Retrieving an unreliable blowout preventer (BOP) is a necessary but expensive operation, costing upwards of one or two million dollars and easily the double in developing ultra-deepwater regions.
It is also the main cause of downtime during drilling activity. DNV GL is introducing the BOP▪RDT, a real-time, risk-informed BOP retrieval decision support tool to enable operators to determine when to retrieve the BOP for repair after a detected component failure.
Developed at DNV GL’s R&D Center in Rio de Janeiro, the BOP▪RDT tool provides the most comprehensive decision support system, using both quantitative and qualitative methods. It will assist the decision-making process by substantially reducing the degree of subjectivity.
“Any failure in a BOP during drilling is undoubtedly a cause for concern,” said Luiz Fernando Oliveira, tool developer, and manager at DNV GL’s R&D Center in Rio de Janeiro, Brazil.
“However, not all component failures are equally significant. Though some may lead to the total loss of a BOP critical safety function, others may have no impact on its continued safe use. Therefore, it is important to determine as concisely as possible when to leave it alone or retrieve it for immediate repair. This tool reduces uncertainty and improves decision-making on individual cases, ultimately saving on the costly implications of downtime during drilling,” Luiz added.
Using deterministic criteria, the BOP▪RDT applies a detailed qualitative method to help guide decision-making. This is entirely based on the losses of redundancy resulting from the impact of detected failures on the reliability of all BOP critical safety functions included in the tool.
But much more than that, the BOP▪RDT also offers a fully quantitative risk-informed decision support system.
This is based on an advanced time-dependent reliability analysis of each safety function before (normal condition) and after one or several detected component or subsystem failures.
Alternatively, a combination of qualitative and quantitative methods and criteria can be used to guide the BOP retrieval decision and allow for its use in different regions of the world.