华北油田油井腐蚀结垢原因分析与治理方法优选

Cause Analysis of Corrosion and Scaling and Optimization of Preventive Method for Oil Wells in Huabei Oilfield

油田进入高含水开发期,抽油杆、油管腐蚀结垢问题日益严重,影响油田的正常生产。分析了腐蚀结垢的原因,对油井腐蚀结垢治理方法进行了优选。采出水矿化度高是腐蚀结垢的共性原因,主要腐蚀因素包括Cl-、CO_2、H_2S、SRB(硫酸盐还原菌)等,主要结垢因素是钙镁盐及铁腐蚀产物的沉淀。化学加药抑制腐蚀结垢是相对经济有效的治理方式,咪唑啉类表面活性剂对抑制Cl-、CO_2、H2S腐蚀有良好效果,有机膦酸通过鳌合成垢金属离子,起到阻垢作用。通过室内试验筛选配方,缓蚀率≥75%,阻垢率≥85%。现场采用井口加药的方式,在65口油井进行了5年的连续试验,有效遏制了腐蚀结垢,油井检泵周期延长2~3倍,取得良好经济效益。

In the high water-cut period of oilfield development,serious corrosion and scaling are induced in pumping rods and tubings day by day,which would effect the normal production in the oilfield.The reasons of corrosion and scaling are analyzed,the methods for their prevention are optimized.The high salinity in oilfield produced water is the common factor of corrosion and scaling,the main corrosion factor includes Cl^-,CO_2,H_2S,SRB,etc.The main scaling factor included calcium magnesium salt and precipitation of iron corrosion products.It is relatively economical and effective governance to inhibit corrosion and scaling by chemical way,the imidazoline surfactant is effective to inhibit the Cl^-,CO_2,H2S corrosion,the organic phosphonic acid is effective to inhibit scaling through chelating scale of metal ions.Formulae are screened through laboratory test,the corrosion inhibition rate is≥75%,the scale inhibition rate is≥85%.By using the method of dosage in wellhead,5years of continuous testing has been carried out in 65 wells,scaling is effectively prevented,the pump detection period is prolonged by 2-3times,good economic benefit is obtained.