Riser Collapse—A Unique Problem in Deep-Water Drilling

Abstract While drilling an exploratory well in 1750 feet of water, a large kick emptied the marine riser. The two lowest joints collapsed due to the external pressure. A diverter failure also occurred. The equipment damage caused by this incident is described, and collapse calculations for the riser are presented. It is concluded that, if a kick is taken in deepwater after the subsea blowout preventers (BOPs) have been run, the subsea BOPs should be closed instead of activating the diverter, even if only shallow conductor casing is set. Diverter systems remain a must for shallow water operations, but their strength should be reevaluated and perhaps upgraded.