Challenges Faced in Design & Selection of Umbilical for Offshore Facilities

The present trend is to use the umbilical for transmitting electrical power, instrumentation signals and to transport fluids & gas in one assembly over long distance to the Offshore Oil and Gas facilities. The installation of power generation facilities at offshore platforms is not a preferred option due to space constraints and the huge installation and running cost. Hence, the electrical power is transmitted from onshore generation facilities to offshore facilities by composite subsea cables. Similarly for example the cost of installing corrosion inhibitor package at offshore facilities is huge considering the space occupied by the package skid which in turn increases the structural cost. The electricity required to run the corrosion inhibitor pump motor and other auxiliaries will result in higher power demand and subsequently the higher installation and operation cost. Hence, it is economical to transfer the corrosion inhibitor from nearby onshore facilities to offshore facilities by using instrumentation tubes, pipes and hoses. The use of umbilical which houses the composite subsea cable and tubes carrying fluids/gases in one assembly result in substantial cost savings in terms of installation, transportation and laying cost. The housing of submarine composite cable with tubes in one assembly poses many challenges for the design and selection of umbilical. This paper provides comprehensive ideas about design, testing and selection of umbilical, the challenges faced and the way forward to overcome the challenges in selection of umbilical.