大港油田采油装置腐蚀机理研究

The Research on Corrision Mechinism of Dagang Oil Field

大港油田油藏温度差异大,地层水性质变化大,南部油田腐蚀率高于中北部数倍,尽管采取了较多措施,但腐蚀率仍然较高,因此,需要对其进行研究并寻求相应的对策。采用差点法在9个联合站取样分析水中各种离子和微生物浓度,用静态和动态法研究了含有细菌和无细菌条件下的腐蚀速率、矿化度和硫酸盐还原菌(SRB)的浓度关系等。结果表明,南部油田地层水矿化度最高(35g/L),硫酸根含量为50-150mg/L,SRB数量虽然低于102cell/mL,但是腐蚀率高于标准值71%;中北部油田的情况却相反;在SRB存在的情况下,腐蚀率较无菌条件下高73%,产出水适宜微生物生长,水的pH和Eh都有不同的变化规律。由于南部的矿化度较高,腐蚀主要原因是电化学腐蚀,微生物腐蚀占有重要的比例。产物电镜分析表明,无菌和含菌条件下主要成分为Fe、S化合物和碳酸钙类。通过不同浓度SRB与腐蚀率的实验,获得了SRB对腐蚀的贡献率,提出了控制SRB数量指标,减少SRB数量和腐蚀的初步对策。

The oil temperature diversity is great, the character of ground waterchanges evidence in dagang oil field, the corrision rate is several times higher in south oil field than in middle and north part, although several measures has been taken, the corrision rate still keeps in high level.The research in it is necessary and looking for correspond countermeasure. Making use of the otherness to sampling and analyse the water quality, ion and microbiology concentration, with static and dynamic studing, under the conditions of the bacteria contained and no bacteria the corrosion rate, salinity and sulfate-reducing bacteria （SRB）and the concentration of relations has been explored. The experimental result indicated that, the south sub-area salinityis highest （35g/L）, the sulfate radicalion concentration is 50-150mg/L,although the number of SRB is no more than 10^-2 cell/mL, the corrision rate is 71% higher than standard; the situation in middle and north part oil field is just reverse, if the SRB is subsistent, the corrision rate is 73% higher than unsubsistent, the water was filled with the microbiology＇s growth, pH and Eh have the different rule.Because of the high salinity in south part ,the main reason of crrosion is electrochemistry, as well as the MIC. Product of electron microscopy analysis showed that the bacteria and sterile conditions for the main components Fe, S and calcium carbonate compounds category. SRB through different concentrations and the rate of corrosion, the SRB was the contribution rate of corrosion, the SRB made a number of indicators of control and reduce the number of SRB and corrosion of the preliminary measures.