幂律钻井液流变参数估计的改进算法  

An Improved Algorithm of Rheology Parameters of Power-law Drilling Fluid

作　　者：刘东[1] 

机构地区：[1]中国石油辽河油田公司钻采工艺研究院,辽宁盘锦124010

出　　处：《江汉石油职工大学学报》2008年第2期31-33,40,共4页Journal of Jianghan Petroleum University of Staff and Workers

摘　　要：钻井液的幂律流变模式的流变参数估计大多使用线性回归方法进行求解,然而线性回归方法改变了测量误差的统计特征,使所得到的流变参数估计不具有无偏性和方差最小等特点。针对幂律流变方程的特点,人们提出了一个非线性最小二乘估计的算法,该算法不需要人工给定迭代初始值,迭代过程稳定收敛到最小点,不会陷入极小点陷阱,收敛速度很快。它是一个全局优化算法,所得到的流变参数估计具有拟合残差近似无偏性和方差几乎最小的优良统计特征。大量的实际钻井液算例表明,该方法具有比线性回归方法更小的拟合方差和相近的均值,拟合残差统计特性优于线性回归方法。它可以应用到钻井液幂律流变模式中,解决流变参数的确定、钻井液流变模式优选、钻井液性能调整和评价等许多问题。Frequently the linear regression method is used in the approximation of the rheological parameters of power-law model of drilling fluid. However it alters the statistic nature of measurement errors and can not give unbiased results and results with minimum variance. A new least square approximation algorithm is developed based on the characteristics of the power-law model. This new algorithm has no requirement of defining an iterative initial value, gives a converging minimum value, has no possibility of running into the ＂ minimum value＂ trap and has a fast convergence. The new algorithm is a global optimization one with nearly unbiased results and nearly minimal variance. Field practices show that the new algorithm is better than the conventional linear-regression method and can be used in the determination of the rheological parameters of the power-law model, the optimization of the rheological model and the evaluation of the drilling fluid properties, etc.

关 键 词：钻井液 流变方程 幂律模式 线性回归 非线性回归 

分 类 号：TE21[石油与天然气工程—油气井工程]