Judy Maksoud
International Editor

LISBON, Portugal -- Oil development in the ultra deepwater Gulf of Mexico represents a great challenge to riser designers. Dr. Elizabeth Frauches Netto Siqueira of Petrobras told participants at the International Offshore and Polar Engineering Conference on July 3 that high wellhead pressures associated with extreme environmental loads make the steel catenary riser (SCR) one of the few alternatives that allow oil and gas production in the ultra deepwater GoM.

The study Siqueira summarized included hurricanes and loop current cases in 2,500 m (8,202 ft) water depth in the GoM and took into account the high pressures normally encountered in the area.

Although this evaluation of maximum stresses is a preliminary one, the results of the analysis demonstrate the feasibility of SCRs, taking into account the need for more resistant and thicker steel tubes and titanium stress joints, Siqueira said. The high wellhead pressure was fundamental in determining the thickness as well as the type of material adopted for the SCR said. The riser was dimensioned with a large thickness, principally to support the internal pressure, but flexional stresses contributed most to the maximum tension in the dynamic analysis in extreme and accidental cases, she said.

Siqueira believes the analysis presented is valid because it evaluated what she referred to as, "the worst conditions possible."

7/3/2007