This report describes the development of the riser system, which consists of a 17-in. ID, high-strength steel riser with 4-in. ID integral choke and kill lines and an air can buoyancy system. A free-standing bouyant riser feature permits the vessel to be disconnected from the riser in the event of severe storms. The development of riser design criteria is discussed. Vertical vessel and riser motion during installation, retrieval, and storm disconnect dominate the riser's structural design and require a variable buoyancy system. This report recommends that improved computer codes be used to further optimize the design of the riser, particularly in the suspended mode, and the development of critical system components be initiated as early as possible during the preliminary design phase. The program's general design criteria called for a vessel capable of performing drilling and coring operations with riser and well control equipment in 4,000-m (13,200-ft) water depths with a total drillstring length of 10,000 m (33,000 ft). The conceptual baseline riser system described here represents a feasible, cost-effective solution to one of the critical technical issues facing the OMDP. The system utilizes existing, field-proven technology wherever possible. Design Criteria for the OMDP riser system are presented. 2 refs.
