Natural gas clean-up from wellhead to UK gas grid
Tom Andrew
Word Count: 2467

Abstract
The report examines the current state and future of natural gas clean-up in the UK. The sources of natural gas in the UK are currently undergoing a large shift, moving from self-produced gas from dwindling North
Sea reserves to pipeline imports from Europe and liquefied natural gas imports from overseas. There is also potential for the UK to start extracting onshore shale gas resources. Natural gas clean-up is a multi-step process with several aims including the removal of water, removal of acid gases such as CO 2 and H2S, and extraction of liquid hydrocarbons for further sale. The merits of different techniques for achieving these goals are discussed. The environmental and economic challenges of natural gas processing are also examined. The environmental impact of natural gas processing is lower than other fossil fuel sources, but there are risks of greenhouse emissions, poisoning, and acid rain from methane and H 2S impurities during leaks or gas flaring, whilst process water can be dangerous unless properly treated. Several economic challenges of clean-up are identified, and the economic impact of increased liquid natural gas imports on the processing industry is discussed.

1. Introduction
Natural gas is a gas mixture consisting of methane, ethane and propane, with smaller quantities of heavier hydrocarbons, carbon dioxide, nitrogen and hydrogen sulfide (Hammer et al., 2000). This mixture must undergo a series of processes with two purposes: removal of impurities and recovery of valuable byproducts. It can then be transferred to a grid system for consumption, typically combusted to produce energy
(DECC, 2014).
The UK natural gas market has changed significantly over the past decade. In 2004, the UK became a net importer of natural gas for the first time, and there has been an