Exploration for gas in the Irish area

Abstract

Exploration for gas between the Isle of Man and the mainland has confirmed the presence of a Permo-Triassic basin, with sediment thicknesses in excess of 3,000 m. The section can be correlated with the onshore succession and consists of the following: 'Keuper' Marl + Saliferous series (eroded), 'Keuper' Waterstones, 'Keuper' Sandstone, St. Bees Sandstone Manchester Marl and equivalent halite Collyhurst Sandstone and equivalent shales. Drilling and seismic work have shown abrupt thickness changes across some faults, which may show reversals of throw at different times. Sonic velocities in shales at the base of the 'Keuper' Marl suggest depths of burial of more than 4000 m, pointing to the possibility that a thick younger Mesozoic section was once present. Diagenesis of the sandstones includes calcite and quartz cementation and the development of platy illite. Gas has been found by Hydrocarbons Great Britain Limited, a subsidiary of British Gas Corporation, in sandstones of the 'Keuper' Waterstones, 'Keuper' sandstone and top part of the St. Bees Sandstone.