Probabilistic Operability Analysis of Drilling Riser by Metamodel Methodology

This work proposes an efficient methodology for drilling operability prediction considering environmental loading uncertainties. Drilling systems are an important part of oil and gas exploration particularly in deep waters. In drilling systems, drilling riser play a vital functional role. The drilling riser have to be designed to maximize their operability capacity and cost-effectiveness. However, traditional method for operability envelope estimation is difficult to account for randomness, correlation and uncertainties associated with various environmental loads. Reliability method accounts for uncertainties, but Monte Carlo Simulations (MCS) requires high computational time, e.g. 107 × 3-hour simulations required for 10-5 probability. Although use of reliability based approach in riser design is proposed in various codes and research articles, few work has been conducted for probabilistic operability estimation till date. An efficient reliability method based on metamodel technique is proposed for probabilistic operability envelope analysis. The connected mode drilling operability based on reliability method show that tension operability envelope can be expanded based on DNV target probability.