The West Crude Oil Pipeline, 1500km long, a newly constructed pipeline, was put into operation in August 2007. Several crudes with different wax content and thus different pour point/gel point are pumped through the pipeline in batch, with the gel point ranging from -10°C to 10°C. In winter, the lowest ground temperature will be as low as 2°C at the depth where the pipeline is buried. The pour-point-depressant (PPD) was used to reduce gel point of the waxy crudes to ensure safety of pipeline operation. To make sure that the selected PPD reduce gel point effectively, field tests were conducted from September to November in 2007 to prepare for winter operation. The PPD was injected to the waxy crudes at the initial station, and gel points and densities were measured at the initial station and several intermediate stations along the pipeline. The test results show that the PPD may effectively reduce the gel point of the crude, but the effectiveness depends on the composition of crude oil; the reduced gel point of the crude may recover during pipelining; reheating temperature at the intermediate stations may seriously affect the flow properties of the PPD beneficiated crude. Reheating the PPD beneficiatcd Tuha crude oil to the temperature range of 20 ～ 35°C results in poor flow properties. This indicates that the reheating temperature at the intermediate stations must be properly controlled to avoid falling into this temperature range. Based on this field test, the pipeline was safely operated for last winter.
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