Experimental investigation of inhibitors injection to control salt precipitation using wetted wall column

Abstract

Dry gas injection into wells will vaporize unwanted water, causing salt precipitation. The vaporization starts from the well base and proceeds outward. The salt precipitation may produce a severe loss of gas injection, which eventually results in a complete blockage of injection. The wells which are located in south oil field of Iran face such problem. The analysis of produced sediments shows that the majority of those compounds are sodium chloride (NaCl). This paper discusses the advantages of applying salt inhibition to reduce mass transfer between gas and water. This concerns an experimental study of the effect of inhibitor addition on the NaCl precipitation. A pilot-scaled dynamic loop was developed to test the performance of NaCl formation and inhibition. Experiments were performed by injecting natural gas into the pilot test apparatus in which formation water flows down the wetted wall column. The amount of evaporated water is measured and represents the amount of precipitated salt. In this work, sodium dodecyl sulfate (SDS) and polyethylene glycol (PEG) used as inhibitors have been investigated for application in halite scaling that was produced by evaporation mechanism. The experiments show that both substances (SDS and PEG) have been effective in reducing the quantity of salt precipitated. Furthermore, it shows that SDS is more efficient than PEG, and the optimum SDS concentration in solution is 400 ppm to inhibit halite formation.