绥中36-1油田油管腐蚀产物及土酸酸蚀特征研究

A Study of the Corrosion Product and Its Mechanism of Suizhong 36-1 Oilfield Well Tubes

用扫描电镜、能谱分析和X-射线衍射仪等测试方法,对比分析了绥中36-1油田典型井J13井油管土酸处理前后的腐蚀结垢产物。结果表明,土酸处理前的腐蚀结垢产物主要元素为Fe、O、S、C,次要元素为Ca、Mg、Si,X-射线衍射分析矿物为黄铁矿、含镁方解石、菱铁矿,电镜下观察腐蚀产物中广泛存在着海绵状及珊瑚状硫化物。土酸常温浸泡腐蚀产物2 h后,酸蚀率为13.1%,垢样表层基本不含Ca、Mg等元素,富含Fe、O、S等元素,其矿物成分为Fe(OH)3、Fe2O3、FeS等,晶形完好的莓状氧化铁及氢氧化铁小球经酸化后被部分溶蚀,酸处理后的残余物主要为非晶质或隐晶质。腐蚀机理为:SRB将硫酸根离子作为有机物代谢产物的最终电子受体,少量的被还原成硫,大部分以硫化氢(H2S)形式放出,在其代谢过程中对油井油管造成腐蚀。

The corrosion product of J13 well tubes was analyzed by XRD,EDS and ESEM.The main elements of the scale before mud acid treatment were Fe、O、S、C,and semi-elements were Ca、Mg、Si.The results of X-ray diffraction showed that the main contents of mineral were pyrite,magnesium calcite and siderite.SEM test showed that sulfide shapes like cavernous or coralliform widely existed in the corrosion products.The etching rate was of 13.1% after 2hrs acid treatment.The surface of acidification products didn＇t contain Ca、Mg,but were rich of Fe、O、S,which should be Fe（OH）3、Fe2O3、FeS.The globule of well crystalline iron oxide and ferric hydroxide were partly dissolved during acidification,thus the residue were mainly amorphous or cryptocrystalline.The mechanism of corrosion was that SRB were anaerobic bacteria which took sulfate ions as the final electron acceptor of organic metabolites,transferred a small amount of them to sulfur,and released most of them in form of hydrogen sulfide（H2S）.In the course of metabolism,SRB caused the corrosion of oilfield well tubes.