固井水泥浆共聚物类耐高温降失水剂的制备及其机理探究

Preparation and mechanism of high-temperature-resistant fluid loss additive of copolymer type for oil well cement

以2-丙烯酰胺-2-甲基丙磺酸(AMPS)、丙烯酰胺(AM)、丙烯酸(AA)、N-乙烯基吡咯烷酮(NVP)为单体,通过自由基共聚制备了降失水剂FLA。考察了适宜的合成条件,利用FTIR,1H NMR,GPC,TG-DTG对FLA的结构等进行了表征,并研究了含FLA的水泥浆性能。实验结果表明,合成FLA适宜的条件为:m(AMPS)∶m(AM)∶m(AA)∶m(NVP)=4∶3∶2∶1,反应温度50℃,pH=8,引发剂加量0.3%(w),反应时间4 h。FLA的添加降低了水泥浆的流变性能,但搭配分散剂时水泥浆的流变性能满足要求。FLA对水泥石的抗压强度无显著影响。含FLA的水泥浆具有较好的稠化性能。FLA加量为6%(w)的水泥浆在淡水中210℃下失水量小于60 mL,在18%(w)和36%(w)盐水中失水量小于100 mL。FLA各项性能均满足高温下固井技术要求。FLA可吸附在水泥颗粒表面,形成致密的吸附层,降低材料孔隙度,从而控制水泥浆过滤能力,有望应用于超深层油田固井工作中。

The fluid loss additive FLA was prepared by free radical copolymerization using 2-acrylamido-2-methylpropane sulfonic acid(AMPS),acrylamide(AM),acrylic acid(AA),and N-vinylpyrrolidone(NVP)as the monomers.The suitable synthesis conditions were investigated and the structure and other properties of FLA were characterized by FTIR,1H NMR,GPC,and TG-DTG and the properties of the cement paste containing FLA were studied.The experimental results show that the suitable conditions for synthesizing FLA are m(AMPS)∶m(AM)∶m(AA)∶m(NVP)=4∶3∶2∶1,reaction temperature 50℃,pH=8,initiator dosage 0.3%(w),reaction time 4 h.The addition of FLA reduces the rheological properties of the cement paste,but when combined with a dispersant,the rheological properties of the paste meet the requirements.FLA has no significant effect on the compressive strength of cement stone.The cement paste containing FLA has good thickening performance.The water loss of cement paste with FLA dosage of 6%(w)is less than 60 mL at 210℃in fresh water,and less than 100 mL in 18%(w)and 36%(w)brine.All the properties of FLA can meet the requirements of cementing technology under high temperature.The FLA can be adsorbed on the surface of cement particles to form a dense adsorption layer and reduce the porosity of the material,thus controlling the filtration capacity of the cement slurry,which is expected to be applied in the cementing work in ultra-deep oil fields.