Experimental Study of CO2 Injection with SO2 Impurities in Depleted Gas Fields in Northeast Netherlands

The aim of this experimental study is to evaluate the effects of impure CO2 injection on potential storage sites in northeast Netherlands. The reservoir in these fields is Permian Rotliegend sandstone, overlain by Zechstein carbonates, anhydrites and salt. Medium-term (30 days) laboratory experiments have been carried out by injection of CO2 and 100 ppm SO2 in reservoir/seal core samples. Following injection and subsequent formation of sulfuric acid, dissolution of feldspar and dolomite minerals was observed. Most of the SO2 was immobilized and trapped by anhydrite precipitation. Permeability measurements of the samples before and after the experiment showed that permeability in reservoir samples increases by factors between 1.2 and 2.2. In the caprocks, the samples with higher percentage of carbonate minerals show increase in permeability but higher anhydrite content of samples causes permeability reduction.