Study On Dewaxing Period And Dewaxing Technology Of Low Volume Waxy Crude Oil

When the oil field enters the later stage of production,the fluid production of oil wells is insufficient,and even some oil wells are exhausted and shut down.The oil pipeline transportation of most oilfields decreases and enters the low-volume operation period.Waxy crude oil accounts for more than 80% of the crude oil produced in China.Compared with normal pipelines,waxy crude oil is easier to wax in low throughput operation,and its wax removal cycle is more frequent.Aiming at the serious problem of wax deposition in low waxy crude oil pipeline,this paper calculates the wax deposition rate of low waxy crude oil pipeline,optimizes the wax removal period,and puts forward a feasible wax removal process.Firstly,the variation of operation parameters of pipeline under the condition of low throughput is analyzed.When calculating the minimum throughput,the friction heat generation and the influence of wax deposit on pipeline operation are considered.Secondly,the thickness of sedimentary layer is calculated by analyzing the sedimentary condition and mechanism of waxy crude oil on low-throughput pipelines.In the process of calculating deposition rate,considering the interaction between wax deposit layer and pipeline operation,small pipe segments are divided,and the thickness of deposit layer is calculated by iterative method through programming.Through the analysis of the example of wax deposition prediction,the results of different distribution patterns of wax deposits in winter and summer in low-volume waxy crude oil pipelines are obtained.Then,according to the above results,it is proposed that the safe wax removal limit is that the thickness of deposit layer at the thickest wax deposit in winter is larger than that at the thickest wax deposit layer,and the proportion of deposit layer thickness of pipeline in summer is more than 30%.Then the economic wax removal cycle of pipeline is calculated.Compared with the safe wax removal cycle,the shorter period is selected as the optimal wax removal cycle of pipeline.Finally,through the analysis of the pipeline wax removal process,the cylindrical wax removal device was designed and improved to solve the problem of wax removal plugging in low-volume waxy crude oil pipeline.