Trade-off Between Sample Size and Test Time: Lessons Learned in Optimizing Reliability Demonstration Test Plan

Intelligent completion systems are permanently installed downhole in severe operating conditions and are designed to achieve high operational reliability in high temperature and pressure applications. An accelerated reliability demonstration test (ARDT) is typically required to demonstrate if the system has met its reliability target. ARDTs are typically setup as a success test and all test specimens are expected to survive the test time. To satisfy the constraints on testing expense and product development time, a key step in designing an ARDT plan is to perform a trade-off between sample size and test time to meet the reliability target at the desired confidence level. Generally, a large sample size results in a shorter test time and vice versa.