Analyses of pre-injection reservoir data for stable carbon isotope trend predictions in CO2 monitoring: preparing for CO2 injection

作者：Myrttinen A^*; Becker V; Nowak M; Zimmer M; Pilz P; Barth J A C

来源：Environmental Earth Sciences, 2012, 67(2): 473-479.

DOI：10.1007/s12665-012-1710-3

• Carbon stable isotopes
• Dissolved inorganic carbon
• CO2 injection monitoring
• Equilibrium analyses

Baseline monitoring at the proposed enhanced gas recovery site in Altmark (Germany) was carried out in combination with theoretical and laboratory investigations to describe and predict the principles of expected stable carbon isotope and dissolved inorganic carbon (DIC) trends during CO2 injection in reservoirs. This provides fundamental data for site-specific characterisation for monitoring purposes. Baseline delta C-13 values at the Altmark site ranged between -1.8 and -11.5 aEuro degrees and DIC values were about 2 mmol L-1. These baseline values form the basis for a theoretical study on the influences of the ambient reservoir conditions on the state of geochemical and isotope equilibrium of the reservoir fluids. Transferring this theoretical study to the Altmark site enables predictions on geochemical trends during potential injection. Assuming that CO2 would be injected at the Altmark site to pCO(2) = 100 bar and with a delta C-13 of -30 aEuro degrees, at isotopic and geochemical equilibrium, delta C-13(DIC) values would approach this end-member, and DIC concentrations of 1,000 mmol L-1 would be expected. Laboratory experiments were conducted at low pCO(2) levels (4-35 bars) to mimic the approach of a CO2 plume at a monitoring well. These results support field investigations from other sites: that delta C-13(DIC) is a sensitive tool for monitoring CO2 migration in the subsurface and simultaneously allows quantification of geochemical trapping of CO2.

• 出版日期2012-9