Abstract

In seven years, the North Sea has passed from a little-known basin to an established major gas and oil province. Ekofisk Field, the first significant oil discovery, occurs on an elongated dome formed by diapiric movement of the deeper Permian salt. The Danian (basal Tertiary) limestone reservoir has been penetrated by four wells on the structure. Early studies show the limestone is a typical biomicrite consisting of coccoliths and foraminifera, probably deposited in a deep quiet-water environment. Formation tests in all wells indicate reservoir continuity and high production rates of low-sulfur 35° API oil. Commercial production will begin early next year by unusual use of conventional facilities.