Emergency release analysis of the riser on semi-submersible drilling rig

Abstract:

In deep water oil and gas exploration and development， the operation environment is complex and changeful. In order to avoid the damage of typhoon and other bad weather to offshore drilling， the emergency release of the blowout preventer and the riser has become the key to avoid offshore drilling accidents. In order to explore the recoil law of the riser in emergency release， the causes and recoil process of emergency release of the riser were analyzed. The axial mechanical analysis model was established for the riser system under emergency release condition by using OrcaFlex method. Taking a 1520m deep water well in the South China Sea as an example， the effects of tensioning force， wave movement， drilling fluid density and platform drift on riser recoil were studied. The results showed that the larger the top tensioning force was， the larger the recoil displacement of the riser and the change of the stroke of the expansion joint were. With the increase of wave height， the recoil response of the riser tended to strengthen. The wave direction had no effect on riser recoil response. Different drilling fluid densities in the pipe had obvious influence on riser recoil. With the increase of platform drift distance， the recoil response of the riser became more intense. The research results have certain guiding significance for the safety of the riser in recoiling.

Key words:deep water drilling;riser;emergency release;recoil;OrcaFlex