Pipelining of Viscous Waxy Crude With the Pour-Point-Depressant Beneficiation: Successful Experience in the Lu-Ning Pipeline

The Lu-Ning Pipeline in the eastern China, 655.37 km long and 720 mm O.D., transports viscous Shengli waxy crude with a wax content of ca 15.24%(wt), a density of 922 kg/m³ at 20°C , a gel point of 24°C, and a viscosity of 3210 mPa·s at 25°C. It was designed as a hot oil pipeline. In the mid 1990’s, with decreasing of the crude throughput, the fuel consumption for pipelining per ton of crude increased dramatically. For reducing fuel consumption, the technology of pour-point-depressant (PPD) beneficiation was adopted. Great success was achieved. With a PPD dosage of 50 ppm and a beneficiating temperature of 60°C at the initial pumping station, the gel point of the crude was reduced by 16°C, and the viscosity at 25°C was reduced by 87%. As a result, the crude temperature at the inlet of the intermediate heating stations was lowered from 34°C to 27±1 °C. This resulted in annual 17200 tons of fuel oil saving. Thanks to improvement of the crude flow properties, running heating stations were reduced from twelve before using the PPD to only one (the initial station) in summer, seven in winter, and two to five in spring and autumn depending on ground temperature. This was the pipeline with the longest distance, the largest diameter, the largest throughput and the most running pumping stations in China that ever used the PPD-beneficiation technology. We believe that experiences gained from this pipeline and other pipelines operated by the SINOPEC Pipeline Transport and Storage Company will be helpful to safe and economical operation of hot waxy crude pipelines.