Abstract: When the process of extraction of oil from an offshore oilfield enters the advanced stages, the water content in the extracted fluid can be above 90%. The water quality is complex with many types of pollutants and highly emulsified water. Therefore, a key consideration in the production process of offshore oilfields is the efficient and economical treatment of the oil-containing produced water to make it suitable for discharge and recover oil pollutants. In this study, we developed a hydrophilic and hydrophobic combined fiber coalescence separator with composite fiber shapes using fiber induction and X/Ω-weaving. The separator is designed based on experimental observations of the mechanism of structure coalescence in the physical oil removal method. A pilot test was performed on an oil exploration platform in the Bohai Sea. At the designed flow rate, the separator reduced the total concentration of petroleum in the produced water from 2000 to 3000 mg/L to below 60 mg/L, with an average oil removal efficiency of 98.24%. Furthermore, it effectively reduced the number of organic compounds present in the water from 120 to 17 and removed 70% of the SS. The test results show that the proposed device can be used fr produced-water treatment on offshore platforms.