Corrosion Behaviors of P110 Steel and Chromium Coating in CO_2-saturated Simulated Oilfield Brine

The protective chromium coating was prepared on P110 steel by employing pack cementation.The corrosion behaviors of P110 steel and the obtained coating in CO2-saturated simulated oilfield brine were studied by static complete immersion tests and electrochemical measurements.The corrosion attacks of the samples were determined by mass loss,corroded surface morphologies,corrosion products,and results of electrochemical measurements.The experimental results showed that the coating was uniform,continuous and compact.The chromium coating was slightly corroded,and the mass loss and corrosion rate of the coating were far lower than those of P110 steel.Chromium coating has higher self-corroding potential and lower corrosion current density than P110 steel in accordance with the electrochemical tests results.Taken as a whole,chromizing treatment has significantly improved the corrosion resistance of P110 steel.

Application of Artificial Neural Network in Predicting the Thickness of Chromizing Coatings on P110 Steel

A series of rare earth （RE） dispersed chromizing coatings were produced on P 110 steel by pack cementation. The orthogonal array design （OAD）was applied to set the experiments. An artificial neural network （ANN） approach is employed to predict the thickness values of the obtained chromizing coatings based on the OAD tests results. The results revealed that the built model was reliable, the thickness values of chromizing coatings were well predicted at selected process parameters, and the predicted error lied in rational range.

Wear and Corrosion Resistance of Electroless Plating Ni-P Coating on P110 Steel

In order to improve the surface performance and increase the lifetime of P 110 oil casing tube steel during operation, electroless plating was conducted to form Ni-P coating onto its surface. The surface morphology/element distribution and phase constitution of the Ni-P coating were analyzed using scanning electron microscope （SEM） equipped with energy dispersive spectrometry （EDS） and X-ray diffraction （XRD）. Tribological and electrochemical measurement tests were applied to investigate the wear and corrosion resistance of P110 steel and the Ni-P coating. The results showed that a uniform and compact, high phosphorous Ni-P coating was formed. The obtained Ni-P coating indicated certain friction-reduction effect and lower mass loss during friction-wear tests. The Ni-P coating also exhibited higher corrosion resistance in comparison with bared P 110 steel. The obtained N i-P coating has significantly improved the surface performance of P110 steel.

人工神经网络方法预测P110油套管钢稀土渗铬层的厚度

利用人工神经网络原理,建立了反映P110油套管钢(P110钢)稀土渗铬工艺参数与渗铬层厚度关系的预测模型。结果显示:该模型可以对选定工艺条件下渗铬层厚度进行良好的预测,预测结果在合理的误差范围内,建立的模型是可靠的,可以通过此模型优化工艺参数,实现P110钢稀土渗铬层厚度预测。

20钢和P110钢CO_2腐蚀静态及动态缓蚀性能研究

借助高温高压腐蚀反应釜,测试了咪唑啉和有机胺类缓蚀剂在饱和CO2油田采出液对20和P110钢的静态和动态缓蚀行为,并对表面腐蚀形貌进行分析。结果表明:20钢静态电化学行为呈现活性溶解而P110钢发生钝化,缓蚀剂加入后均降低了腐蚀电流。缓蚀剂浓度是影响20和P110钢动态缓蚀行为的显著因素,材料表面均匀致密的产物膜层直接影响其缓蚀效果。

基于多因素共存条件下P 110钢的电化学行为

油井管在服役过程中会同时受到力学因素、环境因素和介质因素的影响。以P 110钢为例,为探究多因素共存条件对P 110钢CO 2腐蚀的影响,采用正交试验方法同时结合电化学测试手段研究了在饱和CO 2环境中基于“压应力—温度—NaCl”共存条件下P 110钢的电化学行为。结果表明:在“压应力—温度—NaCl”共存条件下,温度对P 110钢电化学行为的影响最为显著,随着温度的增加P 110钢CO 2腐蚀过程的电化学反应速率不断增大;NaCl和压应力对P 110钢电化学行为的影响远不及温度对其的影响,但二者的影响程度较为接近,随着NaCl含量的增加,P 110钢CO 2腐蚀过程的电化学反应速率先增大后减小,拐点处的临界NaCl含量为3.5%。随着压应力的增加P 110钢CO 2腐蚀过程的电化学反应速率同样呈现先增大后减小的规律,拐点处的临界压应力为90%σs。因此,应多关注服役于“压应力—温度—NaCl”共存条件下的P 110钢在高温下CO 2腐蚀带来的失效风险。

Effect of Ca2+ and Mg2+ on CO2 Corrosion Behavior of Tube Steel

Effects of Ca2+ and Mg2+ on the CO2 corrosion behaviors of tube steel were studied in simulated oil-field environment.The influence of Ca2+and Mg2+ on the corrosion rate and morphologies of corrosion product layer was determined by scanning electron microscope and measuring mass loss.Potentiodynamic polarization and impedance spectroscopy were used to investigate the change of electrochemical characteristic parameters of corrosion product layer and corrosion dynamic process.The results show that with Ca2+ and Mg2+ in electrolyte,the morphologies and microstructures of corrosion product layer changed obviously,thus affecting the corrosion process.

Influence of adding various rare earths on microstructures and corrosion resistance of chromizing coatings prepared via pack cementation on P110 steel

In order to improve the corrosion resistance and increase the service lifetime of P110 steel during operation,four chromizing coatings were formed onto its surface with/without addition of rare earths via pack cementation process.The surface morphologies and microstructures of the chromizing coatings were observed using scanning electron microscopy(SEM),and the phase constitutions were investigated by X-ray diffraction(XRD).Electrochemical corrosion behavior of the chromizing coatings in simulated oilfield ...

Influence of process parameters on thickness and wear resistance of rare earth modified chromium coatings on P110 steel synthesized by pack cementation

The pack cementation was employed to produce rare earth modified chromium coatings on P110 steel aiming at improving its performance and increasing the usage lifetime during operation. The orthogonal array design （OAD） was applied to set experiments. Contents of NH4Cl, types of RE, contents of RE, test temperature and soaking time were the main factors, and each factor was endowed with four levels. While the range analysis and analysis of variance were used to investigate the results of OAD tests on thickness and wear resistance. The results indicated that for a promising coating with higher thickness value and excellent anti-wear property, the test temperature was the most significant process factor. The potential promising conditions for chromizing treatment were： adding 1% NH4Cl and 1% LaCl3, maintaining the test temperature at 1000 oC for 8 h. The results of verification showed that the coating formed under the optimal process parameter had a valid thickness of 28 μm and a reduction of 0.32 mg in wear resistance test.

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 massqoss 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 cor- rosion 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 bv electrochemical test and mass-loss experiment.

环空环境下P110油管钢的电化学腐蚀行为

通过模拟典型CO2驱注井环空环境,采用电化学测试、浸泡实验和腐蚀特征的扫描电镜(SEM)观察,研究了P110钢在CO2驱注井环空环境中的电化学腐蚀行为。结果表明,随着溶液pH值和H2S分压的增大,极化电阻值逐渐提高,P110钢的腐蚀电流密度不断下降,其耐蚀性增加;溶液中加入H2S抑制了P110钢基体表面的阳极反应,降低了均匀腐蚀电流密度,但是阴极充氢作用得到加强,促进了裂纹的萌生,应力腐蚀敏感性增大。

一种新型Mannich碱酸化缓蚀剂的合成及性能评价

根据Mannich反应原理,以肉桂醛、苯乙酮和伯胺为原料合成了一种新型的Mannich碱酸化缓蚀剂。借助红外光谱对合成产物结构进行了表征,并采用电化学法和静态失重法对该缓蚀剂进行了缓蚀性能评价。电化学阻抗谱和极化曲线结果说明该缓蚀剂是一种混合型缓蚀剂,可在P110钢试片表面形成明显的保护性膜,其作用机理符合"几何覆盖效应"。静态失重法结果表明,这种缓蚀剂对P110钢在盐酸溶液中的腐蚀具有明显的抑制能力,可以满足石油行业标准SY/T5405-1996缓蚀剂一级产品的指标要求;试片的腐蚀速率随着盐酸浓度和溶液温度的升高逐渐增大,随着缓蚀剂浓度的增加而减小。缓蚀剂浓度与缓蚀效率的关系进一步阐明该缓蚀剂在P110钢试片表面的吸附作用符合Langmuir单分子等温吸附规律。