Operation Integrity Evaluations for Deepwater Drilling Riser System

Abstract

This paper highlights concerns and operating issues for deepwater drilling risers operated from dynamically positioned or moored rigs, and discusses proper approaches and criteria to evaluate and ensure the operational integrity of drilling riser systems. As drilling water depths go deeper, more operation issues need to be considered. Major operating concerns of deepwater riser systems include: • collapse pressure rating, • handling and lift capacity, • deployment and retrieval, • planned or emergency riser disconnect, • connected operations, • drift-off or drive-off, • hangoff during storms, • fatigue due to vortex-induced-vibration or wave loads. In deepwater drilling, longer and heavier riser equipment, rig motions, weight mass ratio, hydrostatic pressure, mud flow, stiffness, drag, wave, and current all play important roles on riser system integrity, from well head to rig equipment. This paper provides general guidelines to evaluate the drilling riser system of various rigs under normal and extreme operational conditions. Issues for different major operations will be introduced, evaluation methods and associated criteria will be discussed, typical findings and remedial solutions will be presented.