Ekofisk--First of Western European Giant Oil Fields: ABSTRACT

Abstract

The discovery in December 1969 of Ekofisk field in the Norwegian sector of the North Sea was a major turning point in the exploration for petroleum in Western Europe and rejuvenated the search for oil in the North Sea. Current production in the North Sea is 1,466,000 BOPD, and the total proved reserves are estimated at 18 billion bbl, with estimates of ultimate reserves ranging as high as 40 billion bbl. Records reveal that Phillips had been operator of seven wells in Norway (one of which was at that time considered to be a noncommercial gas-condensate discovery) before Ekofisk was found with its eighth well. The company had drilled 25 exploratory wells in the North Sea, one of which had found a major gas deposit, but none had found oil. A total of 33 wells had been drilled in Norway without finding commercial oil before Ekofisk was discovered by the 34th well. The Ekofisk structure was mapped by Phillips using its End_Page 701------------------------------ common-reflection-point seismic system. On a reflector near the Danian the structure exhibited closure of about 600 ft (1,830 m) over an of 13,500 acres (5,463 ha.). What appeared to be a graben or downfaulted block covering part of the crest of the structure was referred to as the area on the original seismic maps. Seismic time sections showed two crests, with reflectors turning sharply downward into this central graben. A discovery and three evaluation wells, testing up to 3,850 BOPD, were drilled outside the central graben. Later, when permanent platforms were installed in the Ekofisk field, a well was drilled in the center of the and found 1,033 ft (3,149 m) of pay. Actually, there was no graben or collapsed area; the seismic anomaly which gave rise to this expression proved to be a velocity phenomenon due to the tremendous thickness of hydrocarbon-saturated, porous limestone. Cumulative production from Ekofisk was 420,629,516 bbl of oil and 337 Bcf of gas sold through October 1978. Six satellite fields are being developed, four of which are on production as part of the Greater Ekofisk complex. Some of the Ekofisk wells have produced at rates greater than 20,000 BOPD. Estimates of proved reserves of the Greater Ekofisk complex indicate that it is a multi-billion barrel field. End_of_Article - Last_Page 702------------