TheNorthSea-ANe\v Major Oil Province In a Changing World

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Abstract Current exploration in the North Sea is described and latest estimates of the reserves of oil and gas are given. The field development program is reviewed and forecasts of production presented. The principal economic constraints are identified and examined against the recent position taken by tile UK Government on tax and participation. Events during the past few years have combined to make the oil developments in the North Sea, paticularly interesting. Technically, the deep and hostile water of this latest major new oil province have demanded new solutions for new problems. Economically, the incidence of runaway inflation on high-cost development at a time when massive new taxes have been introduced to take advantage of high oil prices has created unique financial stresses. Politically the impact of the development on industrial countries has bud considerable social and national repercussions within a short period. History SOME 6,000 exploration wells were drilled onshore in Western Europe during the period 1920–59, resulting in a maximum total production of only 250,000 bbls/ day and few important gas discoveries. There was little basis, therefore, for anticipating spectacular hydrocarbon accumulation. In 1959 however, the giant gas field of Slochteren was discovered in the Netherlands, in a geological setting which immediately suggested that similar prospects might lie under the North Sea. The Southern North Sea basin was the first to be explored, and has subsequently proved to contain large gas reserves in the Permian sandstones similar to those of Slochteren. Five commercial gas fields have been put on production and eighteen other gas strikes have been made in UK waters. Not all are of commercial proportions, but none can apparently be developed, largely due to the low prevailing gas price negotiated with the monopoly buyer, the British Gas Corporation. Several gas fields have been found off the Netherlands and one of these is currently being developed. The high continental prices will encourage further development here. So far, 379 exploration and appraisal wells have been drilled in the southern part of the North Sea, including Danish waters, with a success ratio of approximately 1 in 20. The Northern North Sea is predominantly an oil prospective region of younger geological age and now appears to be one of the most prolific areas, for its size, in the world. The basin covers both Norwegian and UK offshore acreage and so far exploration has been limited to the area south of latitude 62"N. There are three major types of prospect in this basin. In order of increasing age, the first and youngest prospect is in the Lower Tertiary sandstones, of which the Forties Field is an example. The second prospect (although the first discovered) is in the domed and fractured Upper Cretaceous and Danian limestone, typified by the Ekofisk Field. The third major prospect, and the most important, is in the. Jurassic sandstones in the northern part of the basin. as evidenced by the Brent group of oilfields.