Forward And Reverse Transporting Optimization Technology Reseach Of Su Cuo Oil Pipeline

With the decrease of the production of Hulun Buir oilfield, Su Cuo oil pipeline is gradually into the low throughput operation stage. In order to ensure the safe and economic operation, forward and reverse transporting process for Su Cuo oil pipeline has been established in 2013. However, due to the lack of theoretical research and referential cases, the operation scheme made by subjective experience had affected the safety and economy of the pipeline operation. Therefore, it is significant to carry out forward and reverse transporting process of hydraulic and thermodynamic characteristics, as well as optimization technology. The main achievements obtained are as follows:Firstly, according to the characteristics of forward and reverse transporting process, mathematic models were established to describe thermodynamic characteristics of the steady and unsteady state conditions, which were solved by the combination of finite element method and finite difference method.For the steady state, the total heat transfer of pipeline was calculated by reversed calculation. It showed that the average relative errors of two pipelines temperature drop were 2.41% and 3.25%, which greatly improves the accuracy of thermodynamic model. In view of the unsteady reverse transporting process, "total heat transfer coefficient" in different tubes was calculated by reversed calculation as well to describe the thermal characteristics. The change characteristics of loss regularity and oil temperature were analyzed. Moreover, the critical minimum throughputs of typical conditions were determined limits to the pour point of crude oil above 3 degrees.Secondly, the forward and reverse transporting process of Su Cuo pipeline was divided into four typical operating stages based on wax deposition process. The distribution of Reynolds number in each stage was divided into different conditions by two-step-cluster method and the hydraulic friction coefficient calculation formula of each condition was certained by using nonlinear least squares estimation of regression analysis the actual production data. And the hydraulic calculation model under different stages of Su Cuo pipeline was determined. Error analysis under the four conditions showed that the average relative errors of first pipeline were dropped to 10.43%, 11.99%, 14.16% and 3.87% from 21.64%, 17.26%, 17.04% and 19.53%. The average relative errors of second pipeline were dropped to 6.02%, 6.22%, 11.98% and 4.01% from 23.31%, 24.27%, 27.84% and 21.07%.Finally, the forward and reverse transporting process optimization mathematical model of Su Cuo oil pipeline was established, in which the least production operation consumption cost in certain time is taken as objective function, the days and throughput of forward and reverse process and operating parameters of the pipeline are taken as decision variables, considering the constraint condition of completing the throughout task safety of pipeline. The calculation results showed that the forward and reverse transporting process operation consumption cost of the pipeline was reduced by 12.16%.Through the optimization solution, forward and reverse transporting operation schemes in different seasons and monthly planned throughput tasks could be made, providing effective technical guarantee for safe and economic operation of Su Cuo oil pipeline.