Permanent Plug and Abandon (PP&A) operations of the existing production and exploration wells continue to have a higher focus in drilling and well operations for Oil & Gas Companies. It is expected that they will play an important role in the future, and their further optimization and simplification is even more important. This paper describes a successful approach and execution of a challenging Permanent Plug and Abandon operation of a subsea well in the Norwegian Sea by Statoil.
A subsea well at over 350 m water depth was being drilled, when a casing running tool was stuck at the subsea wellhead when running an intermediate casing string. This led to a temporary well abandonment, before permanent P&A operations could be resumed at a later stage. Several concepts and contingency scenarios were evaluated and risk assessed in the planning phase, which required implementation of nonstandard and innovative P&A solutions and equipment. They were developed in the planning phase and reviewed with planning and execution teams, and tested before the operational start-up. Main P&A operational goals were established in the planning phase, and successfully implemented during the operations: 1) well control — confirm there is no gas and no well control risk in the well before resuming P&A operations, 2) gain access to the well by retrieving stuck tool from subsea wellhead, and 3) establish permanent P&A barriers in the well.
Both planning and execution of this operation is described in this paper, which includes main planned operations, and also a strategical approach with several contingency scenarios prepared in order to be able to P&A this well permanently.