摘要
万城油田新沟嘴组储层是典型的浅层低压低孔低渗储层，优选出适合重复压裂改造的携砂能力强、易破胶返排、储层伤害小的压裂液体系是确保施工成功和提高压后效果的关键。经室内实验优选得到0.50%稠化剂HPG、0.50%助排剂BA1-5、0.50%黏土稳定剂BA1-13、0.20%杀菌剂BA2-3、0.45%（交联比）交联剂（BA1-21A、BA1-21B质量比10:1）组成的低伤害压裂液体系。压裂液性能评价实验表明：该体系在70℃、170 s-1下剪切2 h后的压裂液黏度约120 mPa·s，抗剪切性较好；破胶剂(NH3)2S2O8加量在500 mg/L时，压裂液在2 h内彻底破胶，破胶液黏度为3 mPa·s，破胶性能良好；压裂液体系破胶后的地层支撑裂缝导流能力约116.68 D·cm，伤害率为28%，对储层伤害小。该体系在W5X井成功进行了现场试验，施工平均砂比29.3%，排量4.5~5.0 m3/min；重复压裂效果理想，压后稳定日产液6.5 t，日产油5.1 t。
Abstract
Xingouzui formation was typical low pressure, low porosity, low permeability and shallow buried reservoir in Wancheng oilfield. To re-treatment successfully and improve postfracture response in the formation, it was critical to select the fracturing fluid system for refracturing, which could be provided with proppant carrying capacity enough, broken and flowbacked easily and low reservoir damage. According to the research in laboratory, a special kind of low damage refracturing fluid system including 0.50% gelling agent HPG, 0.50% cleanup additive BA1-5, 0.50% clay inhibitor BA1-13, 0.20% bactericidal agent BA2-3 and 0.45% crosslinker BA1-21A and BA1-21B (10%—30% NaOH solution) in mass ratio 10:1 was developed successfully. Fracturing fluid evaluating experiment results showed that this system was characterized by excellent anti-shearing performance, as the viscosity of fracturing fluid gel still kept about 120 mPa·s after shearing 2 hrs at 70℃ and 170 s-1, good gel breaking property, as the viscosity of broken-gel fluid was 3 mPa·s with (NH4)2S2O8 dosage of 500 mg/L, and little damage to the formation, as the formation fracture conductivity was about 116.68 D·cm with the fracture conductivity damage rate about 28% after system breaking. The fracturing fluid system was used to retreatment in W5X well successfully, with 29.3% proppant concentration in average and 4.5~5.0 m3/min construction displacement. The postfracture response was desired whose stable daily fluid production rate was 6.5 t and daily oil production was 5.1 t.
论文详情