With the in-depth development of Bohai Oilfield, China National Offshore Oil Corporation (CNOOC), the water cut of some old wells become too high to produce while nearby remaining recoverable reserves are still considerable. In order to maximize recovery and reduce well construction cost, herringbone multilateral horizontal well drilling and completion technology is employed to increase drainage area of single well and make full use of well slot and old wellbore.

Considering the current development of oilfield and the geological characteristics of reservoir, the technical difficulties of herringbone multilateral horizontal well drilling and completion technology including high build-up rate, easy blockage of drilling tools in the sidetracking in open hole, easy collapse and instability of sandwich wall and high requirements for drilling fluid performance are analyzed and solved.

This technology has been successfully applied in three wells with total 6 branches and the production of three wells is twice higher than that of conventional horizontal wells with no water cut, which fully verified the reliability of the branch well tools and the feasibility of the technology.

Herringbone multilateral horizontal well drilling and completion technology provides a new idea for the treatment of low production and low efficiency wells in a sustainable way and will be widely promoted and applied in Bohai oilfield, which can also provide reference for other high water cut oilfields.

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