The Boulton Field, Block 44/21a, UK North Sea
The Boulton Field was discovered in 1984 when gas was tested from the Lower Ketch Unit, Carboniferous West-phalian C/D, in well 44/21-2. Following appraisal drilling in 1990, the Boulton ‘B’ structure was delineated and a trap confirmed by a combination of up-dip seal against basal Permian shales, and salts and lateral seal against sealing faults and impermeable Westphalian C sediments. A second structure was drilled in the same year, Boulton ‘F’, with gas discovered in the deeper Murdoch Sand Interval of the Westphalian C/D. The two separate structures collectively form the Boulton Field.
Current deliverability from the ‘B’ structure, Lower Ketch Sands is approximately 100 MMSCFD from a single producer. Developed with a minimal platform facility, the gas is delivered to Theddlethorpe Gas Terminal via offshore compression at the nearby Murdoch Field. The reservoir in Boulton ‘B’ comprises a series of channel sands deposited in a braided stream complex flowing predominantly from north to south across an Upper Carboniferous alluvial plain. Sandbody connectivity within the complex fluvial architecture of the Westphalian C is a key control on gas production.