羟丙基淀粉的合成及其在钻井液中的应用

The composition of hydroxypropyl starch and its application in drilling fluid

以淀粉和环氧丙烷为原料,以碱为催化剂,采用溶剂法合成了取代度为0.5—0.8、具有冷水溶胀性的羟丙基淀粉。考察了用作钻井液降滤失剂的羟丙基淀粉的合成条件,并以羟丙基淀粉为主剂复配得到了QDF降滤失剂,测定了加入QDF后的钻井液性能。实验结果表明,当环氧丙垸与淀粉的物质的量比为0.6:1.0—1.0:1.、溶剂与淀粉的质量比为2.0:1.0—3.0:1.0、催化剂用量为淀粉质量的0.05％—0.1％、温度为90—110℃时,可以得到用作钻井液降滤失剂的羟丙基淀粉。QDF在淡水钻井液、4％盐水钻井液和饱和盐水钻井液中的加量为0.7％时,滤失量可分别由21.6、100.0和118.0 ml,下降到6.8、7.1和8.6 mL;当QDF加量为0.7％,CaCl_2加量为5％时,淡水钻井液和4％盐水钻井液的滤失量均小于8mL,QDF表现出了优良的降滤失性能和抗盐性能。

This paper proposes a method of synthesizing hydroxypropyl starch using starch and epoxypropane as crude materials, and alkali as accelerant. The synthesizing procedure of hydroxypropyl starch is described, and the synthetic hydroxypropyl starch is used to produce a fluid loss additive called QDF. QDF shows good fluid loss control and calcium contamination properties, and its usage in different kinds of drilling fluids are recommended based on tests results.