If pre-drilling mode was taken in an offshore oil development, PGB-free well drilling technology might be adopted for supplementary wells when the PGB slots were totally occupied.

• 摘要采用预钻井方式开发的海上油气田，对水下钻井基盘钻井槽孔用完后增钻的调整井，可采用无基盘钻井方式作业。