The Coupling Effect of O₂ and H₂S on the Corrosion of G20 Steel in a Simulating Environment of Flue Gas Injection in the Xinjiang Oil Field.

Xiankang Zhong,Long Chen,Jianjun Liang,Xiaoqin Song,Yanran Wang

doi:10.3390/ma11091635

Xiankang Zhong, Long Chen + Show 3 more

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https://doi.org/10.3390/ma11091635

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Abstract

Flue gas injection for heavy oil recovery has received a great deal of attention, because it is more cost effective than lots of other injection methods. However, the corrosion could occur easily, because the flue gas usually contains corrosive gases such as CO2, H2S, and O2. In this work, the corrosion behaviors of G20 steel in flue gas injection environment simulating Xinjiang oil field (China) were investigated using weight loss measurement and surface characterization techniques. The effect of environments including the O2-containing environment, the H2S-containing environment, and the O2-H2S-coexisting environment on the corrosion of G20 steel in gas phase and liquid phase was discussed. The results show that the corrosion rate of G20 steel in the O2-H2S-coexisting environment is much higher than the sum of corrosion rates of the O2-containing environment and the H2S-containing environment, regardless of the gas phase and the liquid phase. This indicates that there is a coupling effect between O2 and H2S, which can further accelerate the corrosion of steel in O2-H2S-coexisting environment. The results of surface characterization demonstrate that in a typical flue gas injection environment, the corrosion products are composed of FeCO3, FeS, FeO(OH), and elemental sulfur. Elemental sulfur could obviously accelerate the corrosion of steel. Therefore, it can be considered that the coupling effect of O2 and H2S on corrosion of G20 steel in flue gas injection environment is caused by the formation of elemental sulfur in corrosion products.

Highlights

Flue gas injection for heavy oil recovery has received a great deal of attention, because it is more cost effective than lots of other injection methods such as natural gas injection [1]
The corrosion rate in O2 -H2 S-coexisting environment sharply increases up to 0.830 mm/y, which is much higher than the sum of corrosion rates in O2 -containing environment and H2 S-containing environment (Figure 3)
The corrosion rate in the O2 -H2 S-coexisting environment is as high as 0.83 mm/y, which is much higher than the sum of corrosion rates of both the O2 -containing environment and the

Summary

Introduction

Flue gas injection for heavy oil recovery has received a great deal of attention, because it is more cost effective than lots of other injection methods such as natural gas injection [1]. The flue gas as an injectant for enhanced oil recovery is usually composed of multiple components including N2 , CO2 , O2 , H2 S, hydrocarbons, and water vapor. There is high corrosion risk for the surface piping and subsurface tubulars in flue gas injection process. Two main strategies are employed to minimize the potential of corrosion: (I) reduce the oxygen content to a minimum by conducting the combustion in a fuel-rich environment and (II) eliminate the possibility of vapour condensation by ensuring that the flue gas is always above its dew point [2]. The corrosion cannot still be completely avoided, especially during the practical production process that faces the complex environment

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