抗高温弱凝胶提黏切剂WG-1的合成及评价

Synthesis and Evaluation of High Temperature Weak Gel Viscosifier WG-1

针对高温深井及特殊工艺井对钻井液的要求,采用反相乳液聚合方法研制了抗高温弱凝胶提黏切剂WG-1,考察了影响产品性能的关键因素,确定了最佳合成条件。由红外光谱图和扫描电子显微镜SEM可以看出,WG-1中含有AMPS、DMAM和NVP等基团,呈球状,粒径为0.1-1.8μm;浓度为1.0%的弱凝胶提黏切剂分散液经200℃老化16 h后,动塑比为0.47 Pa/mPa·s,满足200℃下的提黏度、切力要求;经170℃连续老化72 h后,表观黏度、动切力保持率较好,分别为60%和37%,能满足170℃下高温稳定性要求;且在淡水、饱和盐水钻井液中均具有较好的提黏度、切力能力和降滤失效果,170℃高温老化后,WG-1加量从0.5%增加到1.0%,淡水钻井液API滤失量由9.6 mL降低至4.8 mL;WG-1加量从1.0%增加到1.5%,饱和盐水钻井液API滤失量由8.8 mL降低至3.2 mL,说明研制的提黏切剂能够封堵微裂缝,改善滤饼质量,降低钻井液滤失量。

A high temperature weak gel viscosifier WG-1 has been developed using inverse emulsion polymerization in an effort to satisfy the needs for high temperature deep wells and non-conventional wells. The optimum synthesis conditions were determined and key factors affecting the performance of WG-1 examined. Groups such as AMPS, DMAM and NVP are found in the molecular structure of WG-1 through SEM observation, and these groups are in spherical forms, with diameters between 0.1 μm and 1.8 μm. These data demonstrate that WG-1 has good thermal stability, salinity tolerance and superior thickening and gelling capacity. A 1.0% WG-1 solution, after aging at 200 ℃ for 16 h, had YP/PV ratio of 0.47 Pa/mPa·s, suitable for use at that temperature as a viscosifier and gelling agent. WG-1 solution retained enough viscosity and gel strengths after aging for 72 h at 170 ℃, meaning that it suffices the needs for operation at 170 ℃.WG-1 can be used in both fresh water and saltwater drilling fluids as viscosifier and filter loss reducer. After aging at 170 ℃, the filtration rate of fresh water base drilling fluid was reduced from 9.6 mL to 4.8 mL, and that of saturated water base drilling reduced from 8.8 mL to 3.2 mL, indicating that WG-1 can plug micro fractures and improve the quality of mud cakes, thereby reduce the filtration rate.