Flexible pipe systems offer operators a robust method of producing oil and gas fields in harsh environments. The design of the flexible pipe is made according to international standards and internal rules to enable them to withstand the required loadings with a sufficient margin of safety. As these flexible pipes are key components of the field architectures, continuously assessing their integrity allows improved management of system risk and operability. The objective of this paper is to detail how Condition and Performance Monitoring (CPM) of the flexible risers enables a dynamic integrity management strategy.
Leveraging existing sensors, specific to the flexible pipe or for the overall production system, the integrity through specific failure modes is monitored. This implementation of CPM for flexibles is based on a set of complementary modules such as respect of design envelope, ageing of polymeric layers, annulus monitoring and fatigue of metallic wires. Actual and measured data - e.g. dynamic, thermal and pressure loading – reduce the uncertainty on these assessments with respect to design. Proper technical knowledge of the flexible pipe behavior allows monitoring of the underlying degradation mechanisms.
The information gathered from sensors is analyzed through specific algorithms for the flexibles linked to the CPM platform, allowing the user to visually see the results of the assessment. These data may also reflect possible human errors. This allows an early assessment of gaps (if any) between calculations performed at design stage & actual condition on the field, once these gaps are analyzed, flexible risers potentially at risk could be identified. To address the identified risk, on a case by case basis, specific inspections can be triggered or mitigating measures taken. By monitoring known failure mechanism, the probability of downtime is consequently reduced. Furthermore, the remaining life calculation on the equipment is more accurate with reduced uncertainties triggering more robust life extension decisions.
This paper demonstrates how an automatized use of the data from sensors allows for dynamic and optimized integrity management. This paper also demonstrates the added values in monitoring integrity of flexible pipes for OPEX (OPerational EXpenditure) optimization and to minimize offshore interventions.