Flexible Pipe continues to Pioneer Ultra Deep Water Flowline Riser System Solutions

Published: October 2000 | 3rd International Conference on Composite Materials for Offshore Operations | October 31 – November 2, 2000 | Houston, Texas, USA

Abstract

Offshore Oil & Gas Exploration and Production in deep water continues to provide the industry with significant technical challenges.  Remarkable advances have been made in the development of unbonded flexible pipe structures to meet these challenges. Less than three decades ago saw the first installation of flexible pipe in offshore oil & gas production.  By 1990, flexible pipe was qualified and being installed in dynamic service up to 1000 m water depth.  This paper discusses the innovative design techniques adapted, combined with the use of advanced materials, to expand the water depth/diameter envelope for flexible pipe. An insight into the research and development program which led to the first qualification, installation and operation of unbonded flexible pipe for up to 2000 m water depth is presented.  With the advantages of rapid deployment using low cost installation methods, high reliability and structural redundancy, and increased flexibility in vessel and mooring system design, flexible pipe continues to be a preferred solution for deepwater flowlines and risers.   The methodologies developed to address the deepwater challenges that are addressed in this paper include:

• The requirement for increased hydrostatic collapse resistance, and the ability to predict the lower bound collapse pressure so that lower safety factors can be employed, thus reducing weight and cost.
• Increased axial compression resistance to withstand the reverse end cap load due to high external pressure.
• Reduced weight to reduce top tension and floating structure buoyancy requirements. Both composite material substitution for steel structural reinforcement, and riser section design optimization techniques are considered.

Options for flow assurance solutions using flexible pipe are also presented, including both active heating systems and high thermal resistance products.  The technical challenges to employing flexible pipe in water depths up to 3000 m will also be addressed.

Authors:

Kalman, K., Chen, B., Loper, C., Tuohy, J.