Through Barrier Diagnostics to Locate Multiple Barrier Failures in Complex Well Failure Scenario and to Enable Successful P&A

Abstract

A 60-year-old well exhibited a leak at the surface and sustained annuli pressure (SAP) in all three annuli - A, B and C. The age of the well coupled with the symptoms suggested a complex multi-barrier failure scenario that needed to be diagnosed quickly and accurately so that the well could be secured safely. The paper shows how the comprehensive set of downhole diagnostics, including metal and cement barriers integrity assessment, aided in planning and execution of well intervention to secure the indicated failures. The well intervention team selected an approach to investigate the barriers status prior the rig came to the location. Surface diagnostics included evaluation of pressure trends, completion design, leak fluid composition and drilling records analysis which guided the selection of downhole survey. The input parameters for downhole through barrier diagnostics were: Downhole through barrier diagnostics targeted the evaluation of leak paths and failures in well barriers and included: This paper explores the concept, planning, execution and achieved results of the downhole diagnostics performed and how the results were implemented by Operator.