大温压域钻井液流变参数预测模型

Model for Predicting Drilling Fluid Rheological Parameters in Wide Temperature and Pressure Range

钻井液流变参数的精准预测对于高温高压井水力参数及井筒压力精确计算、保证钻井安全具有重要意义。基于构建的钻井液流变性实验数据库,对不同钻井液体系大温压范围内九种流变模式进行了适用性评价,其中油基钻井液体系优选了赫巴流变模式(中低温低压)和四参数流变模式(高温高压),水基钻井液体系在大温压范围内优选了双曲流变模式。优选的流变模式是高温高压井井筒压力准确预测的基础。基于实验数据开发与多元非线性拟合,提出了一种新的适用于大温压范围下不同钻井液体系、不同流变模式的流变参数预测模型,并对某高温高压井井筒压力进行了计算验证。计算结果表明:以双曲模式流变参数模型为基础计算的井底压力误差为1.31%,可以满足深层、超深层高温高压井井筒压力精确计算要求。

Accurate prediction of drilling fluid rheological parameters is of great importance to the accurate computation of high temperature high pressure(HTHP)hydraulic parameters and borehole pressure,and to maintain the safety of drilling operation.Based on the database of drilling fluid rheological parameters obtained in laboratory experiments,nine flow models were evaluated for their adaptability to different drilling fluid systems in a wide temperature and pressure range.Among these models,the Herschel-Bulkley model(medium and low temperature,low pressure)and the four-parameter flow model were selected for evaluating their adaptability to oil based drilling fluids,the hyperbolic flow model was selected for evaluating its adaptability in a wide temperature and pressure range to water based drilling fluids.The selected flow models are the bases for accurately predicting the borehole pressures in HTHP wells.Based on the experiment data development and multivariate nonlinear fitting,a new model was established for predicting the rheological parameters of different drilling fluid systems with different flow models in a wide temperature and pressure range.This new model was then verified with borehole pressure data obtained from an HTHP well.The verification results show that the error existed for using the hyperbolic flow model as the basis to calculate the bottom hole pressure is 1.31%,indicating that the new model has satisfied the needs for accurate computation of borehole pressures in deep and ultra-deep HTHP wells.