Final field permanent plug and abandonment - methodology development, time and cost estimation, risk evaluation

Abstract

Quote from Douglas C. Nester, COO Prime Offshore LLC: “P&A obligation is like death; you can try to delay it for as long as possible, but sooner or later it will occur.”[1] Many wells on the NCS (Norwegian Continental Shelf) will need to be permanently plugged and abandoned during the next 50 years. In order to do proper planning for these jobs, a good methodology, cost estimation and risk evaluation procedure is needed. Statoil recognizes this need, and from the help of data provided by Statoil and its participation with other major companies worldwide, this thesis has been developed. This thesis will mainly concern offshore PP&A (Permanent Plug and Abandon) operations on the NCS. The main focus of this thesis is on technological solutions which may lead to better plugging results and less expensive operations. The thesis also covers an overview of rules and regulations, cost and time estimation per Statoil ASA, Conoco Phillips and Oil and Gas UK guidelines. An overview of challenges and risks concerning PP&A operations is also provided. The work on this thesis has revealed that there are potential for reducing time and cost related to PP&A operations. Some of the elements which may impact PP&A operations in a beneficial manner are: - New cutting technology - Alternative to section milling - Alternative plugging materials - PP&A vessel modifications