抄録
Dynamic adsorption tests of petroleum sulfonates were conducted using Berea core to study the effects of average EW of micellar slugs, cosurfactants, oil volume contained in micellar slugs and salinity as main factors which affect adsorption of sulfonates on rocks. The influence of divalent cations removed from the rock surface by ion exchange on sulfonates or micellar slugs were examined, and the correlation between phase behavior investigating fluid-fluid interaction and that of effluent samples including rock-fluid interaction in cores was studied. The effect of preflush of sodium orthosilicate solution was also investigated.
1) More hydrophilic slugs with lower EW showed less adsorption of sulfonates than higher EW slugs. Cosurfactants had the effect to reduce adsorption of sulfonates. More hydrophilic cosurfactants with larger HLB value are more effective to decrease adsorption. Increase of oil volume contained in slugs led to reduction of sulfonate adsorption.
2) Salinity had a great influence on sulfonate adsorption. Especially, salinity of a slug itself and salinity of a polymer solution which interacts with a slug seriously affected adsorption of sulfonates.
3) Microemulsion phase in cores shifted from lower phase to middle or upper phase. These transitions of microemulsion phase are attributed to formation of bonds between divalent cations removed from cores by ion exchange and sulfonates or micelles.
4) Adsorption of sulfonates was reduced considerably by the preflush of sodium orthosilicate solution. The preflush of sodium orthosilicate solution is considered to have the effect to restrain the formation of bonds between divalent cations and sulfonates.
