Volume 42, Issue 4

The fundamental process of drilling within the oil and gas industry appears straightforward, entailing the creation of a borehole that connects to the underlying oil reservoir. An indispensable component in this operation is the mud formulation, playing a critical role in lubricating the drill bit and facilitating the efficient removal of cuttings. However, a notable challenge arises due to the machinery’s predominantly metal composition, leading to corrosion concerns. Various strategies, including the application of corrosion inhibitors, have been introduced to address and manage this corrosion challenge. This review provides a comprehensive exploration of recent research endeavors focused on corrosion inhibitors in the context of offshore drilling operations. It aims to offer insights into the diverse types of corrosion commonly encountered during drilling activities in marine environments. Moreover, the review delves into an in-depth examination of various corrosion inhibitors utilized for mitigation, shedding light on their performance characteristics and limitations within the specific scope of drilling operations. By scrutinizing these corrosion inhibition strategies, the review contributes to a nuanced understanding of the evolving landscape in drilling technology and the measures taken to ensure the longevity and efficiency of drilling equipment.

CO 2 geological utilization and storage (CGUS) is a key technology to achieve carbon neutrality goals. To apply CGUS on a larger scale, the issue of steel corrosion during the process must be addressed to mitigate technological risks. This paper provides an overview of CO 2 -induced steel corrosion mechanisms and identifies factors that influence corrosion. The impact of CO 2 partial pressure, temperature, salinity, pH, impurities, and fluid flow on steel corrosion behavior are also discussed. With the presence of water, the corrosive effect of supercritical CO 2 on steel is stronger than that of dissolved CO 2 or gaseous CO 2 . As the temperature increases, the corrosion rate of steel first increases and then decreases. Increasing salinity and decreasing pH lead to an accelerated corrosion rate of steel. Corrosion inhibitors, coatings, and corrosion-resistant alloys are recommended protective measures against CO 2 -induced corrosion. Compared with coatings, corrosion inhibitors and corrosion-resistant alloys are more commonly used in CGUS projects. Future research directions include further exploration of the mechanisms underlying CO 2 -induced steel corrosion, clarifying the coupled effects of various environmental factors, and developing corrosion protection technologies under high-pressure and high-concentration CO 2 conditions.

The effect of the recrystallization degree on the properties of passive films formed in 0.1 M HNO 3 solution for super ferritic stainless steel S44660 was examined in this study. The initial specimens, in their cold-rolled state, showed a high dislocation density, as observed through electron backscatter diffraction (EBSD) experiments. Analysis of potentiodynamic polarization (PDP) curves and electrochemical impedance spectroscopy (EIS) measurements suggested that with the increase of recrystallization degree, the corrosion current density reduced and the corrosion potential increased. As revealed by Mott–Schottky analysis, the passive film showed a dual structure of n-type and p-type semiconductors, with the carrier density of the passive film decreasing as the recrystallization degree increased. X-ray photoelectron spectroscopy (XPS) provided insights into the film composition, indicating that the Fe 2 O 3 and Cr 2 O 3 content, which improved the stability of the passive film, increased with the degree of recrystallization. In summary, the increase in recrystallization degree reduced the number of defects in the microstructure, thereby creating favorable conditions for the formation of highly protective passive films. The passive film formed after complete recrystallization exhibited enhanced corrosion resistance.

Aged oil pipeline production systems, historically designed without corrosion protection due to predominantly oil-wetted conditions, now face significant changes as increased water content in produced oil arises from field maturation. This work investigates the corrosion inhibition properties of sweet crude oil on carbon steel 1018 in a CO 2 -saturated NaCl solution using electrochemical testing (open circuit potential, polarization resistance, electrochemical impedance, potentiodynamic polarization) and surface characterization (SEM, EDS) techniques at 50 °C and pH 6. Carbon steel specimens were immersed in crude oil for durations ranging from 0 to 144 h before undergoing corrosion testing. Results showed that a 144-h immersion in crude oil led to an 88 % reduction in corrosion rate, comparable to the efficiency of standard quaternary ammonium-based inhibitors. Furthermore, a semi-empirical model predicting uniform CO 2 corrosion rates for varying oil immersion durations is proposed and validated by comparing its predictions with experimental data from the electrochemical tests.

Organic–inorganic hybrid coating has been applied on metallic corrosion protection effectively. Molybdenum disulfide (MoS 2 ) nanosheets with graphene-like two-dimensional lamellar structure were an anticorrosion inorganic additive, rendering the organic coating better corrosion resistant. However, the aggregation and poor solubility are still current issues that should be addressed. Functionalization MoS 2 nanosheets with surface modified by polydopamine (PDA) and silane coupling agent (KH560) were prepared in polyurethane (PU) composite coatings to obtain dense and intact multilayer network structure coatings for corrosion protection. KH560-PDA-MoS 2 /PU coating with crosslinked polymer network structure has a high impedance modulus, large contact angle, and strong hydrophobicity. The coating meets the national technical standards for salt spray testing and nitric acid (HNO 3 ) titration testing, demonstrating excellent corrosion resistance.

The microstructure of three rolling surfaces of TC4 sheet is different, and their resistance ability to hydrogen damage lacks systematic research. Thus, the hydrogen damage behavior of TC4 rolling sheet was investigated in this paper. The hydrogen diffusion law along different rolling directions and the precipitation of hydrides on different rolling surfaces were compared. It is found that the shape and distribution of α and β phases are changed under the action of extrusion force during the rolling process, and they are arranged in striped shape on the R-N surface along the R direction, and the diffusion of hydrogen along the R direction is faster due to the existence of continuous β phases as hydrogen diffusion channels, resulting in the more serious hydrogen damage. Besides the hydrides mainly deposited at the α and β phase boundaries, the hydrides precipitated in the interior of α phases on the R-N surface are more than that on the R-T surface due to the different distribution state of β phases.

A silica/aminated kaolin (SiO 2 @AK) composite was prepared by modifying kaolin and loading silica, using intercalation complex method and sol–gel method. Quantitative composites were dispersed in epoxy resin to obtain a silica/aminated kaolin/epoxy resin composite coating (SiO 2 @AK/EP) on stainless steel. The results showed that the thickness of the dry coating was approximately 110 ± 10 μm, and the surface was flat without evident agglomeration. As the SiO 2 @AK composite was introduced, the water contact angle increased from 40° to 88°, the average surface roughness of the prepared composite coating was reduced from 10.3 nm to 3.19 nm, and the corrosion current decreased by nearly three orders of magnitude. After the coating was soaked in 3.5 wt% NaCl solution for 30 days, the impedance modulus of the composite coating remained above 2.511 × 10 9  Ω cm 2 , reflecting that the introduction of the composite could effectively improve the anticorrosion property of the epoxy resin.