Nitrogen Rejection for the North Morecombe Project

British Gas (BG) discovered the Morecambe Bay Gas Field in the Irish Sea, off the coast of Lancashire, in the early 70's. Detailed investigations revealed that the 6-7 trillion standard cubic feet (SCF) field was in fact split into two (ie North and South). The South field (approx 5 trillion SCF) was developed in two phases through the 80's and became operational in 1985 and 1990 respectively.This particular project concerns the development of the North field.The North Morecambe Gas Field contains 1½- 2 trillion SCF and its development entails construction of an offshore platform, on offshore pipeline and a new onshore terminal at Barrow, just 90 metres North of the existing South Morecambe Terminal. The field is owned and operated by a BG subsidiary company - British Gas Exploration and Production Ltd, and the project is being managed by a team from the BG Group Service Construction Division.The offshore platform is a piled steel jacket and topside (unmanned), comprising 12 well positions (with provision for two future satellites) and the gas is carried the 25 miles ashore by a 36" pipeline. The new terminal site at Barrow has full processing capabilities (described later) and is approx 800 metres x 200 metres in area.The project is on a very tight time timescale of 3½ years and is due for operation in October 1994, at a cost of about £600 millions.During the feasibility studies in 1988, it was identified that in order to obtain the correct calorific value or Wobbe number for exporting the gas from the North Morecambe Field into the BG National Transmission System (the network of pipes and pumping stations, around the UK, delivering gas to BG customers), it was necessary to remove some of the nitrogen.