Analysis And Optimization Of WH Heavy Crude Pipeline's Safe And Economical Operation

WH heavy crude pipeline is the first domestic long-distance high pressure pipeline transporting heated heavy oil diluted by gas oil,so there is no practical operation and management experience to draw upon.Its transportation characteristics are different from light oil pipelines for unstable operation area;when the original viscosity is high,the restarting process may fail due to the viscosity increase caused by temperature drop after shutdown.Therefore it is necessary to study the pipeline transportation characteristics and shutdown restart strategy which will provide technical support for pipeline safety,economic operation and improvement.Taking actual operation into consideration,the SPS model is established to calculate and analysis steady operation pressure of this pipeline with different flow and oil viscosity,then rendering pipeline characteristic layout to recommend the reasonable dilute ratio and operation parameters when transporting heavy oil with different viscosity.Within the recommend dilution ratio range,simulate the process of the shutdown and restart with different flow,when transporting 20% and 25% dilution ratio of Z101 well WH oil,safe shutdown time is more than 72 hours,when it comes to 15% dilution ratio,if it can't meet the safe shutdown time of pipeline repair time,replacing the lower dilution ratio blend oil with higher one before shutdown is recommended;when transporting 20% and 25% dilution ratio of D305 well WH oil,safe shutdown time is less than 72 hours under 6.0MPa restart pressure,when transporting 25% dilution ratio of D305 well WH oil,safe shutdown time is 72 hours under 7.2MPa restart pressure,equipping with screw pump of design pressure 8.0MPa at initial stationse is recommended during developing high viscosity heavy oil similar D305 wells.Systematically analyses influence on cost and produce caused by dilute ratio in the chain of mining,transportation and refining of oil.The optimal dilute ration of Z101 well WH oil is 20% if only consider the transmission pipeline system;Considering recycled grams of coking gas oil and petrochemical company's processing costs,economical ratio recommended is 15%;besides,experimental effect of dehydration in WH field processing station should be the foundation of the best systematical optimum.An advice is provided to increase dilution ratio and meet the safe shutdown time when maintenance time is not enough by adding gas oil dilution spot at the inlet of export pump in the first station.