First Diverless Subsea Wireline Well Intervention Performed in Offshore Vietnam offers Low-Cost Solution for Light Well Workovers: Case Histories and Future Trends

摘要

Subsea completions have been on the rise in recent years duernto the economics, extreme environments, the use ofrninfrastructures (subsea tiebacks), and migration to waterrndepths in excess of 1300-feet. In this paper, subsea slicklinernoperations are performed on three cluster wells situatedrnbeneath the operator’s semi-submersible floating productionrnunit in Vietnam’s offshore Dai Hung field. The services werernneeded for reservoir management, including installation andrnretrieval of memory gauges, performance of logging surveys,rnand to manipulate sliding sleeves that had been installed withrnthe ultimate purpose of optimizing hydrocarbon recovery. Arnsubsea wireline unit (capable of deploying slickline andrnelectric line) was chosen to provide the services. This unit wasrnselected because of its cost efficiency and capability tornperform a fishing job without impacting platform space andrnweight restrictions on the floating production unit as wouldrnhave been imposed by use of a drilling riser. This paper willrnprovide the case history of these services, which were uniquernin that these were the first diverless subsea slickline jobsrnperformed solely with remote-operated vehicle (ROV) supportrnfor manipulation or assistance. Slickline provided an effectivernsolution for the operator’s service requirement within thernspecified criteria. Because of the versatility of newlyrndeveloped advanced systems, slickline equipment was able tornmeet the restrictions of weight and size on platforms tornprovide a more efficient alternative for services thatrntraditionally require rig mobilization.rnAs a result of the success of this operation, the operator isrnplanning other subsea slickline services that will be performedrnwithout a drilling or jack-up rig.rnWith the present economic climate of the oil-and-gasrnindustry, the significant costs normally associated with heavyrnworkover and drilling facilities have strengthened the need tornfind other ways to enhance cost efficiency in subsea workoverrnscenarios. To support this trend, innovative methods that havernexpanded the scope of operations that can be performed onrnsubsea wells without a drilling rig have now been introduced.rnAs an example, plug and abandonment operations can bernperformed with subsea wireline intervention units and otherrncoiled tubing and wireline intervention techniques rather thanrnwith a tensioned riser from an anchored drilling vessel or arnjack-up rig. With the new methods, the deployment system forrnwireline and coiled tubing does not require special systemrnmodification—any standard wireline or coiled tubing unit canrnbe used. These techniques will be discussed more fully in thernpaper.