高温海水基压裂液稠化剂两性离子胍胶合成及性能评价

Synthesis and Performance Evaluation of Zwitterion Guar for High Temperature Seawater Base Fracturing Fluid

为满足使用海水配制高温海水基压裂液的需要,以胍胶和(2-羟基-3-氯)-丙基二甲氨基乙酸为原料,合成了高温海水基压裂液稠化剂两性离子胍胶HDPG——2-羟基-3-(N,N-二甲基甘氨酸基)丙基胍胶,研究了醚化剂用量、氢氧化钠用量、醚化反应温度、醚化反应时间对该两性离子胍胶取代度的影响,考察了HDPG压裂液的溶胀性能、耐温耐剪切性能和破胶性能。确定了最佳反应条件为:醚化剂、胍胶质量比0.18∶1,氢氧化钠、胍胶质量比0.125∶1,醚化反应温度70℃,醚化反应时间6 h,最佳反应条件下产物取代度为0.43。研究结果表明:在转速500 r/min下,质量分数0.5%的HDPG在溶胀10 min时的黏度达到最终黏度的85%,可满足连续混配要求;与自制交联剂制备的海水基压裂液冻胶具有良好的耐温抗剪切性能,在温度170℃、剪切速率170 s-1下剪切120 min后的黏度在50 mPa·s以上。此外,HDPG压裂液的破胶性能良好,破胶液黏度(1.36 mPa·s)低、残渣含量(326 mg/L)低。

Zwitterion guar 2-hydroxyl-3-（N,N-dimethylglycine）propyl guar gum（HDPG）as high temperature thickener,used for seawater based fracturing fluid,was synthesized from guar and（2-hydroxy-3-chloride）-propyl dimethylamino acetic acid. The effect of dosage of etherifying agent,sodium hydroxide and etherification temperature,etherification time on the substitution degree was studied,and the swelling property,shear resistance property,and break character of HDPG were researched. The optimum reaction condition of thickener was obtained as follows,molar ratio of etherifying agent to guar was 0.18∶1,molar ratio NaOH to guar was 0.125∶1,the etherification temperature was 70℃,the etherification time was 6 hours,the substitution degree of HDPG was0.43. On the condition of stirring rate of 500 r/min and the swelling time of 10 min,the viscosity of 0.5% HDPG solution reached85% of final viscosity,which met the requirement of continuous mixing. The viscosity of seawater base fracturing fluid prepared by synthesized thickener and self-made crosslinking agent was above 50 mPa·s at the temperate of 170℃ after sheared for 120 min at the shearing rate of 170 s-1,which indicated that the seawater based fracturing fluid had good shear resistance. In addition,HDPG seawater base fracturing fluid had good gel-breaking performance,the viscosity of gel breaking liquid being of 1.36 mPa·s,and the residue content being of 326 mg/L.