| With the technology of C02-enhanced oil recovery widely used, the problems of CO2 corrosion in gathering and transportation pipeline become more and more noticeable. So far, the inhibition effects of crude oil are generally not taken into account in control measures for CO2 corrosion, resulting in economic waste. The inhibition mechanisms of crude oil include covering effect, contributing to the formation of dense corrosion film and forming water-in-oil emulsions. This paper studies on the effect of oil film and emulsions on corrosion rate, when no corrosion product film formed. Research is divided into four parts:the impact of stability of emulsions on corrosion, the impact of oil film and oil-in-water emulsions on corrosion, the establishing of safe transportation model and the droplets settling monitoring experimental of water-in-oil emulsions. And the following conclusions have obtained:shorter emulsifying time and higher water cut make emulsion more corrosive; Once the emulsion phase inversion (from water-in-oil type to oil-in-water type)or oil and water separation occurs, corrosion rate will soar; oil film and oil-in-water emulsions also can inhibit corrosion significantly, but the duration of inhibition doesn’t exceed for one hour under this certain experimental conditions; under laminar flow state, conveying speed can be guided by safe transportation model, and the corrosion position can be roughly determined; the time of droplets settling is determined by droplets settling monitoring experimental, it is close to the safe transportation time, indicating that the safe transportation model is applicable and reliable. Thus, it is considered that if oil and water could be mixed to emulsion, the pipeline wouldn’t contact with water directly and the corrosion of the bottom of pipeline could be inhibited. And under laminar flow condition, the safe conveying speed can be determined by safe transportation model. |
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