| dc.description.abstract | The oil and gas industry has been motivated towards pushing the research and development of subsea systems. A core element of this development is to design these systems with high reliability to insure productivity and payback. However, the scarcity of data, harsh subsea environment, and complexity of subsea systems made the task more challenging and complicated. Hence, a typical practice for novel systems is going through a Technology Qualification Programs.
This thesis aims to assess the reliability of a Wax Control System, by predicting the failure rates of the individual components. The results shall be used as an input in a Technology qualification Program. The novel subsea system was developed by Subsea 7, the invention of it was based on the Cold Flow Assurance methodology to overcome the challenge of the deposition of Wax on the inner walls of the pipelines by continuously scraping the wax with a cleaning pig. The objective of this thesis is to have realistic reliability distributions (i.e. failure rates) for these components.
However, there has been no approved approach or method to follow when it comes to predicting reliability of mechanical components. Moreover, the zero-failures of the components make the task more challenging. Therefore, the initial method was to follow the estimation procedure for non-failure components, mentioned in the most dependable data source in oil and gas, OREDA handbook. Nonetheless, the procedure has its own flaws and limitations. Thus, examining a prediction approach to adopt was essential. It was concluded that having an approach that uses failure modes, failure mechanisms, reliability influencing factors, and the expert’s judgment would be more fruitful. Consequently, a soft adoption of Rahimi & Rausand’s approach was made, in which adjusting some steps was necessary. Although the adopted approach is primarily using OREDA’s data, the results were different. After implementing the approach, it was concluded that reliability of the components was higher than what was claimed by Subsea 7. | |