Microgravimetric differential control of a CO2 injection experiment in coal
The storage of greenhouse gases is an active research field. In this project, an injection of CO2 into a coal seam from an underground coal mine in Asturias (Spain), is performed. Different monitoring methodologies are employed to follow the fluid propagation inside the porous medium and the induced changes.
Our group employs Microgravity. The gas entrance in the porous médium displaces the already existing fluids and changes the microstructure. This variations generates density changes that, in turn, modify the value of gravity in the surrounding area. This is the first time, to our notice, that this minute changes are subject to monitoring from the interior of an underground mine at around 500 m. b.s.l.
It is a technical and logistic challenge to achieve to get the pertinent measures displaying profiles which are hundreds of meters long along the galleries keeping precision under 10 microgal. Singular topographical positioning methods, transportation means and gravity positioning strategies have been devised adapted to these hostile conditions.
The obtained gravity measurements should provide information about the gas movement inside the seam. This information might be used as prior information to a hypothetical inversion procedure applied to a multiphase flow problem.
The capability of taking gravity measurements underground extends the 3D coverage compared to those surveys only having surface observations. These might improve the estimation of parameters with geological/mining interest.
The Project is still alive.