Study on the Influence of OTAC-Type Corrosion Inhibitors on the Organic Chlorine Structure and Content in Crude Oil

The use of chemical additives in tertiary oil recovery will increase the organic chlorine structure and content of crude oil, leading to significant economic losses and safety hazards for oil companies. This study aims to evaluate the feasibility of large-scale application of OTAC-based corrosion inhibitors in oil extraction environments. Gas chromatography-mass spectrometry (GC/MS) was utilized to analyze crude oil samples from three distinct oil wells within an oil field. The study examined the structural and compositional changes of organic chlorides in the samples before and after the addition of OTAC-type corrosion inhibitors. The results indicate that the effect of the OTAC corrosion inhibitor on the organic chlorine content in crude oil varies among the different wells. In addition to the introduction of OTAC, chlorinated alkanes and chlorinated ethers were also included. Specifically, when the primary organochlorine component of the oil sample is sulfonyl chloride, the application of this corrosion inhibitor will introduce the organochlorine compound OTAC and significantly decrease the sulfonyl chloride content from 7.39% to 0.90%. This change results in a reduction of the total organochlorine content from 9.66% to 6.84%. Conversely, when the primary organic chloride was categorized as chlorinated alkyl esters, the addition of the inhibitor led to the formation of two new components: chlorinated alkanes and chlorinated ethers. This results in an increase in the total organic chlorine content from 3.29% to 5.30%. Moreover, in cases where the primary organic chlorine components of the oil sample are chlorinated alkyl esters, unsaturated chlorinated hydrocarbons, and sulfonyl chlorides, the use of this corrosion inhibitor will lead to the disappearance of unsaturated chlorinated hydrocarbons and the formation of chlorinated alkanes. Consequently, the total organic chlorine content decreases slightly from 2.33% to 2.04%. The findings of this study can offer theoretical guidance for the practical application of OTAC-type corrosion inhibitors in the field.