基于R/S分析法的调剖注入压力动态变化特征量化评价

Quantitative Evaluation of Dynamic Varying Characteristics of Injection Pressure in Profile Control Based on Rescaled Range( R / S) Analysis Method

运用R/S分析法和分形理论计算调剖注入压力时间序列的Hurst指数及分形维数。对王窑长6油藏的6口井弱凝胶调剖注入压力曲线进行了实例计算。结果表明,调剖注入压力序列Hurst指数均大于0.5,平均值0.956 2,对应分形维数1.043 8。分段拟合时第一阶段Hurst指数平均值0.718 3,中后期0.969 4,对应分形维数分别为1.281 7和1.030 6,调剖注入压力变化具有明显的阶段性,中后期注入压力上升的概率远高于初期,与分析堵剂在地层运移规律具有一致性。R/S分析法量化评价调剖注入压力是可行的。

The Hurst index and the fractal dimension of the time series of the injection pressure in profile control are calculated using R / S analysis method and fractal theory. The injection pressure curves of 6 injection wells in weak gel profile control of Wangyao Chang6 reservoir are analyzed and calculated by using the R / S analysis method. The results show that the Hurst indexes of the entire injection pressure sequences of 6 injection wells are all higher than 0. 5,their average value is 0. 956 2,and the corresponding fractal dimension is 1. 043 8. As for piecewise fitting,the average value of the Hurst indexes in the initial stage is 0. 718 3,it is 0. 969 4 in the middle and later stage,and the corresponding fractal dimension is 1. 281 7 and 1. 030 6 respectively. Profile control injection pressure varition has obvious piecewise feature,the probability of injection pressure rising in the middle and later stage of injection is much higher than that in the initial stage,which is consistent with the migration law of profile control agent in reservoir. The quantitative evaluation of profile control injection pressure using the R / S analysis method is feasible.