Factors Influencing the CO2 Corrosion Pattern of Oil–Water Mixed Transmission Pipeline during High Water Content Period

Abstract

After the oil field enters the high water content period, the oil–water mixed fluid in the mixing system will gradually change into the water-in-oil mixed fluid, while the dissolved CO2 causes the pH value of the mixed fluid to decrease. There is also a certain amount of bacteria in the output fluid, with many factors leading to the intensification in the corrosion of the oil–water mixed system pipeline in the high water content period. To clarify its corrosion law, through the mixed transmission pipeline material, 20# carbon steel, in high water conditions under the action of different single factor dynamic corrosion rate experiments, along with the use of the SPSS method, were used to determine the corrosion of the main control factors. The results show that in the high water content period, the corrosion rate of the mixed pipeline 20# steel gradually increases with the increase in temperature pressure, CO2 partial pressure, SRB content, Ca2+ + Mg2+ content, and Cl− content. The corrosion rate with the CO2 partial pressure and SRB content changes show a strong multiplicative power relationship; with Ca2+ + Mg2+ content, Cl− content changes show a logarithmic relationship, the relationship degree R2 is above 0.98. Through SPSS data analysis software combined with experimental data for correlation degree analysis, it is concluded that the correlation magnitude relationship between each factor and corrosion rate is CO2 partial pressure > SRB content > Cl− content > Ca2+ + Mg2+ content > temperature pressure, which provides a theoretical basis for the corrosion protection of an oil gathering pipeline.

Mechanism and anti-corrosion measures of carbon dioxide corrosion in CCUS: A review

“…For instance, due to the high cost of complete purification, the captured CO 2 fluid usually contains corrosive impurities, which can interact with CO 2 , forming more corrosive compounds and exacerbating corrosion. 50 Pipeline corrosion can be attributed to a variety of physical and chemical factors, including environmental conditions, materials used, and more ( Figure 5 ). Corrosion of pipeline steel often results in decreased strength and ductility, ultimately leading to pipeline ruptures or leaks.…”

“…Consequently, the resulting corrosion product film becomes less compact, rendering it less effectively prevent corrosion. 50 It should be noticed that the water content should be rigorously controlled when transporting CO 2 at low temperatures and relatively low pressures. 57 Therefore, meticulous monitoring and control of moisture content, coupled with the implementation of appropriate corrosion control measures, are of paramount importance in ensuring the long-term reliability of equipment and pipelines.…”

“…In the high water content period of oil-water mixed transportation pipeline, with the increase of CO 2 partial pressure, the corrosion rate of 20# steel in the mixed pipeline gradually increases. 50 In magnetite (Fe 3 O 4 ) high-density cement-casing steel system, CO 2 and corrosive substances tend to migrate to the cement-casing interface under high pressure, which leads to an increase in corrosion rate compared with that under normal pressure. 85 Sun et al.…”

CO2 Geological Storage and Utilization

“…Yang et al [5] focused on the problem of corrosion intensification in the oil-water mixed system pipeline during a period of high water content. Taking the gathering and transportation system of HH oilfield as an example, 20 # steel was used as the sample, and the dynamic corrosion evaluation experiment was carried out using a high-temperature and high-pressure dynamic corrosion scaling evaluation instrument under different single factors of high water content conditions.…”