抗高温反相乳液增黏剂DVZ-1的研究与应用

摘要

针对新疆塔东地区深井高温下导致钻井液流变性变差等问题,采用氧化还原体系,利用反相乳液聚合法,以白油为油相,以2-丙烯酰胺基-2-甲基丙磺酸(AMPS)、N,N-二甲基丙烯酰胺(DMAM)和N-乙烯基吡咯烷酮(NVP)为原料,合成了抗高温钻井液用增黏剂DVZ-1.研究了单体配比、引发剂和反应温度等条件对产品性能的影响,并借助于红外光谱、热重分析及凝胶色谱仪对合成产物进行了表征,评价了该产品在钻井液中的增黏性、高温稳定性和降滤失性,并分析了其作用机理.结果表明,DVZ-1的最佳合成条件为单体质量分数为50%(相对于水相),引发剂用量为0.2%,油水比为1:1,复合乳化剂质量分数为7%(相对于油相),单体物质的量比为AMPS:DMAM:NVP=1:4:0.5,pH值为8,反应温度为50℃,反应时间为6 h,合成的DVZ-1热稳定性好,抗温达220℃,在淡水、盐水和饱和盐水基浆中均有较好的增黏和降滤失作用,在塔东GC14井和大庆XS7-H1井等6口井的现场应用过程中,解决了钻井液高温减稠、窄环空间隙条件下携岩等问题,保障了钻井作业的顺利实施.%A high temperature inverse emulsion viscosifier DVZ-1 has been developed to resolve the mud rheology deterioration at elevated temperatures in deep wells drilled in the east Tarim area, Xinjiang. DVZ-1 was synthesized with AMPS, DMAM and NVP through inverse emulsion polymerization (a redox system), with white oil as the oil phase. The optimum ratio of the monomers, initiator and reaction temperature for the polymerization were studied, and the synthesized product was characterized with IR spectroscopy, thermogravimetric analysis and gel chromatography. The viscosifying performance, high temperature stability and filtration control ability of DVZ-1 were evaluated, and the working mechanisms of DVZ-1 analyzed through laboratory experiments. The optimum polymerization conditions were as follows: monomers' mass fraction = 50% (based on the mass of the water phase), concentration of the initiator = 0.2%, oil/water ratio = 11, mass fraction of the compound emulsifier = 7% (based on the mass of the oil phase), molar ratio of the monomers wasAMPS:DMAM:NVP = 1:4:0.5, pH = 8, reaction temperature = 50 ℃, and reaction time = 6 h. DVZ-1 has good thermal stability, and properly functions at 220 ℃. DVZ-1 is a good viscosifier and a good filter loss reducer in fresh water, saltwater and saturated drilling fluids. It has been used successfully on 6 wells, such as the well GC14 (east Tarim, Xinjiang) and the well XS7-H1 (Daqing oilfield). Problems such as mud thinning at elevated temperatures and difficulties in cuttings carrying through narrow annulus were resolved, ensuring the success of the drilling operation.