Development of Novel Integrity Assurance Approach for Technology Qualification of New Subsea Technologies by Deepstar®

Abstract

Deployment of new technologies could give rise to unknown modes of failures resulting in a lack of success for the technology. With no or limited failure data available in the field, the integrity of the equipment is ensured through testing and qualification. Individual companies have methodologies but they vary from company to company and the level of testing before a technology is considered qualified from the point of integrity also varies. This results in repeated qualification of the same technology, impacting project time-lines and costs. Further, the inference that the system has the required integrity remains qualitative and the testing carried out can be sufficient or excessive, with consequence on costs. A Deepstar® study has been carried out to develop a methodology where integrity of the various components of the new technology could be quantified, even in the absence of failure data from the field. The study recognized the importance of having a common understanding and definition of key principles used in technology qualification and a common view on integrity assurance acceptance criteria among the oil and gas industry. Integrity Assurance of a technology, defined here as the assurance to meet a specified set of integrity requirements at every point during its design life, is the novel methodology proposed and outcome of the Deepstar® study. The Integrity Assurance index accounts for both integrity and reliability of a system and it is ultimately expressed as a function of the mean life, the confidence in the probability of failure estimated and the expected life of a technology operating in a subsea environment. A particularly innovative approach is the introduction of failure categories using an association to Weibull distributions representative of a series of subsea equipments, based on the population statistics from failure distributions of similar equipment in O&G as well as in other adjacent industries. The methodology developed provides a link between a qualitative assessment and a quantitative analysis that can be used to evaluate the integrity qualification of new technologies used in complex subsea systems. The application of methodology will be illustrated here. Future work can use the Integrity Assurance index developed from component levels to estimate the overall system integrity. The achieved system integrity can then be compared to acceptance criteria to have a common definition for the qualification of the new technology from the point of view of integrity and reliability. Upon industry acceptance, this conceptual method could provide the Operators with the additional level of confidence in the integrity of a new system and a measure of the degree of technical risks involved in operations.