摘要
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10 min，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120 min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1000 mg/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。
Abstract
The gravel fill sand control technology of viscosity steady acidizing fluid was researched in view of the problem that the conventional acid treating had easily caused reservoir sand production and immediate vicinity of wellbore blocking. The formula of the NWS-Ⅰacidizing fluid system was obtained as follows: 6% HCl, 3% ZNW, 0.1% HPAM, 0.05% aluminium citrate (YL-1), 1% ammonium chloride, 1% ion stabilizers, 1% XP inhibiter, 0.5% CF-5B cleanup additive. After the core was treated by viscosity steady acidizing fluid, the dissolution rate of core decreased from 1.58% to 0.55%. The exit pH value was about 4.7, and the effective distance was more than 2.0 m. The subsidence time of gravel in viscosity steady acidizing fluid was longer than 10 min. The sand mixed uniformly, subsidence velocity was homogeneous. The retention rate of viscosity was up to 83.3%, 68.7% and 59.7% respectively, when the acidizing fluid was sheared at 30, 60 and 80℃ with 120 min, which had a good rheological behavior. When the concentration of acidizing fluid increased from 200 to 1000 mg/L, the damage rate of core increased from 0.6 to 1.27, which had little damage to formation. Compared with mud acid, viscosity steady acidizing system could restrain second sediment better. Field test in Shengli oilfield indicated that the productivity of five test wells increased 1.54times, construction success rate was 100% and valid period was long.
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