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An industry first for flexible riser life extension - FlexIQ completes project for Shell

27th April 2018

FlexIQ, a partnership between INTECSEA, an engineering consultancy, and Innospection, an inspection provider, has achieved an oil and gas industry first.

The collaborative effort provides life extension evaluation for flexible risers, based on a fully simulation-based irregular wave fatigue assessment advised by inspection data, establishing a step change in technology. This approach has been successfully used for Shell Nigeria’s two Bonga flexible risers.

Naren Ramaiah, Head of Pipeline & Integrity, Shell Nigeria said: “Our offloading system is configured with flexible pipelines, which are designed for onerous loadings and stresses. Assessing and assuring its integrity regularly is very important for our safe operations.”

This technique combines two proprietary technologies: the MEC-FIT™ inspection tool and the FLEXAS™ numerical solver, which allow high-resolution stochastic fatigue life to be captured based on realistic conditions.

• MEC-FIT enables inspection of the tensile armour wire layers through the outer sheath of the flexible riser. This technology can be deployed on long riser sections and is uniquely able to detect defects within multiple layers regardless of the annulus condition.

• FLEXAS offers the only solution framework available in the industry that computes irregular wave wire stresses using dynamic simulation of high-fidelity finite element models. This eliminates approximations and uncertainties associated with non-simulation based approaches. This solution includes detailed damage modelling from inspection data to produce the industry’s most accuratewire stress computation.

Shell Nigeria commissioned the FlexIQ team via Innospection’s partner FADFAE Engineering Services, to determine the current condition of its flexible risers and provide recommendations for the future safe operation of the Bonga Oil Offloading Risers located offshore Nigeria. Bonga has been producing since 2005, and the risers are currently 15 years into their original 20-year design life.

FlexIQ has been used to re-evaluate the design life and determine the suitability for life extension of the risers. The MEC-FIT inspections detected no wire corrosion damage, leading to the FLEXAS irregular wave simulations predicting low rates of fatigue accumulation. Embedding the inspection and analysis results into a risk based framework enabled operational risk to be quantified. The analysis predicted safe and reliable operation of the assets well beyond the original design life.

Dr. Kirsten Oliver, Asset Management Lead for INTECSEA stated: “We are delighted to have used innovative technology to give Shell Nigeria the confidence and understanding to continue operating its risers.”