恒流变合成基钻井液关键机理研究

以FLAT-PRO恒流变体系核心处理剂流型调节剂酰胺化二聚酸衍生物和有机蒙脱土为研究对象，通过宏观、微观和流变分析相结合，深入研究了恒流变合成基钻井液的恒流变性机理。控温流变实验和静置实验表明，低温下，油相体积压缩，有机土在油中的分散性变差，体系黏度切力大幅提高。随着温度升高，油相体积膨胀，有机土扩散性增强，体系黏度切力减小。加入流型调节剂后，钻井液的黏度切力随温度变化减缓，表现出了恒流变特性。显微镜观察，X射线衍射分析、扫描电镜观察结果表明，流型调节剂分子可以插入有机蒙脱土层间，扩大层间距并促进其片层在油中高度分散。最终在钻井液体系中由高度分散的有机土片层、流型调节剂分子和乳液滴共同构成了具备温度响应性的致密网络结构。流型调节剂分子链随温度升高而舒展，导致与2℃相比，体系黏度切力在65℃下增幅更大，从而使流变性在2～65℃范围内随温度变化更加平缓，形成恒流变性能。

Study on Key Mechanisms of Constant Rheology Synthetic Base Drilling Fluids

An amidated dimer acid derivative (a flow-pattern optimizer) and organophilic montmorillonite are two core additives used in formulating the FLAT-PRO constant rheology fluid. By studying these two additives from macroscopic and microscopic perspective and rheological analyses, the constant rheology mechanisms of the FLAT-PRO fluid was extensively investigated. Rheological experiment under controlled temperatures and long-time standing test results showed that, at low temperatures, the volume of the oil phase is reduced, the dispersibility of the organophilic clay in the oil phase becomes poor, and the viscosity and gel strengths were increased greatly. With temperature increasing, the volume of the oil phase expands and the organophilic clay becomes well dispersed in the oil phase, the viscosity and gel strength of the drilling fluid were correspondingly reduced. When the flow-pattern optimizer was added into the drilling fluid, changing of the viscosity and gel strength of the drilling fluid with temperature becomes less progressive, and the drilling fluid thus showed to some extent a constant rheology characteristics. Microscope observation, XRD analysis and SEM observation showed that the molecules of the flow-pattern optimizer can intercalate in between the micro crystal layers of the organophilic montmorillonite, thereby increasing the c-space of the clay and improving the dispersion of the clay in oil. In this way a temperature-responsive tight network structure is formed in a drilling fluid by highly dispersed clay platelets, molecules of the flow-pattern optimizer and emulsified droplets. The molecular chains of the flow-pattern optimizer become stretched at elevated temperatures; compared with the viscosity and gel strength of the drilling fluid at 2 ℃, the viscosity and gel strength of the drilling fluid at 65 ℃ were increased with much higher magnitude, making the rheology of the drilling fluid change more gently between 2 ℃ and 65 ℃, showing a characteristics of constant rheology.