Retrieving an unreliable blowout preventer (BOP) is a necessary but expensive operation, costing upwards of US$1-2 million dollars. This cost can easily escalate in developing ultra deepwater regions such as Brazil, West Africa and Gulf of Mexico. 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 research and development center in Rio de Janeiro, the BOP-RDT tool provides a comprehensive decision support system, using both quantitative and qualitative methods, to assist the decision-making process by reducing its 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 research and development 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.”
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 structure-function of all BOP critical safety functions included in the system. 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 more 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.
This complex information, obtained by numerical computational algorithms, is transformed into a very intuitive graphic visualization user interface. As a result, the BOP-RDT users will be presented with color-coded indicators of the reliability degradation of each BOP safety function due to any detected component or subsystem failure in the BOP.
“Like any operator, in any region in the world, cost-efficiencies can be gained from making the right decision, quickly and effectively. This new tool, which was developed at our research and development center in Brazil, provides technical, financial and reputational benefits to operators,” said Alexandre Imperial, regional manager, South America, DNV GL - Oil and Gas. “It is very user-friendly, fully customizable to each BOP, and does not require risk or reliability experience to use it. As it improves consistency of BOP retrieval decisions, while providing a track record of failed and restored components, it gives stakeholders increased transparency on drilling activity. Its main purpose is to ultimately reduce BOP downtime while maintaining acceptable safety margins.”