Improvement and application of electric drifting and fishing technique in separate layer water injection wells of Chengdao Offshore Oilfield

In view of severe corrosion and scale-building in downhole water injection pipe string, which leads to tight hole, stuck pipe and instrument lost in hole during logging, the electric scale-scraping drifting and fishing technique was developed, which integrates mechanical and electrical instruments, and directly controls the electric scraper and fishing tools to scrape the wellbore or fish the lost instrument through logging wireline; it is characterized by large scraping torque, high operation efficiency and large fishing coverage. It has been used in four wells at site with a success rate of 100%. It works effectively, has promoted the development of separate layer water injection technology in offshore wells and provides a technical means for steady production and increase in production of offshore oilfields.