水基钻井液用碳酸钙微米颗粒的分散状况

为了研究水基钻井液用碳酸钙微米颗粒在水溶液中的分散状况,使用扫描电镜对碳酸钙微米颗粒的微观形貌进行了分析,而后在不同搅拌速度、不同p H、不同超声时间等物理分散因素下研究了碳酸钙微米颗粒在水溶液中的粒径分布与Zeta电位变化,又利用不同的分散剂对碳酸钙微米颗粒进行了化学分散.结果表明:长期放置的碳酸钙微米颗粒会发生团聚,中径达6~7μm;采用物理方法分散时,搅拌速度越高,分散效果越好,在10 000 r/min时可使中径达3~4μm;超声作用则使碳酸钙微米颗粒粒径先减小后增大,中径最小可达2.6μm,p H小于10时,粒径随p H的增大而增大,大于10时则随p H的增大而减小;化学分散剂对提高碳酸钙微米颗粒的分散具有显著的作用,其中,无机类分散剂六偏磷酸钠可使碳酸钙微米粒子中径达到1.5μm,并且Zeta电位绝对值显著提高.

Aqueous dispersion of calcium carbonate microparticles for water-based drilling fluids

To study water?based drilling fluids with calcium carbonate microparticles in aqueous dispersion conditions, the micro morphology of calcium carbonate microparticles was analyzed by scanning electron microscope ( SEM) . Then, the paper studied the particle size distribution of calcium carbonate microparticles in water solution and the variation of Zeta potential were studied based on researches on several physical dispersion factors, including different stirring rate, different pH, and different ultrasonic time. Finally, chemical decomposition for calcium carbonate microparticles with various dispersants were carried out. Experimental results show that placement of microparticles calcium carbonate material for a long time will reunite and its diameter reaches 6~7 μm. Using physical dispersion, the higher the stirring speed, the better the dispersion effects. When stirring speed is 10 000 r/min, the diameter can reach 3~4 μm. Ultrasound causes the particle size of calcium decreasing first and then increasing. The minimum medium diameter is 2.6μm. When the value of pH is less than the number 10, particle size increases with the increase of pH. When the value of pH is more than number 10, particle size decreases with the increasing of pH value. Chemical dispersants play an important role in improving the dispersion of calcium carbonate microparticles. The inorganic dispersant, sodium hexametaphosphate ( SHMP ) can make diameters of calcium carbonate nanoparticles reach 1.5 μm andincrease the absolute value of the Zeta potential remarkably.