油基钻井液低温流变特性实验研究

Study on Low Temperature Rheology of Oil Base Drilling Fluid

采用正交实验和方差分析的方法,通过测定油基钻井液的流变曲线,研究了低温下影响油基钻井液塑性黏度、动切力的主要因素。结果表明,当油水比一定时,润湿剂和降滤失剂的交互作用对钻井液低温下的黏度影响最大,其次是润湿剂和有机土。采用二元表分析方法,优选出对温度最敏感和最不敏感的2套配方体系。考虑油水比和基油的种类对温度敏感性最弱的配方低温流变性能的影响,结果表明在一定温度范围内,塑性黏度随温度的升高而近似线性降低,油水比越低,变化的幅度越明显。相同温度下,5#白油体系的黏度和动切力最高且对温度的敏感性最强,合成基体系黏度低且对温度的敏感性弱。最终得到一套适合深水钻井的对温度敏感性最弱的油基钻井液体系。

Using orthogonal experiment and variance analysis, the plastic viscosity and yield point of oil base drilling fluid at low temperature was studied through rheology measurement. At certain oil/water ratio, the synergetic action of wetting agent and filter loss reducer has the maximum effect on low temperature viscosity of oil base drilling fluid, higher than the effect exerted by wetting agent and organophilic clay alone. The effect of oil/water ratio and the type of base oil on the low temperature rheology of some oil base fluid having the lowest temperature sensitivity was studied. The lower the oil water ratio, the higher the plastic viscosity and yield point under the same temperature, and the temperature sensitivity of the fluid was increasing with increase in oil/water ratio. At the same low temperature, the #5 white oil base mud has the greatest plastic viscosity and yield point, and is more sensitive to temperature change. The #3 white oil, #0 diesel oil and synthetic base fluid have plastic viscosities with minor differences, and the synthetic base fluid has the lowest temperature sensitivity, which is suitable for deep water drilling. An oil base fluid that is most suitable for deepwater drilling and has the lowest temperature sensitivity is formulated: 270 mL synthetic oil + 3% emulsifier + 1% wetting agent + 30 mL CaCl2 water solution + 1% CaO + 3% filter loss reducer + 0.5% viscosifier + 1% organophilic clay, with a density of 1.2 g/cm3.