针对油田侏罗系油井的内腐蚀套损问题,以重点腐蚀段长效防护为目标,研制了耐温阳极套管内防腐蚀技术。依据阴极保护相关规范,在室内搭建4组模拟试验,开展720 h套管极化性能测试,探究套管内涂层、介质溶液、温度对牺牲阳极保护效果的影响,验证理论计算和数值计算结果。结果表明:油管不影响工具对套管的保护;阳极 数量增加对保护电位分布和输出电流无影响;阳极间距增加,保护电位衰减较快,当阳极中点的保护电位达到-0.8 V 时,该间距为最大有效保护距离;牺牲阳极尺寸增加,有效保护距离变化不明显;在油田环境中,阳极寿命为2~4 a。通过现场性能优化、结构改进累计实施402口井,腐蚀速率由0.38 mm/a降低至0.19 mm/a,有效期在720 d以上。

Aiming at the problem of internal corrosion casing damage in Jurassic oil wells in oil fields, a temperature-resistant anode casing internal corrosion protection technology was developed with the goal of long-term protection of key corrosion sections. According to the relevant specifications of cathodic protection, four sets of simulation tests were built indoors to carry out 720 h casing polarization performance test. The effects of casing coating, medium solution and temperature on the protection effect of sacrificial anode were investigated, and the theoretical calculation and numerical calculation results were verified. The results showed that the tubing did not affect the protection of the casing by the tool. The increase of anode number had no effect on the protection potential distribution and output current. With the increase of anode spacing, protection potential decayed faster. When protection potential of anode midpoint reached -0.8 V, the distance was maximum effective protection distance. With the increase of sacrificial anode size, the effective protection distance did not change significantly. In the oilfield environment, the anode life was about 2-4 a. Through field performance optimization and structural improvement, 402 wells were implemented in total. The corrosion rate was reduced from 0.38 mm/a to 0.19 mm/a, and the validity period was more than 720 days.