The Thermodynamics Analysis For The Heavy Crude Gathering And Transferring System

In the process of heavy crude gathering and transferring, the heating and driving consumptions are far higher than that of thin oil, because the upper transport temperature is demanded and the resistance loss of gridiron in the process is so large simultaneously. Thus the energy consumption analysis and appraisal of heavy crude gathering and transferring system is very important to reduce the system energy consumption effectively. Firstly the property of heavy crude, the main technique of exploitation and the technological process of the component parts of the heavy crude gathering and transferring system such as the wellhead manifold, the metering station, the transfer station and the central treating station are introduced. Then the fundamental conception of energy system and the thermodynamics analysis method are explained.Contrasted with enthalpy analysis and entropy analysis, exergy analysis is scientific and practical. Exergy analysis criterion includes appraisal criterion and analysis criterion. Thermodynamics perfection degree and exergy efficiency, which belong to the appraisal criterion, can be directly obtained from the fundamental exergy equation and the universal exergy equation. They can make macroanalysis for the whole energy consumption condition of the equipment or the system. Otherwise, two kinds of analysis criterion, exergy loss coefficient and exergy loss rate, can distinguish the rationality from the process of energy transformation, transmission and service."Two Box"engineering exergy analysis method includes"black box—white box"exergy analysis method of equipment and"black box—gray box"exergy analysis method of system. They have already been used successfully in the oil field production system and are simply and practical. Based on above, the gray box model of the combined station subsystem, the gray box model of the transfer station subsystem, the energy loss model of the pipe network subsystem and the gray box model of the whole gathering and transferring system are set up. Then some heavy crude gathering and transferring system in Liaohe Oil Field is analyzed for an example. The result indicates that energy efficiency of the system is 30.40%, which belongs to moderate level among the oil fields. Three subsystems all have a certain potential of energy conservation and some relevant suggestions are proposed.