The South Morecambe Gas Field, Blocks 110/2a, 110/3a, 110/7a and 110/8a, East Irish Sea

South Morecambe Gas Field is situated in the East Irish Sea and produces gas from the Triassic Sherwood Sandstone Group. Exploration of the basin commenced in 1966 and the discovery well, 110/2-1, was drilled in 1974. Appraisal was complete by 1983 and development was carried out in two phases with the object of providing deliverability to help to satisfy the winter peak in demand. First gas was produced in January 1985 and production during the winter can be sustained at 50MMCMD (1750mmscfd). The stratigraphic succession of the East Irish Sea Basin (EISB) consists of Carboniferous (Dinantian to Westphalian) strata unconformably overlain by 15000 to 20000 feet of continental Permo-Triassic strata. The Triassic Sherwood Sandstone Group contains reservoir rocks and the overlying Mercia Mudstone Group evaporites provide a seal. Seismic cover of the area includes 2D and 3D data, the latter providing good images that form the basis of the current structural interpretation. The structural development of the basin commenced with extension in the Permo-Triassic followed by inversions in the late Jurassic and early Tertiary. The reservoir has been zoned using a scheme that recognizes primary depositional facies as the main criterion for correlation. The petrophysical evaluation has introduced new methods of calculating porosity, S w and net pay. The latest reservoir pressure data has been used in a material balance study and a two tank simulation model, both give GIIP estimates which are in line with earlier estimates. The new petrophysically derived reservoir parameters were also used to make a volumetric estimate of GIIP. Remaining recoverable reserves are at least 3 Tcf.