Feb 27, 2009
Gas field cleans up carbon dioxide
Injecting carbon dioxide into rock formations deep underground could be beneficial in more than one way. As well as removing greenhouse gas from the atmosphere and mitigating global warming, carbon capture programmes could help to increase oil and gas yields. The technique is already tried and tested on oil fields, but it is still early days for gas. This year a new pilot project will investigate the feasibility of using carbon capture to push more gas down the pipeline.
Starting in spring 2009, carbon dioxide will be injected into Europe’s second largest natural gas field – the Altmark – just south of the town of Salzwedel in northern Germany. Financed by the German Ministry for Education and Research, CLEAN (Carbon dioxide Largescale Enhanced gas recovery in the Almark Natural gas field) is a co-operative effort between research centres, universities and industry.
It won't be the first project of its kind – Gaz de France Production Nederland B.V. has been operating a similar project since January 2007 at the K12B gas field, just off the Netherlands, in the North Sea. But it will be the first project to make its findings widely available. "K12B is an industry project and very little is known about it," says Michael Kühn from the German Research Centre for Geosciences at Potsdam, who is co-ordinating the new study.
Over the course of the experiment around 100 000 tons of carbon dioxide will be captured from nearby gas power stations (operated by Vattenfall), and pumped into the Altensalzwedel field, part of the Altmark range. The carbon dioxide will be captured using oxy-fuel combustion – burning the fuel in oxygen rather than air. This produces flue gases that are almost pure carbon dioxide, which can be piped off directly.
Like all natural gas fields, Altensalzwedel has a proven ability to store gas, with a cap rock that has enabled gas to accumulate for millions of years. However, Kühn and his colleagues will be monitoring for any carbon dioxide leaks, in particular from the network of old wells.
They will also be assessing how effective the carbon dioxide is at re-pressurising the reservoir and forcing the remaining pockets of natural gas out. Around 78% of the natural gas has already been produced, but it is hoped that the carbon dioxide will help to recover the final 22%.
Kühn and his colleagues will be monitoring many variables including the temperature, pressure, microbiology and geochemistry inside the reservoir and the flow of methane leaving the reservoir. "We want to find out if enhanced gas recovery works in the Altmark, and to discover how carbon dioxide behaves within the reservoir with regard to storage potential," Kühn told environmentalresearchweb.
Computer models and calculations indicate that the process should lock up more carbon dioxide than it produces. The IPCC report from 2005 estimated an 85% reduction in carbon dioxide emissions using this technique. Kühn and his colleagues will be passing their findings on to scientists at the Potsdam Institute for Climate Impact Research, to assess whether the benefits of storing the carbon dioxide are outweighed by the carbon dioxide produced when burning the extra methane that was recovered.
If the project is a success then there are many natural gas fields worldwide that the technique could be applied to.
About the author
Kate Ravilious is a contributing editor to environmentalresearchweb.