昆特依区块环空保护液环境油套管柱的腐蚀行为研究

Study on the Corrosion Behavior of Oil Casing String in Annular Protection Fluid Environment of Kunteyi Block

为了明确高矿化度及高温环空保护液环境下油套管材料的腐蚀行为,利用高温高压测试系统评价了非应力和应力状态下的油套管材料在模拟油田环空保护液环境下的腐蚀损伤敏感性。通过扫描电子显微镜以及能谱仪对材料表面产物膜层的微观形貌、横截面的膜层特征以及产物膜化学组成进行分析表征。结果表明:材料在未经除氧处理的环空保护液中腐蚀相对较严重,腐蚀产物膜呈龟裂状且局部脱落,脱落处可见底层膜层开裂,其中P110材料的平均腐蚀速率最高达3.83 mm/a;横截面观察表面双膜层的开裂只限于腐蚀产物膜,未涉及基体材料,材料呈均匀腐蚀减薄;环空保护液经过除氧处理后侵蚀性明显降低,其中P110材料的腐蚀速率降低80%。在高温高压未除氧的环空保护液环境及加载应力协同作用下,P110和P110SS 2种材料的应力腐蚀开裂不敏感,腐蚀减薄是P110油套管材料的主要腐蚀损伤模式。

Aiming at clarifying the corrosion behavior of oil casing materials in high salinity and high temperature annulus protection fluid environment,the corrosion damage sensitivity of oil casing materials under non-stressed and stressed conditions in the simulated oilfield annulus protection fluid environment was evaluated by high temperature and high pressure(HPHT)test system.The micromorphology,cross section characteristics and chemical composition of the product film on the surface of the material were analyzed and characterized by scanning electron microscope and energy dispersive spectrometer.Results showed that the corrosion of the material was relatively worse in the annulus protection liquid without deoxygenation treatment.The corrosion product film was cracked and partially detached,and the cracking of the bottom film layer could be seen at the shedding place.Moreover,the average corrosion rate of P110 material was up to 3.83 mm/a.Observing the cross section could find the cracking on the surface of the double film layer was limited to the corrosion product film,and the substate material was not involved.The material was uniformly corroded and thinned.Furthermore,after deoxygenation treatment,the erosion of the annulus protection fluid decreased significantly,and the corrosion rate of P110 material decreased by 80%.Generally,P110 and P110SS were insensitive to stress corrosion cracking under the synergistic effect of high temperature and high pressure annulus protection fluid without deoxygenation treatment environment and loading stress,and corrosion thinning was the main corrosion damage mode of P110 oil casing material.