We consider the assessment of the availability of oil and gas processing facilities operating under Arctic conditions. The novelty of the work lies in modelling the time-dependent effects of environmental conditions on the components failure and repair rates. This is done by introducing weather-dependent multiplicative factors, which can be estimated by expert judgements given the scarce data available from Arctic offshore operations. System availability is assessed considering the equivalent age of the components to account for the impacts of harsh operating conditions on component life history and maintenance duration. The application of the model by direct Monte Carlo simulation is illustrated on an oil processing train operating in Arctic offshore. A scheduled preventive maintenance task is considered to cope with the potential reductions in system availability under harsh operating conditions. Keywords: Dynamic weather conditions, failure rate, repair rate, equivalent age, preventive maintenance, availability, Monte Carlo simulation, oil and gas, Arctic offshore. , ′ ); = 1, … , ; 0 ′ = 0, partitioning the time horizon, during which the weather conditions remain unchanged at an intensity level of . In this study, the time interval length is taken to be equal to a day.
Acronyms
ALMReliability of a component operating under static weather conditions at WIL State of the system at WIL , = 0, … , ; = 1 and = 0 refer to the functioning and faulty states, respectively. Waiting downtime before commencing CM tasks in the base area, which includes the time required to shut down the unit, issue the work orders, wait for the spare parts, and start up the unit after repair.Weather element referring to either minimum daily air temperature or maximum daily wind speed, i.e., ∈ { , ′ } ( ) Maximum wind speed during in km/hr ′ ( ) Box-Cox transformed wind speed at the th day The factor by which the weather-dependent factor , changes due to modifications to plant design The factor by which the weather-dependent factor , changes due to modifications to the comfort of maintenance crew, or modifications to the plant design resulting in changes in component active repair time 0 Weibull shape parameter, estimated using the life data collected in the base area (i.e., normal weather conditions), partitioning the time horizon; during each time interval the weather conditions are assumed constant Weather-dependent multiplicative factor corresponding to the WIL , = 0, … , with 0 = 1, which accounts for the reductions in TTFs. Weather-dependent multiplicative factor corresponding to the WIL = , = 0, … , at the th time interval = 1, … , which accounts for the reductions in TTFs Weather-dependent multiplicative factor corresponding to the WIL , = 0, … , at the th time interval = 1, … , which accounts for the rises in TTRs Weather-dependent multiplicative factor corresponding to the WIL = , = 0, … , at the th time interval = 1, … , which accounts for the rises in TTRs * Modified weather-dependent multiplicative factor corresponding...