利用高效嗜油菌抑制油田采出水处理和回注系统腐蚀的机理研究

The corrosion of metal structures and pipeline is extremely serious in treatment and reinjection system of oilfield produced water. However, traditional anticorrosion method is costly or may produce secondary pollution problems. Our research team had found an oil-degrading bacterium named YY-3 which could inhibit the occurrence of corrosion, but its mechanism of anti- corrosion is not yet clear. This study proposes to carry out 4 aspects of researches: biocompetitive exclusion mechanism between YY-3 and SRB, relationship between corrosion inhibition and oxygen, the role of biofilm in corrosion inhibition and changes of corrosion products by metabolism of YY–3. The possible mechanisms of corrosion-inhibition will be examined and determined successively and electron transfer pathway will be inferred to give an explanation on the relation between degradation of crude oil, dissolved oxygen consumption, biofilm and corrosion behavior. This study is helpful to reveal the new corrosion-inhibition mechanism of an unknown oil-degrading strain. Meanwhile, it is useful for developing a green technique which could alleviate the extent of corrosion in treatment and reinjection system of oilfield produced water in practice.

油田采出水处理和回注过程中金属构筑物和管道腐蚀严重，传统防腐方法成本较高或者会产生次生环境问题。本课题组筛选出一株能显著抑制腐蚀的高效嗜油菌YY-3，但其抑制腐蚀的机理尚未清楚。本研究拟从YY-3与SRB的竞争驱除机制、腐蚀抑制与氧气的关系、生物膜在腐蚀抑制中的作用以及YY-3对腐蚀产物的改变四个方面入手，依次排除和推断YY-3在处理油田采出水时的腐蚀抑制机制，推测腐蚀防护过程中电子转移的途径，阐明原油降解、溶解氧消耗、生物膜以及腐蚀行为四者之间的耦合关系。这些研究有助于揭示未知嗜油菌在金属腐蚀抑制中起作用的机理和影响因素，并有助于发现新的微生物防腐机理。同时，在实践上也有利于缓解油田采出水处理及回注系统的金属腐蚀问题，提出一项新的绿色防腐技术。

在油田采出水处理和回注过程中，设备和管道腐蚀非常严重。现有的油田防腐技术存在成本费用过高或容易产生次生环境问题的不足，当前很有必要发展绿色的、环境友好且廉价的油田防腐技术。本项目从处理原油废水的污泥中筛选出4株可以抑制腐蚀的嗜油菌，从四方面分析高效嗜油菌抑制腐蚀的机理，1）好氧呼吸代谢过程：微生物降解有机物产生电子，溶解氧优先接受这些电子，阻断了Fe失去电子传递到氧气这一途径，从而降低了腐蚀速度。在微生物利用氧气代谢有机物的过程中，多糖的 O-H 键、蛋白质 C=O 键和氨基酸COO-参与了铁离子的结合过程，脂肪类C-H官能团未参与Fe离子结合过程；2）生物膜保护层的形成：生物膜对钢片和培养基以及氧气的隔离效应可以很大程度上减缓腐蚀。细菌的成膜能力越强，生物膜越厚越密集，对钢片与外界的物质传递的机械阻断作用越明显，阻碍阳极过程进行，使金属的溶解速度大大降低。接种细菌可形成良好的保护作用，使得碳钢表面晶格常数、晶面间距和晶胞体积未发生明显变化；3）与SRB的竞争：在本研究中微生物防腐的机制不是通过生物驱除策略抑制腐蚀；4）腐蚀产物的改变：在采出水中N80钢的腐蚀产物主要成分是FeCO3，可逐渐溶解在培养液中，接菌的钢片腐蚀产物是铁氧化物，形成了一层钝化膜阻止了Fe的溶解。