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Drilling engineering, drilling corrosion is a common problem when different stratigraphic drilling, drilling fluid pH value, temperature, salinity, dissolved gas type and content changes, corrosion type and speed of the drill will change, for different conditions of the drilling fluid to develop a corrosion inhibitor has an important significance. The G105 steel corrosion in different temperature simulation of drilling fluid (natural seawater, acidic seawater and high density brine), studied by static weight loss method investigated by nonylphenol polyoxyethylene ether phosphate composite corrosion The inhibition effect of the agent; investigated by dynamic weightlessness Compound Inhibitor in to 70 ℃ dynamic simulation of drilling fluid in the inhibition effect; using polarization curves, electrochemical impedance spectroscopy and surface morphology observation studies composite slow the inhibition mechanism of corrosion agent; using electrochemical impedance spectroscopy to evaluate the corrosion film lasting and corrosion resistance. Weightlessness experimental results show that the three simulations drilling fluid corrosive order: high density brine gt; the acidic seawater gt; natural seawater; the composite inhibitor can effectively inhibit the G105 steel corrosion in three simulated drilling fluid, high temperature inhibition effect than inhibition effect of low temperature, 70 ° C. 70 ° C, 90 ° C natural seawater when the inhibitor concentration of 150 mg / L, the inhibition rate was 98.1%, 95.2%; 70 ℃, 90 ℃ acidic seawater and high density brine, the best corrosion concentration than natural seawater in large quantities, but equal to or less than 300 mg / L, corresponding inhibition rate reached more than 75%. In of 70 ℃ dynamic natural seawater, acidic seawater and high density brine, the corrosion rate of 98.5%, 86.8% and 91.7%, respectively. The polarization curves show that the composite 70 ° C in natural seawater corrosion inhibitors showed an anodic inhibitor, change the electrode reaction process; acidic sea water of different temperatures, corrosion inhibitors, the same performance as an anodic inhibitor; 70 ° C high density brine, corrosion inhibitor is to control the anode reaction-based mixed-type inhibitor. Impedance spectra characteristic mechanism of action of the inhibitor in natural seawater can be divided into different stages: the the inhibitor film growth process, dense corrosion inhibitor film subsisting process, membrane decay process. Dense corrosion film can last at least to 120 h. Compound Inhibitor formed in low-temperature acidic seawater corrosion film is slow, need to 48h at 25 ° C to form the main structure of the corrosion film, at 50 ° C, 70 ° C, just 2h on form. Inhibition membranes in acidic seawater each temperature at least for 144 h to protect the base body is not corroded. Compound Inhibitor 70 ° C high density brine dense corrosion film formed at 48 h and 48 h after the corrosion film is damaged. Saline and acidic waters and high density compared to natural seawater is more conducive to the composite corrosion inhibitor into dense corrosion film on the electrode surface line, composite corrosion inhibitor in natural seawater corrosion inhibiting effect is also better than in the other two solutions in. Corrosion film in the drilling fluid without inhibitor analog corrosion resistance are poor, vulnerable to destruction, should be promptly added corrosion inhibitor. The surface morphology observed results show that the compound inhibitors can inhibit G105 steel in natural seawater and acidic seawater pitting, cracks like corrosion, corrosion inhibitor involved in the surface of the film-forming reaction.
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