气制油合成基钻井液低温高压条件下流变模式研究

摘要

Drilling fluid rheological model is a quantitative characterization of rheological properties of drilling fluid,which plays a very important role in hydraulic calculation of drilling operation. In order to investigate theological model in low temperature and high pressure,a fully automatic rheometer-FannIX77 was used to measure theological parameters of gas to liquid (GTL) based drilling fluids with two different water oil ratios. The experimental results showed that the shear stress increased with the increase of pressure,and rheological curves didn't pass the base point and the curve slop is ever increasing. The regressed results showed that Bingham model,Casson model and H-B model can reflect rheological properties of the two GTL based drilling fluids under low temperature and high pressure,and power-law model is relatively worse. Casson model has the best matching results compared with Bingham and H-B model. Bingham model is recommended for hydraulics calculation.%钻井液流变模式是对钻井液流变特性的定量表征,对钻井过程中的水力学计算具有十分重要的作用.为研究气制油合成基钻井液低温高压条件下的流变模式,用FannIX77全自动钻井液流变仪测定不同油水比的流变参数并进行了分析.试验结果表明,低温条件下气制油合成基钻井液体系的剪切应力随着压力的升高而增大;流变曲线不经过原点,且曲线斜率不断增大.应用最小二乘法和线性回归对两种体系的流变曲线进行了拟合,结果表明,对于不同油水比的合成基钻井液体系,宾汉、卡森、HB三种流变模式均能较好地反映低温高压条件下钻井液的流变特性,幂律模式相对较差;与宾汉、HB模式相比,卡森模式的拟合效果最佳.为便于水力学计算,建议用宾汉模式来表征气制油合成基钻井液的流变特性,并进行水力学计算.