Application of water quality treatment technology in an offshore oilfield

Aiming at the problem that the current water quality cannot meet the water injection standard in an offshore oilfield, based on the analysis and understanding of the production water quality, combining with the specific condition of the platform, a CDFU (compact cyclone dissolved air flotation) with two-stage filtration was developed, accompanied by a miniaturized water quality improvement process with water treatment chemicals. CDFU has a simple structure, small footprint, flexible placement, and strong anti-fluctuation which can effectively overcome the problem of limited platform space and large fluctuation of incoming water. Besides, the high efficient water treatment agent can resolve the blackening and sedimentation problem caused by the high content of H₂S. Satisfied results were achieved in the filed application, with the average oil mass concentration, the average suspended solids mass concentration, and the average particle size was 4.25 mg/L, 0.45 mg/L, and 1.35 μm, respectively. And the effluent quality was up to A2 reinjection water requirement index. Therefore, the feasibility of process was verified. The successful test of miniaturized water quality improvement process offers an important reference for the treatment of water containing sulfur in offshore oilfields.