【摘要】 水基恒流变钻井液是一种适用于深水钻井作业的新型工作流体,目前关于该体系的报道较少。通过对一定温度压力下钻井液性能的检测以及流变模型分析,研究了水基恒流变钻井液的流变行为,并初步探索了恒流变机理。结果表明,在0.1~35.4 MPa范围内,当温度从4℃升高到65℃,黏度计读数φ6/φ3、动切力、塑性黏度等流变参数的变化幅度较小,分别在10~13、9~12、13~18 Pa及15~22 m Pa·s范围内,且φ6与φ3读数随温度呈"U"型分布;在温度压力组合条件下,拟合经验流变方程的相关性排序为:宾汉塑性≈幂律<卡森≈赫-巴≈罗-斯模型,其中双参数卡森模型的相关系数较高,且表达式简洁,适于描述水基钻井液的恒流变特性;以卡森模型为初始方程,引入T/P因子建立了高预测精度的动力学流变方程f(T,P,γ),相对误差平均值为7.19%±4.07%,偏差极大值集中在100(r/min)/65℃;分析了关键处理剂的分子形貌、结构及其与黏土片层的缔合作用,提出了基于分子形态的定性构效假设,揭示水基钻井液的流变稳定性本质。更多还原

【Abstract】 Consistent rheology water base drilling fluid, rarely reported presently, is a new working fluid used for deep water drilling. The rheological behavior and the consistent rheology mechanisms were studied by measuring the properties and analyzing the rheological model of the consistent rheology drilling fluid under certain temperature and pressure. It is demonstrated that in pressure range between 0.1 MPa and 35.4 MPa, when temperature was raised from 4 ℃ to 65 ℃, the φ6, φ3 readings, yield point and plastic viscosity changed only slightly, which were 10-13, 9-12, 13-18 Pa and 15-22 m Pa· ·s, respectively, and the φ6 and φ3 readings showed "U" type pattern with temperature. At changing temperature/pressure combination, the correlation coefficients of the fitted empirical rheological equations are: Bingham model ≈ Casson model ≈ Herschel-Bulkley model ≈ Robertson-Stiff model, of which the bi-parametric Casson model has the highest correlation coefficient and simple expression and is therefore suitable for use in describing the consistent rheological properties of water base drilling fluid. Introduction of parameters into the Casson’s model gave birth to a kinetic rheological equation f(T, P, γ) with high precision of prediction; the average relative error is 7.19 % ± 4.07%, and the maximum deviation appears at 100(r/min)/65 ℃. In this paper, the molecular conformation, molecular structure and association with clay platelets of the key additives are analyzed, and the qualitative structure-activity relationship assumption based on molecular conformation is presented to reveal the essence of the consistent rheology of water base drilling fluids.更多还原