THE SYNERGISTIC / ANTAGONISTIC EFFECT OF WATER TREATMENT CHEMICALS ON CORROSION INHIBITION OF CARBON STEEL IN THE WATER INJECTION SYSTEM OF WEST KUWAIT OIL FIELDS

摘要

This study evaluated the corrosion inhibition of three corrosion inhibitors and particularly the influence of their complementary biocide and scale inhibitors to treat aquifer and effluent brines used in water injection systems of West Kuwait oil fields. The Rotating Cylinder Electrode (RCE) test was first used to measure the performance of the chemicals under shear conditions. The best two performing inhibitors were then tested in an autoclave to observe their performance under actual system pressure and temperature. In the RCE test the biocide and the scale inhibitors from each supplier decreased the effectiveness of the corresponding corrosion inhibitor packages for the two brines. However, a fatty amines corrosion inhibitor and a quaternary amines corrosion inhibitor and their corresponding biocide/scale inhibitor packages showed better protection and therefore were selected for the autoclave tests. The autoclave test results indicated that both of the selected corrosion inhibitor/scale inhibitor/biocide packages performed well at higher pressure and acid gas exposures. The fatty amine corrosion inhibitor and its associated biocide/scale inhibitor provided 95% and 90% protection in the aquifer and effluent waters, respectively; whereas the quaternary amines corrosion inhibitor and its associated biocide/scale inhibitor provided 96.5% and 94.5% protection in the aquifer and effluent waters, respectively. It is suggested that under the autoclave conditions, which more closely resemble field conditions, the biocide and scale inhibitors do not reduce the inhibitory activity of the corrosion inhibitor in the two waters as much as under RCE conditions. Based on these results both systems are considered viable candidates for further trials examining scale inhibition, biocide activity and field trials in these water systems.