The Effect of Mineral Deposition on CO2 Well Injectivity

Abstract

This paper presents results from laboratory investigations of CO 2 injectivity losses in sandstone cores driven by minerals deposition. Parameters studied includes effect of brine salinity, gas injection rate and rock permeability. The results of the study indicates that mineral precipitation and CO 2 injectivity is indeed dependent on brine salinity. We report that, injecting low salinity water into the core after mineral deposition could recover CO 2 injectivity. Below certain salinity of brine, we observed significant injectivity is lost probably due to clay swelling effects. The results also indicates that mineral deposition depends on the brine displacement rate. We observed low injectivity losses at high gas injection rates. The investigation also revealed that mineral deposition effects depends on intial sandstone core permeability. Injectivity losses are significant in cores with lower initial permeability.

Experimental Investigation of the Mechanisms of Salt Precipitation during CO2 Injection in Sandstone

“…Evidence from laboratory core-flood experiments [14][15][16][17][18][19] and numerical simulations [20][21][22][23] indicate about 13-83% absolute permeability impairment and about 2-15% reduction in porosity. The drying rate, temperature, pressure, solid salt saturation, distribution of precipitated salt in the pore spaces and the petrophysical properties of the reservoir rock are some of the underlying factors of salt precipitation effects [24].…”