APPLICATION OF TWINHOLE-IN-MONOBORE TECHNOLOGY IN OFFSHORE BOHAI OILFIELD

The twinhole-in-monobore technology have been successfully used to drill two directional branches in the same wellbore in offshore Bohai, setting the following records,i.e.,the 9(4/6)″ surface casing for two wells run in the 30″ pilot pipe; successful completions of the two wells with 9(4/6)″ casing in the 26″ hole; accurate orientation of two wells in the same hole; completion of the 7″ casing using original wellhead. Gyroscope steering MWD system was used to locate the four targets of the two wells, and precise well trajectory control was achieved. This technology is beneficial for cost reduction in offshore drilling and could improve the efficiency of platform usage.