聚苯乙烯中空微珠及其钻井液的研究

Research on Polystyrene Hollow Microsphere and Drilling fluid

赵素丽 陈 铖 石秉忠

ZHAO Su-Li CHEN Cheng SHI Bing-Zhong

利用乳液聚合法合成了球状聚苯乙烯中空微珠，表面致密光滑，壁厚均匀，密度可控制在0.2~0.6 g/cm3，粒径10~120 μm。选择粒径范围在20~60 μm、平均密度为0.50 g/cm3的聚苯乙烯中空微珠作为减轻剂。在0.2%黄原胶溶液中加入10%的聚苯乙烯中空微珠配制成低密度钻井液，初始密度0.92 g/cm3；90℃，在常压、0.3 MPa条件下热滚16 h后的密度分别为0.96、0.93 g/cm3。在温度增至90℃、压力增至50 MPa的过程中，聚苯乙烯中空微珠钻井液密度变化较小。10%聚苯乙烯中空微珠钻井液在12000 r/min下搅拌8 h后的密度为0.92 g/cm3，在固相研磨装置中滚动研磨8 h后的密度为0.93 g/cm3。剪切和研磨对聚苯乙烯中空微珠的影响小于玻璃中空微珠。在东北彰武3-2井进行了聚合物中空微珠在油田领域的首次现场试验，结果表明聚苯乙烯中空微珠具有降密度效果好，对钻井液性能影响不大的特点，但是存在易于团聚及与钻屑吸附而被固控设备筛出的问题。

Spherical polystyrene hollow microsphere was prepared by emulsion polymerization method. The surface of microsphere was compact and smooth and shell thickness was uniform. The density of the particle was 0.2—0.6 g/cm3 and the diameter was 10—120 μm. In laboratory research, microsphere which density of the particle in average was about 0.50 g/cm3 and the diameter was in range of 20—60 μm was chosen as light weight additive. Low-density (0.92 g/cm3) drilling fluid was prepared by adding 10% hollow polystyrene sphere to 0.2% xanthan gum solution. The density of drilling fluid changed to 0.96 or 0.93 g/cm3 when it was rolled 16 hrs at 90℃ and under constant pressure or 0.3 MPa. Drilling fluid’s density changed little when temperature rose to 90℃ and pressure rose to 50 MPa. Low-density drilling fluid’s density was 0.92 g/cm3 when it was stirred 8 hrs at a speed of 12000 r/min, and that was 0.93 g/cm3 when it was grinded 8 hrs, which indicated that the influence of stirring and grinding on hollow polystyrene sphere was smaller than that on hollow glass sphere. Hollow polystyrene sphere was applied in oilfield for the first time at Zhangwu area in northeast. The results showed that polystyrene sphere had little effect to drilling fluid and had a good ability to reduce drilling fluid’s density. But the sphere was easy to reunite together and adsorb to drillings, as a result, it was easy to be screened by solids control equipment.