Study On Energy Consumption Evaluation And Optimization Technology Of Oil And Gas Gathering And Transportation System

Energy consumption of the gathering and transportation system can account for more than 70% of the total energy consumption of the surface engineering after the oilfield coming into high water cut stage.Therefore,it is of great significance to evaluate the energy consumption of the oil and gas gathering and transportation system and to optimize the operating parameters of the combination station for reducing the running cost of the gathering and transportation system and realizing the energy saving target.First,some basic problems in energy consumption analysis and evaluation of oil and gas gathering and transportation system were calculated and analyzed.The soil temperature field was calculated and the influencing factors were analyzed.The temperature profile of crude oil and its influencing factors along pipeline were calculated by thermal calculation.The hydraulic calculation of the gathering pipeline was carried out by five kinds of multiphase flow calculation methods.The gas phase conversion coefficients in the Baker method was fitted by the measured data.Based on the principles of heat transfer,a mathematical model of the temperature change in the heat tracing pipeline was established and the fluid temperature profile was obtained.The effects of heat tracing flow rate and temperature on the outlet temperatures of the cold fluid,hot fluid and the back pressure of the wellhead were discussed.The influence of different factors on critical flow rate were calculated and analyzed,which can provide theoretical support for reforming of the gathering pipeline of the oil and gas gathering and transferring system.According to the first law of thermodynamics,based on the energy evaluation index,the energy consumption for the combination station,pumps and boilers were carried out.Energy consumption data of the station and subsystem were obtained and the weak links of the use of energy were analyzed.It was clear that increasing the efficiency of pump and boiler and improving process were the effective way to reduce the energy consumption of the united stationAn optimized mathematical model was set up by taking the annual operating cost as optimal objec,the height of oil-water interface in pre-separator,the operating pressure of the oil and gas separator,the concentration of chemical agent,the settling time of the settling tank,the dehydration temperature of the electric dehydrator,the oil-water interface height and the external pressure of the electric dehydrator as the optimal variables and the process conditions as constraint conditions.The model was solved by random test method and the optimal operating parameters under certain production conditions were obtained.Sensitivity analysis of the related parameters was carried out.It was showed that saving energy and reducing consumption can also be achieved by the optimization of the running parameters.