 |
| Titel |
δ¹⁸O shifts in water in contact with high volumes of CO2 gas |
| VerfasserIn |
Anssi Myrttinen, Veith Becker, Robert van Geldern, Johannes A. C. Barth |
| Konferenz |
EGU General Assembly 2011
|
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250048507
|
|
|
|
|
|
| Zusammenfassung |
| In CO2 injection projects, for instance in enhanced gas recovery (EGR), it is of vital importance to monitor the fate of injected CO2 in the subsurface, in order to gain better understanding of the development of the geochemistry of the host reservoir. Injected CO2 usually has different isotopic compositions than the water already present in the reservoir, respectively. Therefore, when CO2 mixes with H2O during CO2 injection, an isotope exhange can be expected, with a shift in the isotope values towards the more dominantly present end member values of the CO2 gas. In several studies, δ13C has proven to be a well detectable and promising parameter in such monitoring schemes. However, so far δ18O of both water and CO2 is only beginning to be used as a key parameter in CO2 monitoring. It is assumed, that the varying amounts of CO2 gas in relation to the water can provoque different oxygen isotope shifts in the reservoir water.
Laboratory experiments were set up in order to achieve a better basic understanding in δ18OH2O-CO2 interactions. Experiments were carried out at room temperature, low pressures (1400 mbar) and a CO2:H2O mole ratio of 617:1. First data show that within hours to days a significant negative δ18OH2O shift can be observed. This shift can be significantly enhanced in a dynamic environment induced by a shaker. These results indicate, that as long as enough CO2 has been in contact with water, for a long enough period of time, δ18OH2O data can serve as an indicator of past and present CO2-H2O contact. Furthermore, extrapolation of δ18O and CO2-H2O mole ratio data also holds promise to evaluate the amount of CO2 that has been in contact with reservoir fluids. Future research will demonstrate if these changes can be detected on field scale.
This study was conducted as a part of the R&D programme CLEAN, which is funded by the German Federal Ministry of Education in the framework of the programme GEOTECHNOLOGIEN. |
|
|
|
|
|
|