Operating Experiences from Second Generation Riserless Light Well Intervention (RLWI) in the North Sea

摘要

With the growing number of ageing subsea wells in the North Sea needing some sort of intervention, the demand for efficientsubsea light well intervention service continues to grow. Such service has been in operation in the Norwegian sector for thepast six years and is currently experiencing exponential growth with the addition of several more intervention systemsspurred by continued long term commitments.This paper presents a review of performance gains from second generation riserless light well intervention (RLWI)equipment currently working in the North Sea, focusing on the performance gains in-water umbilical management, safer deckhandling, efficiency from remote in-situ fluid delivery, and hydrate control. Improved well control “barrier” equipment nowaccommodates 1/3 longer length wireline tools, electric-powered control system architecture using ROV-type control cable(umbilical), autonomous grease injection capability, subsea monitored chemical injection and fluid exchange/ flushingcapabilities have reduced fluid wastage and contingency tankage requirements; all introduced from recommendations andlessons learned from first generation RLWI systems