COOEC has developed multiple technologies for dimensional optimization of 300m deepwater flexible jackets, dynamic analysis, fatigue analysis, node reinforcement, and hydrostatic collapse resistance design and independently developed a technology system for the construction of deepwater flexible jackets covering the welding of high-strength steels, evaluation of weld defects, dimensional control and precision control, control of lateral cracks, fit-up and construction, and multi-machine collaborative lifting. We made breakthroughs in the special technologies for the testing of underwater grouting and injection systems and the reduction of wind/vortex-induced vibrations; established recommended practices and other company standards for weight control during modular construction and for the testing of underwater grouting systems; established standard procedures for various tasks such as refined three-dimensional design and construction and human-machine interface/ergonomic design; implemented the technologies for real-time internal wave monitoring, treatment of sand waves and sand ridges, and evaluation and upgrading of offshore vessels’ ultimate capacities; improved the system of installation technologies; and ensured efficient utilization of offshore vessels. The technological innovations and achievements have been successfully used in multiple projects, including Lufeng 14-4 oilfield, “Haiji-1”, Lufeng 12-3 oilfield, and Liuhua 11-1 oilfield.