水基钻井液用改性玉米淀粉降滤失剂的合成

Synthesis of Modified Maize Starch as Filtrate Loss Reducer for Water Base Drilling Fluid

以4％黏土淡水基浆50℃滤失量降低率为测定指标，用正交设计实验方法考察了制备醚化淀粉的工艺。特别是溶解NaOH用的水量和分散剂异丙醇的用量．最佳合成配方和条件如下：玉米淀粉8．1g，NaOH12g。水16mL，丝化温度40℃．丝化时间1．5h，氟乙酸11．5g，异丙醇180mL，醚化温度50℃，醚化时间3h。在该合成条件下制得的羧甲基淀粉在加量2％时降滤失率约46％，抗盐、抗钙性能较好，90～130℃抗温性测试结果表明具有一定抗温能力。 图2表4参5。

Taking percent filtrate loss reduction at 50℃ in a 4% clay base mud as the criterium in orthogonally designed experiments, the synthesis of an etherified starch and the amounts of water for dissolving NaOH and of dispersant isopropyl alcohol, in particular, are investigated and an optimal recept and conditions of synthesis are obtained： maize starch 8.1 g, NaOH 12 g, water 16 mL, and temperature and time of mercerization 40℃ and 1.5 h; chloroacetic acid 11.5 g, isopropyl alcohol 180 mL, and temperature and time of ethefificafion 50℃ and 3 h. The carboxymethyl starch synthesized gives about 46% filtrate loss reduction at dosage 2% and has fairly good salt and calcium tolerancy and a definite heat resistance as shown in a heat resistance test at 90-130℃.