Simulated Oilfield Environment Research Articles

Transition from Pits to Stress Corrosion Cracking of SAE 4120 Steel in Simulated Oilfield Environment

Transition from Pits to Stress Corrosion Cracking of SAE 4120 Steel in Simulated Oilfield Environment

Influence of H2S on the pitting corrosion of 316L stainless steel in oilfield brine

Coupon immersion tests were performed on 316L stainless steel in a simulated oilfield environment to evaluate the effect of H2S partial pressure on pit depth and density. Pitting was most significant at intermediate partial pressures of H2S, for which free H2S in the pit solution is maximised. Inhibition of pitting at higher partial pressures is attributed to blocking of the pit surface by metal sulphide phases. The key role of pH in the pit solution is to determine the solubility of metal sulphides and the availability of free H2S to adsorb on the reacting pit surface and sustain activity.

Effect of CO2/H2S and Applied Stress on Corrosion Behavior of 15Cr Tubing in Oil Field Environment

The corrosion behavior of a 15Cr-6Ni-2Mo martensitic stainless steel (15Cr stainless steel) in a CO2/H2S environment was investigated by conducting high-temperature/high-pressure immersion tests combined with scanning electron microscopy and metallographic microscopy. The presence of H2S decreased the corrosion resistance of the 15Cr tubing steel. The critical H2S partial pressure (PH2S) for stress corrosion cracking in the 15Cr tubing steel in the simulated oil field environment with a CO2 partial pressure of 4 MPa and an applied stress of 80% σs was identified. The 15Cr tubing steel mainly suffered uniform corrosion with no pitting and cracking when the PH2S was below 0.5 MPa. When the PH2S increased to 1 MPa and the test temperature was 150 °C, the pitting and cracking sensitivity increased. The stress corrosion cracking at a higher PH2S is attributed to the sulfide-induced brittle fracture.

CO2 corrosion behavior of 1% Cr–13% Cr steel in relation to Cr content changes

The corrosion behavior of 1% Cr, 3% Cr, 4% Cr, 5% Cr, 6.5% Cr, 10% Cr and 13% Cr steel samples were investigated in a simulated oil field environment (60 °C, 2 m s−1, 2 MPa CO2). Weight loss tests were conducted in a high-temperature and high-pressure autoclave for 120 h. Scanning electron microscopy and energy dispersive spectroscopy were used to study the morphology and composition of corrosion scales. Polarization curves of the aforementioned seven steel samples were studied as well. The results showed that the average corrosion rates decreased with increasing Cr content in the steel substrate. The 1% Cr steel sample underwent mesa corrosion, and 10% Cr and 13% Cr steel showed very low corrosion rates owing to passivation. In the cases of 3% Cr–6.5% Cr steel, the Cr content was inadequate for passivation, but these samples showed low corrosion rates owing to the protective effects of corrosion scales.

The Anticorrosive and Antifouling Properties of Ni-W-P-nSiO2 Composite Coating in A Simulated Oilfield Environment

Aiming at the problem of tubing corrosion and scaling in the oilfield environment, the corrosion and scaling behaviour of nickel-tungsten-phosphorus-silica (Ni-W-P-nSiO2) composite coatings prepared on L245 is investigated by immersion test, electrochemical measurement and static scaling test. The results indicated that the corrosion rate of Ni-W-P coating (0.1075 mm a−1) was higher than that of Ni-W-P-nSiO2 coating (0.0552 mm a−1), consistent with the results of corrosion current density (icorr). It was also found that the compact corrosion product film that forms on the Ni-W-P-nSiO2 coating consists of Ni3S2 and FeO. The average scaling rate and calcium loss rate value of the Ni-W-P-nSiO2 coating (2.43 × 10−6 g cm−2 h−1, 0.0344−2 cm−2) were both lower than those of the Ni-W-P coating (1.53 × 10−5 g cm−2 h−1, 0.0542 cm−2), which indicates that SiO2 nanoparticle co-deposition in Ni-W-P coating with the contact angle of 93.71° can improve its antifouling property.

Effect of Flow Rate on the Corrosion Behavior of N80 Steel in Simulated Oil Field Environment Containing CO2 and HAc

Effect of Flow Rate on the Corrosion Behavior of N80 Steel in Simulated Oil Field Environment Containing CO2 and HAc

Role of HCO3- and Cl- in the Pitting of 20CrMo Steel in simulated oil field environment

Role of HCO3- and Cl- in the Pitting of 20CrMo Steel in simulated oil field environment

Corrosion Behaviors of 25CrMnVA Steel in CO<sub>2</sub> Flooding Enhanced Oil Recovery System

Influences of temperature and CO2 partial pressure on CO2 corrosion behaviors of 25CrMnVA steel were investigated in the simulated oil field environments. The corrosion rates were measured under high temperature and high pressure condition. SEM, EDS and XRD were used to analyze the morphologies and characteristics of corrosion scales on the steels. The results shows that the corrosion rates of 25CrMnVA steel change little below 65°C, the corrosion feature is uniform corrosion. The corrosion rates increase rapidly after 65°C, mesa corrosion is found on the surface of steel. The corrosion rates decrease firstly and increase subsequently with the rising of CO2 partial pressure, and the minimal corrosion rate presents near CO2 critical pressure. The compactness of corrosion scale improves with the increase of CO2 partial pressure below 8MPa, which causes uniform corrosion rate reduced. Under supercritical CO2 condition, the local defects in the surface of corrosion scale increase, and the compactness of corrosion scale reduces,which cause the increase of corrosion rate sharply. The corrosion rate and corrosion morphology are closely related to the state of corrosion scale.

Corrosion rate of hydrogenation to C110 casing in high H2S environment

The corrosion behavior of C110 bushing at high temperature and high pressure with a high H2S/CO2 was studied, and a basis for the materials selection of sour gas well bushing was provided in H2S, CO2 and saline coexisting environment. Under acidic condiction, hydrogen atoms greatly entered into the material and caused the material properties changed. Weight loss method was used to study the corrosion rate of hydrogen charging samples and original untreated samples in simulated oil field environment. PAR2273 electrochemical workstation was used to examine the electrochemical performance of samples untreated, hydrogen charging after reacting in autoclave. The corrosion product film was observed through SEM. The experimental results show that sample with hydrogen charging has a much more obvious partial corrosion and pitting corrosion than the untreated blank sample even the downhole corrosion speed of bushing is increased after being used for a period of time. Polarization curve shows the corrosion tendency is the same between sample with or without hydrogen charging and corrosion tendency is reduced by corrosion product film. A layer of dense product film formed on the surface of samples provides a certain protective effect to the matrix, but cracked holes which will accelerate partial corrosion of the sample were also observed.

Corrosion Resistance of E-Glass Fiber in Simulated Oilfield Environment

Corrosion behavior and mechanism of E-glass fiber in simulated oilfield environment including CO2, H2S and Cl- were firstly studied. After simulated corrosion test, morphology of E-glass fiber was gathered using SEM. Chemical bonding status and elemental analysis were systematically investigated by XPS, FT-IR and EDS. The results revealed that corrosion of E-glass fiber in simulated oilfield acidic medium was primarily attributed to ion exchange mechanism, which was not only controlled by acid concentration, but also dominated by formation of complex ions or insoluble salts. The depletion of cations on E-glass fiber surface can disrupt the continuity of glass network, therefore reducing the strength of fiber.

Corrosion behavior of low-nickel alloy steels in a simulated oilfield environment containing carbon dioxide

The microstructures and mechanical properties (tension strength Rm, yield strength Rt0.5 and impact energy Akv) of the low-nickel alloy steels 08Ni, 12CrNi and 20CrNi with and without heat treatment were measured and analyzed, as well as the common gathering pipeline steels (X60 and 16Mn). The results indicate that the mechanical properties of the low-nickel alloy steels with heat treatment are superior compared with other test materials, in the sequence as follows: (20CrNi) > (12CrNi) > (08Ni) > 20CrNi > 12CrNi > X60 > 08Ni > 16Mn (“(steel)” indicates the material with heat treatment, and “steel” means without). The weight-loss method was used to test the corrosion rates of the test materials exposed to a simulated oilfield environment for 168 h at 90 °C with the CO2 partial pressure and total pressure 2 MPa and 10 MPa, respectively. The systematical characterization with scanning electron microscope and X-ray diffraction displayed the different micro-morphology of corrosion scales formed on the surface of the test materials with FeCO3 as the only detected composition of corrosion product. That the low-nickel alloy steels with heat treatment showed a higher corrosion resistance than those without, mainly resulted from the different microstructures of the matrix, the characteristics of corrosion scale and the composition of elements.

Corrosion resistance of E6-glass fibre in simulated oilfield environments

In order to understand the corrosion behaviour of E6-glass fibres in oilfield environments, three different oilfield atmospheres were first given. Morphologies and chemical bonding status of the corroded fibres were investigated by scanning electron microscopy, X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. The results reveal that corrosion of E6-glass fibres in simulated oilfield acidic media can be primarily attributed to the ion exchange mechanism, which is not only controlled by acid concentration, but is also dominated by the formation of complex ions or insoluble salts. The depletion of cations on E6-glass fibre surface can disrupt the continuity of the glass network, thus disturbing the glass structure and therefore reducing the strength of fibres.

Corrosion of E-glass fiber in simulated oilfield environments

In order to have a better understanding of corrosion behaviors and mechanisms of E-glass fibers in oilfield environments, three different oilfield atmospheres including CO 2, H 2S and Cl − were firstly given. After different simulated corrosion tests, morphologies of E-glass fibers were gathered using SEM. Chemical bonding status and elemental analysis were systematically investigated by XPS, FT-IR and EDS. The results revealed that corrosion of E-glass fibers in simulated oilfield acidic media was primarily attributed to ion exchange mechanism, which was not only controlled by acid concentration, but also dominated by formation of complex ions or insoluble salts. The depletion of cations on E-glass fiber surface can disrupt the continuity of glass network, thus disturb the glass structure, therefore reducing the strength of fibers.

Formation Characteristic of CO 2 Corrosion Product Layer of P110 Steel Investigated by SEM and Electrochemical Techniques

Formation characteristic of CO2 corrosion product layer on the surface of P110 steel was investigated in simulated oilfield environment using mass-loss experiment, potentiodynamic polarization curve, impedance spectroscopy, and SEM micrograph analysis. Samples of different times up to 240 h were tested during exposure. Corrosion product was primarily composed of Fe(Ca, Mg)(CO3)2, which was distinguished by two layers. With an increase in the exposure time, the charge transfer resistance and polarization resistance increased progressively, the uniform corrosion rate decreased, and the corrosion reaction was controlled by the diffusion process instead of the activation process. All phenomena were attributed to the formation of the protective corrosion product layer. More compact and lower porosity of the layer made it more difficult to transfer and diffuse through the corrosion product layer for the charges and ions. Similar results were obtained by electrochemical test and mass-loss experiment.