Subsea flexible flowline installation issues and solutions

First, flowline initiation with PLET was discussed. Two options were compared, and whipline option was recommended. Second, flowline laydown with PLET was presented. Buoyancy module option was used since the layback distance is a control parameter to ensure a safe landing. Third, issues associated with in-line SLEDs were investigated. Detail landing analysis was needed to ensure the bending restrictor would not experience overbending. Fourth, buoyancy module wet parking and underwater transfer were checked, it was found that the buoyancy modules are fairly stable during wet parking stage, however, special action is required during transfer to mitigate the snatching loads. Fifth, flexible twisting phenomenon during transpooling was analyzed. Flexible twisting occurs commonly during handling and transpooling, and mainly due to its residual torque during manufacturing and transpooling arrangement. Recommendations were provided to mitigate the twisting angle. Last, the topic covers flexible curve laying. Flexible small radius curve laying under strong current was proven to be very challenging. Feasible options of improving the chance of success were presented.