Ninian Third Party Project: A Unique North Sea Challenge

ABSTRACT The Ninian Field, operated by Chevron on behalf of the Ninian Field Group, is a mature North Sea producer. Rationalisation of the topside facilities and declining production rates had left spare equipment and capacity in the Platform production systems. This spare capacity coupled with Ninian's strategic location in the Northern North Sea made it an ideal candidate for tie-in of subsea fields. Staffa, Lyell and Strathspey, operated by Lasmo, Conoco and Texaco respectively, are three such third party subsea developments using Ninian topside facilities. The Ninian Third Party Project is unique since it is the first offshore development where three third party operated subsea fields are processed by another operator and developed within the same timescale. In addition, major topside modifications were performed while Ninian continued to operate. Through sharing the lessons learned by Chevron as operator and manager of the Third Party Project, others will benefit in improved efficiency, planning and organisation for similar future endeavors. The impacts of managing a major project (over 3 million offshore construction manhours) with an existing operations infrastructure, interfaces with Third Party Entrants, safety, productivity and efficiency results are among the issues which will be addressed. INTRODUCTION The Ninian Field is located some 110 miles North East of the Shetland Islands within Blocks 3/3 and 3/8 in the area commonly known as the East Shetland Basin. The Ninian Field maintains a strategic position in the Basin. The field was discovered in February 1974 and began production in December 1978. With an estimated 3 billion barrels of oil in place, the field is expected to recover 1.2 billion barrels of oil producing well into the next century. The field was developed using three platforms, the giant concrete Ninian Central and the two conventional steel structures of Southern and Northern. Oil export from Ninian is via a 36" pipeline to the largest terminal in Europe - Sullom Voe located 110 miles away on the main island of the Shetlands. Oil from Ninian Southern is pumped up and over Central through a manifold to the 36" export line. Ninian Central also acts as a hub gathering production from Unocal's Heather Field, BP's Magnus Field and Total's Alwyn North Field. Since their initial construction, all three platforms have received regular updates to their production systems. On Ninian Southern and Central Platforms the original two train, three vessel production separator systems have been optimised to single train, two vessel operation, leaving redundant production vessels in place. Also on Ninian Southern Platform in response to Ninian's declining production and reduction in associated fuel gas availability the LPG recovery plant was decommissioned. For these, and other reasons, Ninian Southern and Central Platforms were best suited for host satellite developments.