Experimental investigation of supercritical methane injection in oil fields on salt deposit formation by gas anti-solvent process

Salt precipitation and salt block formation are the common problems in the gas injection wells. The salt precipitation may produce a severe loss of well injection which leads to a complete blockage of injection. The wells which located at south oil field of Iran are faced with such problems. The analysis of produced sediments shows that more than 93% of those compounds are sodium chloride (NaCl). Different mechanisms can affect the formation of deposit. By injecting supercritical methane into oil fields, it was proved that one of the most probable mechanisms in such condition is gas anti-solvent. In this work, two formation waters at different temperature and pressure conditions were evaluated. The results showed that significant amount of precipitation was observed in one of those water formations while in the other one no precipitation was detected. Furthermore, the effect of operating variables including temperature and pressure on the quantity of formed deposit has been investigated. Moreover, the obtained experimental results were simulated using the PHREEQC software. (C) 2013 Elsevier B.V. All rights reserved.