基于改进黄金分割法的钻井液流变模式优选

钻井液流变参数的计算和流变模式的优选对于钻井作业的顺利进行至关重要。结合数值计算方法、回归分析和最优化的理论,在穷举法的基础上,引入相关指数、残差平方和以及残差方差3个评价标准,利用黄金分割法加快有根区间的收缩速度,提出了改进的黄金分割搜索算法。利用该方法,不用给定迭代初始值,收敛性好,克服了已有钻井液流变模式优选算法的缺点,同时适用于2参数、3参数、4参数流变方程的参数计算与流变模式优选。借助MATLAB语言编制相应计算程序对大量数据进行计算,并与前人的计算结果进行比较,结果表明:所采用的3种回归评价标准是有效的,与改进的黄金分割搜索算法相结合,能够回归出钻井液的流变参数,并准确地优选出流变模式,残差方差的计算结果平均降低了19.70%,计算结果精度更高。 

Optimization of Drilling Fluid Rheology Pattern Using Improved Golden Section Method

Rheological parameters of drilling fluid and selection of rheology pattern play an important role in drilling operation. Using exhaust algorithm and other methods, such as numerical computation method, regression analysis and optimization theory, three evaluation indices, i.e., correlation index, sum of squares of residues and variance of residues are introduced. Using golden section method, the contraction of the root interval can be accelerated. These studies give birth to the so called improved golden section method. In this improved golden section method, initial iterative values become unnecessary, and the method has good convergence, getting rid of deficiencies of the rheological model presently in use. This method is suitable for the parameter calculation and optimization of rheological patterns using 2-parameter, 3-parameter and 4-parameter equations. Using computer language MATLAB, large scale computation can be realized. Comparison of the computation results and those of others shows that the three evaluation indices presented are useful, and when used in combination with the improved golden section method, rheological parameters can be calculated, and rheological model optimized with good accuracy. The computational result of the variance of residue is reduced by 19.7%, a higher computational accuracy.