Corrosion Failure Analysis of Conductor in Eastern Oilfield in the South China Sea

YIN Qi-shuai, YANG Jin, SHI Shan-shan, LU Yan, SUN Ting, LI Zhen-kun, WANG Jun-xiang, YANG Yu-ming

Surface Technology ›› 2018, Vol. 47 ›› Issue (11) : 134-141.

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Surface Technology ›› 2018, Vol. 47 ›› Issue (11) : 134-141. DOI: 10.16490/j.cnki.issn.1001-3660.2018.11.020
Surface Failure and Protection

Corrosion Failure Analysis of Conductor in Eastern Oilfield in the South China Sea

  • YIN Qi-shuai1, YANG Jin1, SHI Shan-shan1, SUN Ting1, WANG Jun-xiang1, YANG Yu-ming1, LU Yan2, LI Zhen-kun2
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Abstract

The work aims to determine the corrosion type of conductor in this oilfield, analyze the corrosion features and direct the anti-corrosion measures by investigating the corrosion failure of conductor in eastern oilfield of the South China Sea and then improve the production status, extend the production life and increase the capacity of oil well. Firstly, from the preli?minary judgment on macroscopic analysis of abandoned conductor, the materials, micro-corrosion morphology, corrosion extent and corrosion product of conductor were analyzed. The mechanical properties, chemical composition and microstructure of conductor in eastern oilfield in the South China Sea all met the API Spec 5L standard. The SEM and morphology photos showed that the corrosion of outer wall was much serious than that of inner wall. The corrosion of inner wall was slight and basically uniform. Local corrosion occurred on the outer wall, the pitting depth was about 115 μm and the minorcrack with width of 150 μm appeared. The X56 conductor was tend to SCC. From EDS analysis, main elements of corrosion products were Fe and O and the mass of them was more than 75%. XRD analysis determined the main ingredients of corrosion products as γ-FeO(OH). Compared the corrosion morphology of conductor pendants with and without anti-corrosion coating, alloy and organic anti-corrosion coating had good anti-corrosion effect and could effectively prevent the corrosive medium from contacting the ontology of conductor and avoid corrosion. The corrosion process of conductor in the sea oil fields mainly oxygen corrosion. The corrosion on inner wall is uniform and slight. Outer wall has local corrosion and micro crack. Alloy and organic anti-corrosion coating has good anti-corrosion effect and can be promoted to field to extend the production life of oil wells.

Key words

eastern oilfield in the South China Sea; X56 conductor; corrosion failure; morphology; product composition; anti-corrosion

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YIN Qi-shuai, YANG Jin, SHI Shan-shan, LU Yan, SUN Ting, LI Zhen-kun, WANG Jun-xiang, YANG Yu-ming. Corrosion Failure Analysis of Conductor in Eastern Oilfield in the South China Sea[J]. Surface Technology. 2018, 47(11): 134-141

Funding

National Science and Technology Major Project (2016ZX05024-005, 2016ZX05058-004), National Natural Science Foundation of China (51774301, 51434009)
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