基于改进DGM (1, 1)模型对管道壁结蜡厚度预测
（中国石油天然气集团有限公司华北油田分公司，河北 任丘，062552）
摘要：为研究管道壁结蜡沉积厚度随时间的变化规律，基于灰色理论模型建立了改进DGM (1, 1)模型，分别以室内环道实验和现场管道数据为例，引入弱化缓冲算子和平移变换提高原始序列的光滑性，并进行不同模型的检验和对比。结果表明，传统DGM (1, 1)模型的平均相对误差较大，经弱化缓冲算子处理后改进模型的误差大幅降低，且d2更适合结蜡厚度这类短序列、宽间距序列的预测；对原始序列进行平移变换可提高序列光滑性，不同原始序列对平移变换函数的偏移量存在选择性；弱化缓冲算子对模型改进的效果远大于平移变换；应用改进GM (1, 1)模型对管道壁结蜡厚度进行预测是可行的，该方法具有一定的推广价值。
关键词：管道壁；DGM (1, 1)模型；蜡沉积；结蜡厚度；弱化缓冲算子；平移变换
中图分类号：TE973 文献标识码：A
Prediction of wax thickness in pipeline wall based on modified DGM (1, 1) model
YANG Ligong
(PetroChina Huabei Oilfield Company, Renqiu, Hebei 062550, China)
Abstract: In order to study the change of wax deposition thickness in pipeline wall with time, an modified DGM (1, 1) model was established based on the grey theory model. Taking indoor loop experiment and field pipeline data as examples, the weakening buffer operator and translation transform were introduced to improve the smoothness of the original sequence, and the different models were tested and compared. The results show that the average relative error of the traditional DGM (1, 1) model is large, and the error of the improved model is greatly reduced after the weakening buffer operator treatment, and the d2 operator is more suitable for predicting the wax thickness of short sequence and wide spacing sequence. Translation transformation of the original sequence can improve the smoothness of the sequence, and different original sequences have selectivity on the offset of translation transformation function. The effect of weakening buffer operator on model improvement is much better than that of translational transformation. It is feasible to use the modified GM (1, 1) model to predict the wax thickness in pipeline wall, and this method has certain popularization value.
Keywords: pipeline wall; DGM (1, 1) model; wax deposition; wax thickness; weakening buffer operator; translation transformation
中国大部分原油为高含蜡、高凝点、高黏度的“三高”原油，含蜡原油在井筒举升或管输过程中难免出现介质热力特性改变的情况。当管道壁温度低于析蜡点温度时，在分子扩散和剪切弥散的作用下，原油中的蜡晶分子析出并附着在管壁上，降低了管道的输送能力和流通面积，严重时还会引发堵管事件 [1–3]。此外，目前原油管输介质多为多相混输，混输对于蜡沉积的影响往往较单相流更为严重 [4–5]。因此，对管道壁结蜡厚度进行预测和研究，对于提高井筒及地面的流动保障安全性具有重要意义。
虽然管道壁结蜡厚度随沉积时间的延长而增长，但增长速度却随原油组成、油壁温差、流速、流型的不同而变化。目前，研究管壁蜡沉积多采用冷板法、冷指法或环道实验[6]，但需耗费大量的人力、物力，故需建立管壁结蜡厚度预测模型，用于反映沉积程度随时间的变化趋势。灰色理论模型适用于随机小数据不确定系统，建模过程相对简单，无需