The Development History Of Greater Ekofisk

Abstract The Ekofisk Field, discovered in 1969, at a time when exploratory interest in the hostile North Sea was beginning to wane, marked the beginning of a new era in the oil industry. This was an era of remarkable technological advancement, one in which man's ingenuity was pitted against the elements of nature at their worst. With the further discovery of West Ekofisk, Tor and Eldfisk fields in 1970, Edda and Albuskjell fields in 1972 and the decision to develop Cod field discovered in 1968, a comprehensive three phase development plan, one of the largest in petroleum history, was under way - The Development of Greater Ekofisk. Based on nine years of completed development and seven years of Ekofisk production history, this paper reviews the history of development, highlights technological advancements and discusses the problems incurred at Greater Ekofisk. Although certain revisions in design and slippages in schedule have occurred, the original concepts remain valid after nine years. INTRODUCTION Prior to 1959 the North Sea area had attracted little worldwide exploration attention. Although offshore areas were beginning to be widely considered for exploration, none of the onshore oil fields discovered in the previous 40 years around the North Sea would have been commercial if located offshore. However, with the discovery of the giant Groningen gas field in the Netherlands in 1959, exploratory interest in the North Sea began to build. Although the Geneva Convention of 1958 had laid out the basic rules for dividing continental shelf areas. the ratification of 22 nations was needed before the convention became effective. This was not accomplished until 1964 and even then there were disputes between West Germany, Denmark and the Netherlands that were not settled until 1970. In the meantime companies were busy shooting seismic lines and trading data. In this way many companies were ready for selecting promising acreage when made available. West Germany was the first to grant petroleum rights followed by the United Kingdom in 1964. Interest at that time was concentrated in the southern region as water depths were less and the weather less hostile. Drilling in the U.K. began in December that year and discoveries followed quickly; West Sole gas field in 1965. Leman in early 1966, Indefatigable in mid 1966, Hewett in late 1966 and Viking in 1968. Most of this production was from the Rotliegendes formation of Permian age. Phillips Petroleum Company's seismic work, however, indicated a thick Tertiary basin along the median line between Norway and the United Kingdom. This basin of younger age was of much interest since historically much of the world's production was from basins of this nature. The Phillips Norway Group, consisting of Phillips Petroleum Company Norway (Operator), Norske Fina A/s and Norske AGIP A/s, therefore, applied for and was subsequently awarded Norwegian production licenses 016, 017 and 018 in 1965. These licenses covered blocks 7/8, 8/1, 16/11 and 17/12; 818, 8/10 and 8/11; and 1/5, 2/4, 2/7 and 7/11 respectively. In 1967 the A/S Petronord Group acquired 20% interest in the Phillips Norway Group resulting in the present international composition:Phillips Petroleum Company Norway (USA) 36.960%American Petrofina Exploration Company Norway (USA) 30.000%Norske AGIP A/S (Italy) 13.040%A/S Petronord GroupElf Aquitaine Norge A/S (France) 8.094%Norsk Hydro a.s. (Norway) 6.700%Total Marine Norsk A/S (France) 4.047%Eurafrep Norge A/S (France) 0.456%Coparex Norge A/S (France) 0.399%Cofranord A/S (France) 0.304%