聚丙烯酰胺类交联酸破胶新方法

聚丙烯酰胺类交联酸已广泛应用于高温深井地层酸压改造中，提高其破胶效率有利于降低地层伤害和提高增产效果。通过室内试验分析了交联酸中酸的加量、温度以及破胶剂加量对交联酸破胶效果的影响，利用螯合剂络合金属离子方法，对交联酸破胶效果进行了优化。结果表明，当温度小于60 ℃、酸的加量大于15%时，交联酸的黏度大于400 mPa·s，不发生破胶；当交联酸中酸的加量为20%时，过硫酸铵加量由0.1%增至0.6%对破胶效果影响不大；温度为90 ℃时，交联酸的黏度在10 min后降至5 mPa·s，残渣含量1 470 mg/L，破胶不均匀。对比不同破胶方式下的破胶效果可知，交联酸中加入0.1%EDTA和0.1%胶囊破胶剂，60 min后其黏度降至8 mPa·s，残渣含量387 mg/L，破胶效果好。这表明，应用胶囊破胶剂和EDTA（螯合剂）的组合破胶方式，可延缓破胶剂有效成分的释放速度和降低交联酸的黏度，达到改善交联酸破胶效果的目的。 

New Method of Polyacrylamide Crosslinked Acid Gel-Breaking

Polyacrylamide crosslinked acid has been widely used in the acid fracturing in deep high temperture wells.The gel-breaking is to reduce the strata damage and to improve the effects of stimulation.Through laboratory tests,acid amount,temperature and gel breaker amount were analyzed for their effects on crosslinked acid gel breaking.Using the method of complexing metal ion in chelating agent,the crosslinked acid gel breaking effect was optimized.The results showed that no gel breaking occurred when temperature was less than 60 ℃,the acid amount was greater than 15%,and crosslinked acid viscosity was higher than 400 mPa·s;gel-breaking performance was not affected significantly when the acid amount was 20% and the mass fraction of ammonium persulfate increased from 0.1% to 0.6%,gel-breaking was uneven when the temperature was 90 ℃,crosslinked acid viscosity dropped to 5 mPa·s after 10 min,and the residue content was 1,470 mg/L.It indicated that the viscosity of crosslinked acid fell to 8 mPa·s after 60 min when 0.1% EDTA and 0.1% capsule breaker were added and the residue content was 387 mg/L,which led to improved gel breaking effect.The results showed that the combination of capsule breaker and EDTA(chelating agent)in the crosslinked acid system could delay the release rate of effective components in the gel-breaker and reduce the crosslinked acid viscosity,and finally improve effect of crosslinked acid gel-breaking.