SYSTEM FOR CONVEYING FLUID FROM AN OFFSHORE WELL

摘要

The riser system of the present invention includes an external production riser for floating structures with interfaces to the dry and subsea wellheads, internal tieback riser with a special lower overshot/slipping connector for elevated temperatures. The seals can be metallic and/or non-metallic dynamic seals. Special centralizing pipe connectors and a special subsea wellhead tubing hanger are also included. This riser system avoids the penalty of pipe within pipe differential thermal growth and the resulting unwanted effects on the floating structure. This is accomplished by allowing an overshot sealing slipping connector to swallow an expanding polished rod as thermal conditions cause pipe elongation axially. When elevated temperatures fall to ambient the opposite occurs as the pipe shrinks axially. Alternatively, a system is possible where a two pipe drilling riser is needed. The internal pipe in this case would be an inner riser rather than a tubing string.