超深储层改造液对完井管柱的腐蚀与缓蚀*

井筒完整性对超深井安全高效生产意义重大,为揭示改造液对完井管柱的腐蚀规律,选取超深井改造常用的5种改造液与超级JFE 13Cr材质油管试片,通过金属挂片失重法和应力腐蚀实验,评价了超深层改造液对13Cr材料的腐蚀和新型高密度盐水加重压裂液缓蚀剂的缓蚀性能。结果表明,5种改造液对13Cr材质油管试片均存在一定程度的表面腐蚀,在140℃下的腐蚀速率为4.8~10.6 g/(m2·h)。当加载90%应力屈服强度时,试片在5种改造液中均出现不同程度的应力开裂裂纹,其中在硝酸钠加重压裂液中的应力腐蚀较为显著。在硝酸钠和氯化钙加重压裂液中加入由炔胺类化合物及一些金属化合物组成的高浓度缓蚀剂后,应力腐蚀显著缓解。该项研究对认识改造液的应力腐蚀、安全高效改造超深井油田具有借鉴意义。

Corrosion and Inhibition of Fracturing Fluids to Ultra-deep Completion String

Wellbore integrity is of great significance to the safe and efficient production of ultra-deep well.In order to reveal the corrosion law of fracturing fluid on completion string,five fluids commonly used in ultra-deep well and super JFE 13Cr tubing test pieces were selected,and the metal coupon weight loss method and stress corrosion experiment were adopted.The corrosion of 13Cr materials by ultra-deep fracturing fluid and the corrosion inhibition performance of the new high-density salt water aggravated fracturing fluid corrosion inhibitor were evaluated.The results showed that the 5 kinds of fracturing fluids all had a certain degree of surface corrosion on the 13Cr tubing test pieces,and the corrosion rate at 140℃was 4.8—10.6 g/(m2·h).When 90%stress yield strength was loaded,the test pieces had different degrees of stress cracking cracks in the five fluids.The stress corrosion in the sodium nitrate aggravated fracturing fluid was more significant.After adding a high-concentration corrosion inhibitor composed of acetylenic amine compound and some metal compounds to the sodium nitrate or calcium chloride aggravated fracturing fluid,the stress corrosion was significantly alleviated.This research was useful for understanding the stress corrosion of fracturing fluid and ultra-deep well stimulation safely and efficiently.