Samenvatting

OOS Energy Rig Management Services B.V is specialized in reactivating stranded assets. OOS Energy is mainly involved in oil and gas extraction. As rig manager OOS Energy is the connecting link between rig owner and Oil Company. The Semi-Submersible Drilling Rig Frida 1 is one of the rigs currently managed by OOS Energy. At the moment the Frida 1 is operational in the Gulf of Mexico. When she was built in 2011, she was equipped with a cooling system which is fully cooled by outboard water. Now that the Frida 1 is operational at the Gulf of Mexico, she struggles with the disadvantages of such an open-loop system.

In the past a project had started to convert her open-loop system to a closed-loop system. This project was in an advanced stage, plans had been approved by the classification society and purchases such as heat exchangers and pumps were made. Unfortunately execution of this project never took place. The effects from the flaws of the old system are, a lower safety and redundancy and a higher downtime and workload. Many pipelines are replaced due to corrosion or clogging up. Dozens of filters need cleaning weekly to keep the system operational. Currently the rig is 10 years old and is built with a life span of 15 years. This means that the rig will reach the end of its life time in 5 years, OOS Energy would like to extend her life span by undertaking these kind of projects.

The accompanying question is:
How can the current plan to fit the SSDR Frida 1 with a closed-loop cooling water system be implemented?

The purpose of this research is to increase safety and redundancy and to decrease downtime and workload. For this research desk research and quantitative research have been conducted. It has emerged that multiple mistakes are made by the previous intent of conversion. This has led to insufficient capacity of the plate heat exchangers and an incorrect design.

For the Four columns system the calculations show that an additional 60 plates per heat exchanger will provide enough capacity to operate with a sea water temperature of 32°C. The carrying bars and tightening bolts need replacement because they cannot house the additional 60 plates. For the mid ship system it is impossible to solve this problem by adding plates, therefore a different solution should be investigated. This answer could lay in the operation of the drilling braking resistors.

New designs are made to improve the operation and maintenance of the systems. With the new design the probability of cavitation on the impellers of the pumps is reduced to a minimum. Because of costs, maintenance, corrosion resistance and weight, Glass Reinforced Epoxy is the recommended material to use for piping.

The results show that the minimal investment costs for the conversion of the Four Columns systems are € 345.581. It is recommended to install new gaskets which costs are € 19.030. For the Mid Ship system the minimal investment costs are €123.856. Although not necessary it is recommended to install new gaskets and an additional 28 plates per heat exchanger. These costs are € 23.914 and €41.559.