Development geology of the Piper Oilfield

Abstract

The Piper Oilfield lis in the UK Block 1517, 125 miles northeast of Aberdeen, Scotland. The field is situated on a shelf south of the East Shetland platform, and near the eastern end of the Moray Firth Basin. The field was discovered in January 1973 from a seismicly mapped structure and confirmed as a major oilfield during the year with five appraisal wells and one exploratory well. A steel platform with 36 well slots and space for two drilling rigs was centrally located over the field in 474 ft. of water in June, 1975, and made ready for production drilling by October 10, 1976. Commercial production was established December 7, 1976, when the P1 well came on stream at more than 30 000 b/d. Production is currently 290 000 stb/d of 37°C API, low sulphur oil and original recoverable reserves are estimated to be 618 million barrels. Production is from the Upper Jurassic Piper Sandstone, a high-energy, marginal marine and marine, shallow, shelf sandstone with gross thickness of 165–454 ft. The field comprises three parallel, tilted fault blocks on the north edge of the Witch Ground Graben. Blocks I and II cover 7149 productive acres and have oil columns of 1312 ft. from 7200 ft. subsea to a common oil-water contact at 8512 ft. subsea. Block III to the southwest borders the Witch Ground Graben and contains a small accumulation with separate oil-water contact at 9199 ft. subsea. A combination of favourable geological and engineering conditions together with extensive use of seismic data before and during development drilling has resulted in high production rates and the need for only one centrally located platform to maximize the recoverable reserves from Piper oilfield.