哈6区块腐蚀结垢分析及对策研究

Analysis and Countermeasures of Corrosion and Scaling in the Ha6 Block

哈6区块存在CO_2和H_2S含量高,地层水矿化度高、Cl^-含量高等腐蚀结垢恶劣条件,极易发生腐蚀结垢、影响油井正常生产。区块主要在CO_2/H_2S共存条件下造成腐蚀,其主要影响因素为p_(CO_2)/p_(H_2S)值,地层水中成垢离子受温度、压力降低导致溶解度降低而结垢,酸化措施是由于缓蚀剂被岩层矿物吸附,导致残酸返排时对管柱造成腐蚀结垢,注气替油措施是因为溶解氧的存在造成管柱腐蚀结垢。从部位、缝洞带、生产管柱、产出液含水、酸化措施共5个方面分析了腐蚀结垢现状,结果显示整体表现较轻微,但不容忽视。目前油管、套管使用以抗硫管柱为主,地面设备及管道防腐采用深井阳极强制电流阴极保护方法。在前人研究基础上,针对性地提出了根据p_(CO_2)/p_(H_2S)值确定使用油管材质、酸化顶替液改进、注气替油措施改进等8个方面治理对策,为保证油井正常生产奠定了良好基础。

High content of CO2 and H2S ,high salinity of formation water,and high content of Cl^- in the Ha6 block will result in corrosion and scaling easily and have influence on normal production of oil wells.Coexistence of CO2 and H2S may cause corrosion in the block ,and its main influencing factor is the value of Pco2/PH2s.The solubility of the formation water may decrease and then scale may be formed because the drop of temperature and pressure may have influence on the scale-forming ion in the formation water.In the process of aciding,flowback of residual acid will make corrosion and scaling of the pipe string after corrosion inhibitor was adsorbed by the mineral in the strata.During the oil displacement by gas injection,dissolved oxy- gen may result in corrosion and scaling of the pipe string.The present situation of corrosion and scaling was analyzed from the aspects of position,fracture and cavern zone,production string,water-bearing in produced liquid and aciding measure.The results show that the overall performance of corrosion and scaling is slight, but it should be paid attention.At present,the sulfur-tolerant oil tube and casing is used mainly and anode forced current cathodic protection in deep wells is adopted for anticorrosion on ground equipment and pipeline.Based on former research,eight countermeasures were put forward,such as determination of tubing material,the improvement of overflush and oil displacement measures by gas injection according to the value of Pco2/P2s,and it laid good foundation for ensuring the normal production of oil wells.