What is the RECOPOL project?

Carbon dioxide (CO₂) is the main greenhouse gas emitted by human activity. It is held responsible for climate change, one of the major environmental issues of our time. In the future, we hope that renewable energy (e.g. wind and solar energy) will become important source of energy. Until that time however technologies are required that will allow us to use fossil fuel (coal, oil, gas) in an environmentally friendly manner. One of the most promising techniques to reduce greenhouse gas emissions is underground storage of CO₂. The RECOPOL project is an EU co-funded combined research and demonstration project to investigate the possibility of permanent subsurface storage of CO₂ in coal. The project started in November 1 2001.
RECOPOL stands for: 'Reduction of CO₂ emission by means of CO₂ storage in coal seams in the Silesian Coal Basin of Poland'.

At a selected location in Poland a pilot installation is developed for methane gas production from coal beds while simultaneously storing CO₂ underground. The produced methane could become an alternative fuel that can be locally produced in Silesia. This installation is the very first of its kind in Europe, and at the moment the only one operational worldwide.

What is being done?


CO₂ is brought in by trucks and stored on site in liquid form (at a temperature of -20 º C) in two containers. The CO₂ is heated and than by a pump injected into underground coal seams at a depth of 1050-1090 m, several hundreds of meters below the deepest mine workings of the Silesia mine. The CO₂ will adsorb to the coal, which will release its methane gas simultaneously. This methane will be produced from the second well, with the pumpjack. Injection and production will take place from June 2004 to December 2004. It is planned to inject up to 1,000 tonnes of CO₂ totally, which is about 10% of the yearly CO₂ emission from a typical mine. The RECOPOL project is being implemented by an international consortium. The field demonstration experiment is the first of it's kind outside Northern America.

An open workshop was held to present results of the RECOPOL project. Please click here for further details.

CO₂ injection

After the development of the pilot site in 2003, injection tests in the newly drilled well started in summer 2004. The principal targets for CO₂ injection are coal seams between 1 and 3 m thick of Carboniferous age in the depth interval between 900-1100 m. Several actions were taken to establish continuous injection, which was eventually reached in April 2005, following a frac job of the coal seams. Stimulation was required because the permeability of the coal seams reduced in time, presumably due to swelling as the result of contact with the CO₂. Similar observations were made in Canada and the United States, where they were also attributed to swelling of the coal seams. After fraccing circa 12-15 tonnes per day were injected in continuous operation from late April to early June. In total circa 760 tonnes of CO₂ were injected between August 2004 and the end of June 2005.

Cumulative amount of injected CO₂ in time in the RECOPOL project

Gas production

An existing coalbed methane production well at circa 150 m distance was cleaned, repaired and put back into production at the end of May 2004, to establish a baseline production. Gas was produced from the production well to evaluate possible enhancement of the gas rates. The anisotropy of the permeability due to the cleat orientation was thought to hamper an early breakthrough, because the highest permeability is perpendicular to the flow direction. Unexpectedly, a slow rise in the CO₂ content in the production gas was observed since November 2004 which could be attributed to the injected CO₂. In addition, a decrease in total gas production was observed during longer fall off periods in the injection well. This indicates a clear response of the production well on the injection activities. In April 2005, after stimulation of the injection well, the gas production increased rapidly after a few days. The CO₂ concentration in the production gas also rapidly increased, clearly indicating the breakthrough of the gas. However, the amount of daily produced CO₂ was much lower than the amount of daily injected CO₂, indicating a clear sink of CO₂ in the reservoir. This was confirmed by the rapid decrease of production rates after continuous injection stopped in June 2005. The concentration of methane in the production gas, initially around 95%, dropped significantly after the breakthrough of CO₂ in April 2005. Nevertheless, first evaluation of the data indicates that the absolute amounts of CH4 that were produced are significantly higher than the baseline production with conventional production. Shut-in tests of the production well in June 2005 showed that the reservoir pressure around the production well was slightly increased due to the injection. Probably, the pressure in the reservoir will decrease once the CO₂ will be adsorbed on the (undersaturated) coal. The gas that was produced after the shut-in test showed a significant increase in the methane concentrations, indicating that the exchange of CO₂ for methane is taking place in the reservoir. However, it appears that sufficient time is required to allow for diffusion of the gas into and out of the coal matrix. Along with the field activities, an extensive monitoring programme has been set-up to detect any possible, but unlikely, leakage of CO₂ to the surface or the adjacent mine. Continuation of the monitoring programme in the next months is currently under evaluation.

Preliminary conclusions

Several months of injection showed that injection without stimulation is difficult under the local field conditions. The injected amounts after stimulation of the injection well provide a good basis for a future upscaling of the operations. The consortium showed that it is possible to set up an on-shore pilot in Europe and to handle all “soft” issues (permits, contracts, opposition, etc.) related to this kind of innovative projects. The lessons learned in this operation can possibly help to overtake start-up barriers of future CO₂ sequestration initiatives in Europe.