顺序输送原油管道中减阻剂效果的评价方法

An evaluation method for the effect of DRA in a batch-transportation crude oil pipeline

在顺序输送管道加注减阻剂现场试验中,首末站压差取决于减阻剂的作用效果及管道中各品种原油所占管容的比例,因此不能沿用输送单品种原油管道减阻率的计算方法进行减阻剂效果评价。依据乌鄯原油管道顺序输送北疆油、哈国油的运行实例,对顺序输送过程中减阻剂作用效果提出了评价方法。当顺序输送管道首站注入的加剂油与末站排出的未加剂油为同种原油时,管道中各品种原油所占管容比例不变,管道首末站压差的降幅仅取决于减阻效果;对应注入加剂油的管长,通过理论计算得到该管段输送未加剂原油产生的摩阻;首末站压差降幅与该摩阻的比值即为减阻剂对管道输送该原油产生的减阻率。现场试验证明:添加减阻剂A,在410~600 m3/h流量范围内,对乌鄯线输送哈国油减阻率为31.4%~34.7%;添加减阻剂B,在550~933 m3/h流量范围内,减阻率为15.8%~17.2%。

For the field test of crude oil added with drag reduction agent （DRA） in a batch-transportation pipeline, the pressure difference between the initial station and the terminal station depends on the effect of DRA and the proportions of different crude oils in the pipeline, so the DRA effect can not be evaluated by the traditional method which is applicable to single crude oil pipeline. In this paper, considering the practical batch transportation of North Xinjiang crude oil and Kazakhstan crude oil via the Urumqi-Shanshan Crude Oil Pipeline, a new method was proposed to evaluate the effect of DRA in the process of batch transportation. If the crude oil with DRA injected at the initial station is of the same type as the one without DRA off-taken at the terminal station, and the proportions of different crude oils in the pipeline are constant, the drop of the pressure difference between the initial station and the terminal station is only attributable to the effect of DRA. Based on the length of the pipeline section transporting crude oil with DRA, the friction generated by the transportation of crude oil without DRA in this pipeline section was theoretically calculated. The ratio of the drop of pressure difference between the initial station and the terminal station to the friction is defined as the drag reduction ratio of DRA contributing to the crude oil in the pipeline. The field test results show that, when DRA-A is added, the drag reduction ratio for the transportation of Kazakhstan crude oil via the Urumqi- Shanshan Crude Oil Pipeline is 31.4%-34.7% if the flow rate is 410-600 m3/h; when DRA-B is added, the drag reduction ratio is 15.8%-17.2% if the flow rate is 550-933 m3/h.