Complex plug and abandonments are required when it is not possible to permanently seal a wellbore utilizing conventional methods. This paper will provide an overview of advanced survey management techniques and their application to complex wellbore abandonment operations. The overview will include the utilization of technologies including active magnetic ranging, gyroscopic and magnetic surveys, and advanced survey correction algorithms. The economic benefits due to the successful outcomes will be shown as well as the mitigation of potential environmental hazards to groundwater aquifers.
The described methods have been proven in real-world scenarios, where complex technical challenges necessitate the requirement of a complex abandonment. Two case studies will be presented; one operation where the target well suffered from a restriction in the casing that prevented access to the reservoir, and another where a wellbore was found during civil construction activities in an unexpected position and created a high-risk challenge due to the potential for reservoir gases and liquids leaking uncontrolled into the construction zone.
The application of these techniques in abandoning complex wellbores that are unable to be plugged by conventional means provides the industry with solutions to the technically challenging problem of wellbore abandonments when physical access to the wellbore is not possible. These techniques provide economical and low-risk solutions to operators in both onshore and offshore decommissioning activities.