The Nelson Field, Blocks 22/11, 22/6a, 22/7, 22/12a, UK North Sea

Abstract

Abstract The Nelson Field is located in Blocks 22/11, 22/6a, 22/7 and 22/12a in the UK Central North Sea. Nelson is a simple dip closed structure and is one of a series of Palaeocene Forties Sandstone Member oil accumulations situated on the Forties-Montrose High. The first exploration well on the prospect, 22/11-1, was drilled by Gulf Oil in 1967. Although hydrocarbon shows were encountered in a heterolithic section of Forties Sandstone Member, the well failed to flow on test and was abandoned. 3D seismic data were first acquired in 1985 and led to the discovery of Nelson in 1988 when the 22/11-5 well was drilled by Enterprise Oil plc. Following appraisal drilling, Nelson was granted production consent and the field came on-stream in February 1994. The hydrocarbon type is a light 40° API crude with a GOR of 555 SCF/BBL and is believed to be sourced from the East Forties Basin. The Nelson Field is developed from a 36 slot minimum facilities platform. Currently there are 23 platform producers, four sub-sea producers and four platform water injectors. Oil export is via the Forties Pipeline System and gas export is via the Fulmar Gas System. Oil originally in place is estimated at 790 million barrels of oil (MMBBL). Up to end-1999, the field had produced 261 MMBBL. Since the field was described by Whyatt et al. (1992), a further 28 wells have been drilled resulting in the collection of a considerable amount of new geological and geophysical data. This now includes a total of 6500 ft of Palaeocene core and 4D seismic data. This has enabled a more detailed understanding of the structure and sequence stratigraphy of the Nelson Field. This paper illustrates the importance of seismic mapping, high resolution biostratigraphy and sedimentology in developing the Nelson Field model.