不同流变模式钻井流体圆管层流压耗的通用精确算法

钻井工程常用的管流压耗分析方法计算精度低,且不能适应一些相对复杂的流变模式。在已知流变方程的条件下,利用通用圆管流量方程建立流量与管壁切应力或管壁剪切速率的精确关系式,通过该关系式由给定的流量求解管壁切应力,进而获得圆管层流压耗精确值。这种方法适用于所有流变模式的钻井流体圆管层流,具有普适性好、建模过程简单、模型精度高等特点;室内试验表明该算法相对于传统算法是一种更加精确的圆管层流压耗计算方法;该方法的提出为一些复杂的流变模式在钻井工程及其他工程领域的推广应用提供了良好的基础。

A high precision method for calculating laminar pressure drop of drilling fluid in pipe flow with different rheological models

Conventional analytical method of pressure drop in drilling engineering has poor accuracy and it is unavailable for some complex rheological models. It is expected and possible to establish an accurate relationship between pipe flow and shear stress or shear rate at pipe wall from pipe flow equation if rheological equation of non-Newtonian fluid is given. Once the pipe flow is given, shear stress at pipe wall is also available, and then the accurate result of pipe laminar pressure drop can be obtained. This solution is adaptable to any time-invariance rheological model of pipe laminar flow, and has good universality, simple modeling process, and high accuracy. Indoor experimental results show that, compared with the conventional pressure drop method, the new method is more accurate for calculating pipe laminar pressure drop. This method provides a good foundation for some complex rheological models applied in drilling engineering and other engineering fields.