Scale operations from monohull vessel

Abstract

The advances within the oil and gas industry have provided opportunities to expand into deeper and more remote areas. One of the most important technological advances comes from the development of subsea equipment. The increase in subsea developments also resulted in advances of other technology. Inspection, maintenance and repair (IMR) operations is an important element in keeping subsea developments cost-effective. Scale is an unwanted chemical reaction that can occur during hydrocarbon production. It is one of the most common problem areas in the oil and gas industry especially for subsea developments. Scale management from monohull vessels is essential for many subsea developments. Scale operations are performed from monohull vessels with advanced scale treatment equipment. An important piece of the equipment is the Black Eagle hose system. During scale operations the Black Eagle hose is connected subsea and used to pump chemicals into the required well. The setup of the Black Eagle hose system can lead to high forces on the hose during launch and recovery. This setup and the structural strength of the hose set the limiting factor for scale operations to 4 m Hs. This thesis investigates the scale treatment system on Statoil IMR vessels. Focus has been on locating challenges regarding the Black Eagle hose system used on Edda Fauna. After assessments of the found challenges were performed, work was initiated to suggest improved solutions to the Black Eagle hose system. Calculations have been made to check the feasibility and the potential of the proposed improvements. The concluding part of this thesis is based the results from the calculations and on experiences from, studying scale, traveling offshore and discussions with offshore and Statoil personnel. The proposed improvement solutions to the Black Eagle hose system can lead to several of the problem areas being improved. The conclusive remarks indicate that the proposed ideas are feasible and will lead to increased productivity for future operations. The results and conclusions made in this thesis should be used as a basis for further discussions regarding improvements to the Black Eagle hose system and the IMR vessels.