聚乙烯醇(PVA)作为油井水泥降失水剂,适用温度较低(＜120℃),难以满足高温固的需求.以PVA1788、2-丙烯酰胺-2-甲基丙磺酸(AMPS)、N-乙烯基吡咯烷酮(NVP)和交联剂乙二醛等为原料,合成了一种油井水泥降失水剂接枝改性聚乙烯醇(PVA-1).室内试验评价了添加降失水剂PVA-1的水泥浆的耐温性能、流变性能、稠化性能、抗压强度和防气窜性能等.试验结果表明,加有降失水剂PVA-1的水泥浆API失水量可以控制在50 mL以下,抗温能力接近150℃;加有PVA-1的水泥浆稠化时间稍有延长,抗压强度不降低,抗析水能力增强;其与分散剂DZS和缓凝剂DZH的配伍性良好,还能提高水泥浆的防气窜能力.综合分析认为,合成的PVA-1能够满足150℃以下高温固井的需求.%As fluid loss additive for oil well cement, polyvinyl alcohol(PVA)is not suitable for formations above 120 ℃,a novel oil-well cement fluid loss additive(PVA-l),chemically cross-linked polyvinyl al-cohol(PVA)was synthesized from PVA,2-acrylamido-2-methyl propane sulfonic acid(AMPS),Nvinyl-2-pyrrolidone(NVP) ,and cross-linking agent. The properties(water-loss control property, rheology,thickening curve, thickening time,free water,compressive strength and static gelling strength)o￡ the cement slurry with PVA-1 were evaluated. The results show that the API fluid loss of the cement slurry with PVA-1 can be controlled under 50 mL,while its temperature tolerance is next to 150 ℃ ;the cement slurry with PVA-1 has slightly longer thickening time,no reduction in compressing strength and improved water precipitation resistance;moreover,the fluid loss additive (PVA-l)is highly compatible with dispersing agent DZS and retarder DZH.and can improve gas channeling of slurry. The study shows that PVA-1 can meet the requirements of high temperature cementation at nearly 150 ℃.
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