环保型β-环糊精聚合物微球高温降滤失作用机理

高温高压条件下钻井液滤失性的调控是保证钻井安全顺利的关键。针对传统降滤失剂环保性与高温降滤失性能难以兼顾的问题，以β-环糊精为单体，环氧氯丙烷为交联剂，通过反相乳液聚合法制备了环境友好的β-环糊精聚合物微球（β-CDP）。评价了不同温度热滚后的API滤失性能和高温高压滤失性能，并与几种典型的抗高温降滤失剂进行了性能对比，综合探讨了其滤失控制机理。研究表明，β-CDP在温度低于160℃时，降滤失性能优良；当温度超过160℃后，降滤失性能随着温度的升高进一步增强，240℃热滚后降滤失性能仍然突出，表现出与传统降滤失剂显著不同的特征。当温度低于160℃时，β-CDP主要通过吸水膨胀、增加泥饼压缩性、提高黏土分散稳定性等作用降低滤失量；当温度高于160℃时，β-CDP发生水热碳化反应，降解生成微纳米碳球以及与黏土颗粒相互作用生成纳米复合物，能够对泥饼的微纳米孔隙进行填充，有效降低泥饼的渗透性。β-CDP特有的这种"温度响应"特征，实现了将高温破坏处理剂的不利因素转变成滤失控制的有利条件。

Mechanism of filtration loss reduction of environment-friendly β-cyclodextrin polymer microspheres under high temperatures

To control the filtration of drilling fluid under high temperature and high pressure conditions is critical for ensuring the safe and successful drilling. Aiming at the problem that it is difficult to achieve a balance between the environmental protection property and the high temperature filtration performance for conventional filtration reducers, the environment-friendly β-cyclodextrin polymer (β-CDP)microspheres were synthesized with inverse emulsion polymerization method using β-cyclodextrin as the monomer and epichlorohydrin as the crosslinking agent. This paper evaluates the API filtration properties after hot rolling at various temperatures and high-temperature and high-pressure filtration properties after hot rolling at 200℃, which were compared with those of some typical high temperature resistant filtration reducers, and also systematically explores the underlying mechanism of filtration control. The research indicates that when the temperature is below 160℃, β-CDP microspheres exhibit excellent filtration control properties. When the temperature is above 160℃, the filtration control properties will be further improved with the increasing temperature. After hot rolling at 240℃, the microspheres still have prominent filtration control properties, and obviously different characteristics from conventional filtration reducers. When the temperature is below 160℃, the filtration loss is mainly reduced by swelling after water absorption, increasing the compressibility of filter cake, and improving the dispersion stability of clay particles by β-CDP microspheres. When the temperature is above 160℃, hydrothermal reaction occurs in β-CDP microspheres, thus producing micro-nano carbon spheres by degradation. Then, nano composites are formed through interaction of micro-nano carbon spheres and clay particles, which can fill in the micro-nano pores of filter cake and effectively reduce the permeability of filter cake. The temperature response behavior of β-CDP microspheres can change the disadvantage that additives are destroyed under high temperature into the favorable conditions for filtration control.