An interview with Erik Dietrichson, Manager - Eastern Region Well Intervention Service, FMC Technologies Perspectives and development of the RLWI business Riserless Light Well Intervention or RLWI – is the term used to describe the method for performing inspection and maintenance of subsea wells from a monohull vessel by sluicing a toolstring suspended in a wireline into the subsea well under full pressure, but without using a high pressure riser. RLWI is a cost efficient method as it can be performed from monohull vessels rather than costly drilling rigs. Wireline operations are used to perform production logging by measuring the locations of liquid in-flow and water content, to install a plug to isolate intervals with high inflow of reservoir water and to re-perforate the well casing by use of explosives to establish a new production interval at a higher level. It is also possible to increase the production rate from a well by removing scale growth that will reduce the well’s flow area. Another routine operation is to install a so-called insert-down-hole-safety-valve, to replace the function of the initially installed safety valve.