The Beryl Field, Block 9/13, UK North Sea

Abstract

Abstract The Beryl Field, the sixth largest oil field in the UK sector of the North Sea, is located within Block 9/13 in the west-central part of the Viking Graben. The block was awarded in 1971 to a Mobil operated partnership and the 9/13-1 discovery well was drilled in 1972. The Beryl A platform was emplaced in 1975 and the Beryl B platform in 1983. To date, ninety-five wells have been drilled in the field, and drilling activity is anticipated into the mid-1990s. Commercial hydrocarbons occur in sandstone reservoirs ranging in age from Upper Triassic to Upper Jurassic. Structurally, the field consists of a NNE orientated horst in the Beryl A area and westward tilted fault blocks in the Beryl B area. The area is highly faulted and complicated by two major and four minor unconformities. The seal is provided by Upper Jurassic shales and Upper Cretaceous marls. There are three prospective sedimentary sections in the Beryl Field ranked in importance as follows: the Middle Jurassic coastal deltaic sediments, the Upper Triassic to Lower Jurassic continental and marine sediments, and the Upper Jurassic turbidites. The total ultimate recovery of the field is about 800 MMBBL oil and 1.6 TCF gas. As of December 1989, the field has produced nearly 430 MMBBL oil (primarily from the Middle Jurassic Beryl Formation), or about 50% of the ultimate recovery. Gas sales are scheduled to begin in the early 1990s. Oil and gas production is forecast until licence expiration in 2018. The Beryl Fields is located 215 miles northeast of Aberdeen, about 7 miles from the United Kingdom-Norwegian boundary. The field lies within Block 9/13 and covers and area of approximately 12 000 acres in water depths ranging from 350-400 ft. Block 9/13 contains several hydrocarbon-bearing structures, of which the Beryl Fields is the largest (Fig. 1). The field is subdivided into two producing areas: the Beryl Alpha area which includes the initial discovery well, and the Beryl Bravo area located to the north. The estimated of oil originally in place is 1400 MMBBL for Beryl A and 700 MMBBL for Beryl B. The fiel has combined gas in place of 2.8 TCF, consisting primarily of solution gas. Hydrocarbon accumulations occur in six reservoir horizons ranging in age from Upper Triassic to Upper Jurassic. The Middle Jurassic (Bathonian to Callovian) age Beryl Formation is the main reservoir unit and contains 78% of the total ultimate recovery. The field was named after Beryl Solomon, the wife of Charles Solomon, who was president of Mobil Europe in 1972 when the field was discovered. The satellite fields in Block 9/13 (Nevis, Ness and Linnhe) are named after Scottish lochs.