| CNOOC Fudao Ltd. | 100.00% | Hainan CNOOC Plastic Co., Ltd. | 100.00% |
| CNOOC (Hainan) E&P Gas Ltd. | 100.00% | Hainan Basuo Port Ltd. | 73.11% |
| CNOOC Tianye Chemical Ltd. | 92.27% | Shanghai Qionghua Trading Co., Ltd. | 100.00% |
| China BlueChemical Baotou Coal Chemical Industry Co., Ltd. | 100.00% | Hubei Dayukou Chemical Co., Ltd. | 83.97% |
| CNOOC Huahe Coal Chemical Ltd. | 100.00% | China BlueChemical (HongKong) Ltd. | 100.00% |