Abstract: The determination of rheological parameters and the optimization of rheological pattern are the basis of drilling fluid design and circulating pressure loss calculation. For drilling fluid model of nonlinear rheological pattern，a regression model of nonlinear rheological pattern is established based on Gauss-Newton method and the readings of a six-speed viscometer. According to the relevant parameter R to measure the deviation relationship，matched computing software to select the rheological pattern for drilling fluid is developed with C# as the programming language，which outputs the rheological curve of each rheological pattern. Validation is also made by integrating with the measured data. The algorithm can determine the rheological parameters for drilling fluid of nonlinear rheological pattern，and select appropriate rheological pattern by comparing the correlation coefficient，which provides an effective tool for quickly selecting rheological pattern for drilling fluid.

Key words: drilling fluid, rheological parameters, rheological pattern, Gauss-Newton method; computing software

摘要： 钻井液流变参数确定以及流变模式优选是钻井液设计、循环压耗计算的基础。针对非线性流变模式的钻井液模型，基于高斯-牛顿法，通过六速粘度计的读数，建立了非线性流变模式的回归模型；根据衡量偏差性关系程度的相关参数R，以C#为编程语言，开发了配套的钻井液流变模式优选计算软件，可输出各流变模式的流变曲线，并结合实测数据进行了实例验证。该算法可以确定非线性流变模式下钻井液的流变参数，并通过比较相关系数优选出合适的流变模式，为快速优选钻井液流变模式提供了有效的工具。

关键词: 钻井液, 流变参数, 流变模式, 高斯-牛顿法, 计算软件