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针对高泥质疏松砂岩油藏开发中后期,常规酸化易导致储层出砂加剧和近井地带堵塞等问题,开展了黏稳酸砾石充填防砂工艺技术研究,研发了具有解堵、携砂、稳砂等功能的NWS-I型黏稳酸体系:6%HCl+3%ZNW+0.1%非离子聚丙烯酰胺+0.05%柠檬酸铝YL-1+1%防膨剂+1%铁离子稳定剂+1%XP缓蚀剂+0.5%CF-5B助排剂。岩心经黏稳酸处理后,失重率由1.58%降至0.55%,出口处pH值≥4.7,有效作用距离在2.0 m以上。砾石在黏稳酸中完全沉降所用时间大于10min,混砂均匀,沉降速度均一,悬砂性能良好。黏稳酸在30、60、80℃下剪切120min后的黏度保留率分别可达83.3%、68.7%、59.7%,流变性较好。黏稳酸浓度从200增至1000mg/L时,岩心伤害率从0.6逐渐增至1.27。与土酸相比,该体系抑制二次沉淀的能力强。胜利油田现场5口试验井施工后,产能提高了1.54倍,施工成功率100%,有效期长。
In the middle and later stages of the development of high-shale unconsolidated sandstone reservoirs, the conventional acidification easily leads to the exacerbation of sand production in the reservoir and the blockage in the near-wellbeds. The research on sand-grading technology of viscous gravel packs has been carried out. Stabilized sand and other functions of the NWS-I type of viscous acid system: 6% HCl +3% ZNW + 0.1% non-ionic polyacrylamide + 0.05% aluminum citrate YL-1 + 1% anti-swelling agent + 1% Agent + 1% XP corrosion inhibitor + 0.5% CF-5B drainage aid. After the core was treated by the viscous acid, the rate of weight loss decreased from 1.58% to 0.55%, the pH at the outlet was ≥4.7 and the effective distance was above 2.0 m. Gravel completely settled in the viscous acid in the time spent more than 10min, uniform sand, sedimentation rate uniform, suspended sand performance is good. Viscosity retention rates of viscous acid at 83, 60 and 80 ℃ for 120 min were 83.3%, 68.7% and 59.7%, respectively. The rheological properties were better. Viscous acid concentration increased from 200 to 1000mg / L, the core injury rate gradually increased from 0.6 to 1.27. Compared with the soil acid, the system has the ability to inhibit secondary precipitation. After the construction of 5 test wells in Shengli Oil Field, the production capacity has increased by 1.54 times and the construction success rate has reached 100% with a long validity period.