Risers Clashing Induced by the Wake Interference

Abstract

The offshore petroleum industry has great technological challenges as new field discoveries are made in increasing water depths. Risers of systems having little space between its elements, subjected to current reach static deflections that depend on the wakes formed by the each riser. Depending on the relative position, each riser will be submitted to a stronger or weaker effect from each neighbor. This work presents results from experiments with flexible jumpers submitted to current. The clashing between the lines caused by the wake interference is the focus of the work. The work presents results in terms of minimum distance between the jumpers comparing experimental results to a numerical code that applies automatically the Huse’s formula for the drag coefficients. It also discusses the validity of this theory. As expected, during the tests the jumpers presented Vortex Induced Vibration (VIV), VIV under Interference (VIV-UI) and friction after contact. The results can be extrapolated to real cases and shows the possibility of clashing on closely spaced systems, putting in evidence other phenomena related to it.