Maleic anhydride-acrylic acid copolymer (MAA) was synthesized with maleic anhydride (MA) and acrylic acid (AA) by the free radical water solution polymerization in which AA was supplemented in batches. The effect of MAA on the viscosity of drilling fluid was evaluated. The following are the best synthesized conditions of the viscosity reducer;the initiator amount is 0. 6, the acrylic acid and maleic anhydride monomer molar ratio is 1. 5 : 1, dropping time is 90 min, the polymerization temperature is 80℃, and polymerization time is 120 min. MAA could reduce viscosity and shearing force of drilling fluids. When the addition of viscosity-reducer is 0.6% , the thinning rate at high temperature will be up to 94. 8% for fresh water clay mud. It has very good resistant performance to temperature,salt and calcium. It can resist temperature of 180℃, be used in saturation salt solution and is stable in 2% calcareous base mud.%以马来酸酐(MA)和丙烯酸(AA)为原料,采用活泼单体滴加方式,通过水溶液自由基共聚合反应制备二元共聚物(MAA),评价MAA对钻井液黏度的影响.结果表明:MAA的最佳合成条件是引发剂用量0.6、丙烯酸与马来酸酐单体摩尔比1.5∶1、滴加时间90 min、聚合温度80℃,聚合时间120 min; MAA可以显著降低钻井液的黏度和切力,加入0.6％降黏剂的淡水基浆,高温降黏率可以达到94.8％;MAA具有很好的抗温、抗盐和抗钙性能,抗温达180℃,抗盐可达饱和,在2％的含钙钻井液中仍有较好的降黏效果.
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