镇原油田含硫区套损机理研究与防腐工艺应用

Study on Main Causes of Casing Corrosion in Hydrogen Sulfide Bearing Block of Zhenyuan Oilfield

为解决镇原油田含硫化氢区块新增套破趋势凸显的现状,通过高温高压釜试验,模拟J55套管在腐蚀工况环境中的腐蚀行为,明确了其在CO_(2)=1 MPa,CO_(2)=1 MPa、H_(2)S=0.6 MPa环境中的腐蚀速率分别为0.2117,0.1133 mm/a。通过扫描电子显微镜、X射线衍射等分析手段明确了模拟试验的腐蚀产物及现场所取的腐蚀产物均主要为FeS、FeCO_(3),二者基本一致,说明CO_(2)及H_(2)S是套管腐蚀的主要因素,并且在CO_(2)+H_(2)S环境中,腐蚀由H_(2)S主导。同时利用目前在用除硫剂、缓蚀剂进行复配,优选出适应的抗硫缓蚀剂。现场投加井缓蚀率达到80.2%。耐温阳极成分及电化学性能优选,选取电流效率高于45.0%的阳极,通过将阳极触壁改进优化,可有效降低套管腐蚀速率。结果表明,通过抗硫缓蚀剂及耐温阳极配套可有效降低套管腐蚀速率。

In order to solve the current situation of prominent new casing failure trend of hydrogen sulfide block in Zhenyuan Oilfield,the corrosion behavior of J55 casing in corrosive working environment was simulated through high-temperature autoclave test,and the corrosion rate of J55 casing in CO_(2)=1 MPa,CO_(2)=1 MPa and H_(2)S=0.6 MPa was determined to be 0.2117,0.1133 mm/a respectively.Scanning electron microscopy,X-ray diffraction and other analytical means have confirmed that the corrosion products in the simulation test and the corrosion products taken in the field are mainly FeS and FeCO_(3),which are basically the same,indicating that CO_(2) and H_(2)S are the main factors for casing corrosion,and H_(2)S is the dominant corrosion in the CO_(2)+H_(2)S environment.At the same time,by using the combination of sulfur remover and corrosion inhibitor currently in use,the suitable sulfur-resistant corrosion inhibitor was optimized.The corrosion inhibition rate reached 80.2%when the well was added in the field.The composition and electrochemical performance of the temperature resistant anode were optimized.The results show that the corrosion rate of casing can be effectively reduced by the combination of sulfur resistant corrosion inhibitor and temperature resistant anode.