Rigless Tubing Retrieval for Plug and Abandonment and Slot Recovery Operations on the Norwegian Continental Shelf

Abstract

The conventional way of performing permanent P&A operations on the NCS have been with the use of a drilling rig. It is believed that this is not the optimal unit for the purpose, as they are costly to run with day rates up to 6,5 MNOK and being massive and therefore slow to relocate. The rigs are in addition not primarily made for performing P&A operations and are therefore not optimized with regards to layout and machinery. The solution that the industry has been moving towards the past years have been the vessel, which have significantly lower day rates. A Riserless Light Well Intervention (RLWI) vessel may have day rates at around 2 MNOK while it also has lower traveling time between the wells. If equal efficiency of the operations may be obtained with the use of vessels, it is observed that there are substantial amounts of money to be saved. There are limitations and challenges related to being able to fully complete a permanent P&A operation without the use of a rig, but it is believed that progress is being made as the industry is working towards the same goal. This thesis will elaborate on how Equinor have approached rigless P&A in their company. It covers one of Equinor’s most recent projects within rigless P&A, which is to be able to pull production tubing in open sea with the use of an RLWI vessel. The thesis will cover the technical requirements related to the project and the proposed solutions. The operations are expected to be executed on candidate wells during 2021.