The produced fluids from heavy oil reservoirs in the Northwest Oilfield exhibit strong emulsification and high viscosity, making conventional pre‑dehydration processes ineffective. As development of the field progresses, the overall water cut of the produced fluids continues to rise, overloading the gathering and transportation processing system and thereby limiting the field’s liquid‑lift capacity; meanwhile, the long‑distance transportation of produced water results in high operating costs.

The fully gravity-balanced integrated water–oil separation unit integrates gas–liquid separation, self-optimizing coalescing water removal, inclined-plate coalescence, natural-gas separation and mist elimination, and buffer functions into a single system. It operates without chemical dosing, achieving an average oil content of 2.9% in the oil outlet (design target <10%) and an average dehydration efficiency of 92.9%. The average oil concentration in the water is 4.0 mg/L, with suspended solids at 42.0 mg/L—both figures better than the design targets (<100 mg/L)—thus meeting the reinjection water quality requirements specified in the “Water Quality Standards for Water Injection in Carbonate Fracture–Cavity Oil Reservoirs.” The average electricity consumption is 0.08 kWh per cubic meter of treated fluid.

The facility has achieved a breakthrough in the “three-in-place” treatment technology for ultra-heavy oil produced fluids, effectively reducing operating pressure in gathering and transportation pipelines and the processing load at integrated stations, substantially lowering energy consumption associated with pump transportation and pipeline heating, and enhancing the block’s risk-resilience.