Production of associated gas" from the mixed oil and gas fields located principally in the northern and central North Sea has varied over time for a number of reasons. The rate of production is affected by contractual nominations, by planned and unplanned maintenance, by the effect of investment in new production or injection wells or well workovers in existing fields, by the effect of past production reducing reservoir pressure in existing fields and by the effect of new fields coming into production. Total associated gas production from the UK continental shelf peaked in 2002 and has since declined. Production from new fields coming on-stream has not matched the decline in production from existing fields, though there have been significant changes from month to month. Production in August 2005 was particularly low, with reduced deliveries at all four of the main coastal landing terminals (CATS, FLAGS, SAGE and SEAL), but by October production was back close to the level of a year earlier.