耐温抗盐型聚合物微球凝胶体系的制备及性能评价

Preparation and Performance Evaluation of Gel Based on Polymer Microspheres

为满足带压作业对凝胶强度、成胶时间可控、热稳定性、耐盐性、承压能力的性能要求,拟将聚合物微球引入到凝胶体系中:先制备丙烯酰胺/2-丙烯酰胺-2-甲基丙磺酸(AMPS)、共聚物微球,以玉米淀粉做骨架与共聚物微球接枝共聚,调节pH值为8~9,加入自制交联剂MES、高温引发剂G20制备一种耐温抗盐型聚合物凝胶。获得了制备共聚物微球的最佳配比,考察了交联剂MES、pH值对凝胶体系成胶性能的影响,采用SEM扫描电镜测试分析了凝胶微观结构,并对凝胶热稳定性、抗盐性、高温稠化性能和承压性能进行性能评价。研究结果表明,配方为2.5%淀粉+15%聚合物微球+6%交联剂MES+0.005%引发剂G20的凝胶在90℃高温稠化条件下的成胶时间可控在1.5 h左右,且稠化过渡时间较短,可有效降低凝胶溶液在井筒内成胶过程中液窜/气窜的可能;在90~130℃范围内,凝胶强度可达28 N,在10 d长期高温养护下,凝胶强度变化较小,呈现出较好的热稳定性;使用盐加量为9~18 g/L的高矿化度水溶液制备的凝胶体系成胶性能优良,体现出较好的耐盐性,可有效克服井下矿化度影响;凝胶在内径为121 mm套管内承压强度达70 kPa/m,满足高压条件下带压作业需求。

In order to meet the performance requirement of pressure operation to the gel strength,controllable gelation time,thermal stability,salt resistance and pressure bearing capacity,the polymer microspheres was introduced to the gel.With acrylamide as the main component,2-acrylamide 2-methylpropanesulfonic acid(AMPS),surfactant SDBS and initiator G20 were introduced to make copolymer microspheres.Corn starch was used as the skeleton and copolymer microspheres were grafted and copolymerized.The pH value was adjusted to 8-9.The optimum ratio of copolymer microspheres was obtained,the influence of cross-linking agent MES and pH value on the gel formation performance was investigated,the microstructure of the gel was analyzed by scanning electron microscopy,and the thermal stability,salt resistance,high temperature thickening and pressure bearing performance of the gel were evaluated.The results showed that under the condition of 90℃high temperature thickening,the gelling time of the gel system,composed of 2.5%starch+15%polymer microspheres+6%cross-linking agent MES+0.005%initiator G20 gel,could be controlled within around 1.5 h,moreover,the thickening transition time was shorter,which effectively reduced the possibility of gel/gas channeling in the gelling process of the gel solution in the wellbore.Within the temperature range of 90-130℃,the gel strength was up to 28 N and could be stable for 10 days.The gel system prepared with high-salinity aqueous solution with a salt concentration of 9-18 g/L had excellent gel forming performance,showing good salinity resistance,and could effectively overcome the influence of salinity underground.The capacity of pressure bearing of the gel in the case with inner diameter of 121 mm was up to 70 kPa/m,which met the requirements of high-pressure operation.