可降解纤维压裂液性能评价

Performance evaluation of biodegradable fiber fracturing fluid

在瓜胶体系中加入合成的可降解两亲性聚酯类纤维,可以在降低稠化剂浓度的条件下,保证压裂液的携砂能力。研究纤维不同加量、不同长度对体系中支撑剂沉降速度的影响,发现对于给定流体黏度,质量分数为0.2%,长度为6 mm的纤维能使支撑剂沉降速度降为原来的1/3,携砂性能优异。有机硼交联0.3%瓜胶压裂液(HPG),加入过硫酸铵50 mg/L并在80℃放置5 h后,破胶残渣量为315 mg/L,而该体系加入0.2%可降解纤维DF-1后,破胶残渣量可减至160 mg/L;同时岩心伤害率也由17.45%降至12.31%;在70℃、170 s-1下剪切40 min,其黏度仍保持在70 m Pa·s以上,抗剪切性能良好,能够满足现场施工需求。

The addition of biodegradable fiber to guar gum fracturing fluid can both reduce the amount of thickening agent used and ensure the proppant carrying capability. The effects of the amount and length of fiber on the setting velocity of proppant are studied. The result shows that with a viscosity of the fluid, the settling velocity of proppant could be reduced to 1/3 of the original by addting 0. 2 wt% of the fiber with 6 mm of length, indicating the good proppant carrying capability. For an organo-boron crosslinked hydroxypropyl guar （HPG） fracturing fluid with introduction of 50 mg/L of ammonium persulfate and being placed at 80~C over 5 hours, the residue from gel breakdown is 315 mg. By contrast, the incorporation of 0. 2% of fiber DF-1 can lead to the decrease of residue to 160 mg/L. At the same time, the viscosity is still kept above 70 mPa-s after shearing at 70℃ for 40 minutes with shearing rate of 170 s -1 ,which indicates that this biodegradable fiber fracturing fluid has the great potential in sand fracturing jobs of medium scale.