Unusual Oilfield Corrosion Inhibitors

Abstract This paper summarizes a laboratory study of unusual corrosion inhibitors subjected in kettle tests to conditions that might exist in the oilfield. Some corrosion inhibitors are compounds with another primary function. Quaternary ammonium compounds are in this group; the primary function is often biocidal but under the right conditions, substantial corrosion inhibition is observed. Tetrakishydroxymethyl phosphonium sulfate (THPS) is another compound frequently used for its biocidal properties. Under certain conditions THPS is a corrosion aggravator, under others it is an effective inhibitor. Calcium ions alone are not corrosion inhibitors. However, some inhibitors are considerably more effective when calcium is present in the corrosive brine. Some inhibitor/corrosive systems are not influenced. This system was examined for trends. Other unusual corrosion inhibitors are tabacco extract and molasses. These materials were examined earlier in acid and in cleaning systems, but this paper examines inhibitive properties under conditions representative of oilfield corrosion. Although few of the above substances are likely to be used alone as practical corrosion inhibitors, the information presented in this paper is useful to corrosion engineers dealing with oilfield corrosion. For example, further study might show tobacco extract to be a low cost component for corrosion inhibitor formulations.