延长油田典型油井采出水对N80钢的腐蚀及缓蚀剂研究

发布时间：2018-03-16 07:35

本文选题：油井采出水　切入点：N80钢　出处：《西南石油大学》2017年硕士论文　论文类型：学位论文

【摘要】：油管腐蚀己成为制约油气田发展的一个重大问题,其中油井采出水对油管的腐蚀备受关注。因各油田的采出水组成以及腐蚀环境的差异,使得相应的腐蚀研究具有针对性。延长油田某采油厂发现油管腐蚀问题,腐蚀严重的油井处于开发后期,含水率高达90%左右,有必要研究采出水的腐蚀性及相应的防腐措施。以腐蚀严重的4种油井采出水作为研究对象,首先进行水质分析;然后运用失重实验讨论温度、溶解氧及腐蚀介质流速对N80钢腐蚀的影响,并对腐蚀产物进行能谱分析;采用电化学方法研究温度、溶解氧、浸泡时间以及锈层对N80钢腐蚀行为的影响;测试咪唑啉季铵盐DN5-4、咪唑啉酰胺DTC以及脂肪酸咪唑啉CI-2的溶解性和稳定性,并研究它们在4种采出水中的缓蚀性;在1号和3号采出水中确定了最佳缓蚀剂浓度、考察了缓蚀剂的阳极脱附行为以及后效性;在2号和4号采出水中将乌洛托品、硫脲、抗坏血酸、平平加O、十二烷基苯磺酸钠等分别与CI-2复配,研究其缓蚀协同作用;对具有协同效应的复配体系进一步讨论复配比例、阳极脱附以及后效性等问题;最后采用动态失重实验测试所选缓蚀剂的作用效果。研究结果表明:溶解氧和流速对N80钢腐蚀的影响较大,温度次之,腐蚀产物主要是铁的氧化物和FeC03;升高温度未改变腐蚀机理,仅加快了腐蚀反应;氧参与了腐蚀反应,低频时氧浓差扩散是反应的控制步骤;浸泡17 d后,1、3、4号采出水中的阻抗值变化较小,腐蚀产物膜稳定,2号采出水中的阻抗值一直较高,腐蚀程度较浅;生锈试样对靠近它的未锈试样有腐蚀加速作用,温度越高加速作用越大;1号和3号采出水中CI-2的缓蚀性好,抑制阳极反应,最佳浓度为1000 ppm,动态失重实验下的缓蚀率总体高于90%;CI-2在1号采出水中,过电位高于0.52 V时出现轻微的阳极脱附,在3号采出水中没有发生阳极脱附,且在两种介质中后效性好;2号采出水中,CI-2与平平加O按1:1复配时有缓蚀协同作用,协同系数为1.26,最佳复配比例是3:1,过电位高于0.37V后出现轻微的阳极脱附,浸泡8d后仍具有较好的缓蚀性,失重实验测得的缓蚀率(除0.8 m/s外)介于92%～98%;4号采出水中,CI-2分别与硫脲、乌洛托品、抗坏血酸1:1复配时有缓蚀协同作用,协同系数分别为2.24、4.97、1.53,最佳复配比例均为4:1;4号采出水中,CI-2与抗坏血酸复配后,当过电位高于0.36 V后部分缓蚀剂出现阳极脱附,与硫脲复配后未出现阳极脱附现象,与乌洛托品复配后,当过电位高于0.5 V后发生严重的阳极脱附;CI-2与硫脲或乌洛托品4:1复配,浸泡8 d后的阻抗值仍然很高,后效性好,CI-2与抗坏血酸复配后,当浸泡7 d后,容抗弧变得很小;4号采出水中3种复配方式均能得到普遍高于90%的缓蚀率,但CI-2与硫脲和乌洛托品复配后,发生了严重的局部腐蚀,而CI-2与抗坏血酸复配后表现为均匀腐蚀,故4号采出水中采用CI-2与抗坏血酸以4:1复配。
[Abstract]:The corrosion of tubing has become a major problem restricting the development of oil and gas fields, in which the corrosion of produced water from oil wells to tubing has attracted much attention. So that the corresponding corrosion research has pertinence. Yanchang oil production plant found tubing corrosion problem, the corroded oil well is in the late stage of development, the water cut is about 90%, It is necessary to study the corrosion of produced water and the corresponding anticorrosion measures. Taking four kinds of produced water from oil wells with serious corrosion as the research object, the water quality is analyzed first, and then the temperature is discussed by weightlessness experiment. The effects of dissolved oxygen and corrosion medium flow rate on the corrosion behavior of N80 steel were studied by energy dispersive analysis of corrosion products, and the effects of temperature, dissolved oxygen, immersion time and rust layer on corrosion behavior of N80 steel were studied by electrochemical method. The solubility and stability of imidazoline quaternary ammonium salt DN5-4, imidazolinamide DTC and fatty acid Imidazoline CI-2 were tested, and their corrosion inhibition in four kinds of extracted water were studied. The anodic desorption behavior and after-effect of corrosion inhibitor were investigated, and Ulotropine, thiourea, ascorbic acid, Pingping plus O, sodium 12 alkylbenzene sulfonate were mixed with CI-2 in the effluent of No. 2 and No. 4, respectively, to study the synergistic effect of the inhibition on corrosion of Ulotropine, thiourea, ascorbic acid, sodium 12 alkylbenzene sulfonate and so on. The proportion, anodic desorption and after-effect of the complex system with synergistic effect were discussed. Finally, the effect of corrosion inhibitor selected by dynamic weightlessness test was tested. The results showed that dissolved oxygen and flow rate had great influence on corrosion of N80 steel, followed by temperature. The corrosion products are mainly iron oxides and FeC03.The corrosion mechanism is not changed by increasing the temperature, only the corrosion reaction is accelerated, the oxygen is involved in the corrosion reaction, and the oxygen concentration diffusion is the control step of the reaction at low frequency. After 17 days of immersion, the impedance value of water extracted from No. 1 and No. 4 is small, the corrosion product film is stable, the impedance value of No. 2 recovery water is always higher, the corrosion degree is relatively shallow, and the corrosion rate of the rust specimen is accelerated to the unrusted sample near it. The higher the temperature, the greater the acceleration, the corrosion inhibition of CI-2 in No. 1 and No. 3 recovery water is good, the best concentration is 1 000 ppm, and the corrosion inhibition rate of dynamic weightlessness experiment is higher than that of 90% CI-2 in No. 1 recovery water. When the overpotential is higher than 0.52 V, there is slight anodic desorption, no anodic desorption occurs in No. 3 recovery water, and the aftereffects are good in two kinds of medium. The synergistic coefficient is 1.26, the optimum ratio is 3: 1, the anode desorption occurs slightly after overpotential is higher than 0.37 V, and the corrosion inhibition rate (except 0.8 m / s) measured by weightlessness experiment is between 92m/ s and 980.The corrosion inhibition rate measured by weightlessness experiment (except 0.8 m / s) is between 922% and 98%, and CI-2 and thiourea in water from No. 4 recovery water are respectively with thiourea. Ulotropine, ascorbic acid 1: 1 has the synergistic effect of corrosion inhibition, the synergistic coefficient is 2.2444.97 / 1.53 and the optimum ratio is 4: 1.4.The anodic desorption of partial corrosion inhibitor appears when the overpotential is higher than 0.36 V after the combination of CI-2 and ascorbic acid in the recovery water of No. 4. After mixed with thiourea, there was no anodic desorption phenomenon. After mixed with Ulotropine, serious anodic desorption CI-2 and thiourea or Ulotropine 4: 1 were found when the overpotential was higher than 0.5 V, and the impedance value was still very high after 8 days of immersion. After mixing with ascorbic acid for 7 days, the capacitive reactance arc became very small, and the corrosion inhibition rate was higher than 90% in the water of No. 4 recovery, but CI-2 was mixed with thiourea and Ulotropine. Serious local corrosion occurred, and the combination of CI-2 and ascorbic acid showed uniform corrosion. Therefore, CI-2 and ascorbic acid were used in No. 4 recovery water at 4: 1.
【学位授予单位】：西南石油大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TE983

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