AG storage in a non-associated gas (NAG) reservoir as well as the later development of both the native NAG and alien (injected) AG resources have been investigated. The main factors that control both the injection and production phases are highlighted. For a given set of abandonment conditions, effects of the gas volume injected prior to the production phase on the ultimate recovery factors of the native and alien gas resources are presented. Additionally, matrix, pseudo-fractured, and fractured injection modes are explored. Based on selected technical and economic indicators, underground storage in a virgin gas reservoir is found to be the most attractive solution to address stranded AG in this example field, and possibly others.