龙26外扩致密油试验区压裂液损害评价及其微观机理

大庆龙26外扩试验区为典型致密储层，对压裂液损害更为敏感。依据SY/T 5107—2005《水基压裂液性能评价方法》在储层温度(90 ℃)下采用岩心流动装置进行了胍胶、化学高分子聚合物和表面活性剂压裂液破胶液的岩心驱替实验；结合CT扫描评价了3种压裂液破胶液残渣、残胶在岩心中的分布和对孔隙孔喉的损害程度。岩心驱替实验结果表明，胍胶、化学高分子聚合物和表面活性剂3种压裂液破胶液对岩心损害率分别为43.5%、24.3%和13.1%。CT扫描结果显示，胍胶和化学高分子聚合物压裂液破胶液残留物分别集中于岩心前1/10～2/5段和前1/2段，表面活性剂压裂液破胶液残渣含量少，但能侵入岩心各处；胍胶、化学高分子聚合物和表面活性剂压裂液破胶液对储层岩心孔隙和孔喉的损害率分别为15.41%和9.01%，6.43%和3.14%，8.94%和6.27%。分析认为，3种压裂液破胶液对储层岩心均以液相损害为主，固相损害次之。 

Fracturing Fluid Damage Evaluation and Microscopic Damage Mechanism Study for Expansion Tight oil Test Area of Long 26

Extension area of long 26 in Daqing oilfield is typical tight reservoir, which is more sensitive to fracturing fluid damage. According to ‘SY/T 5107-2005 Recommended practices on measuring the properties of water-based fracturing fluid’, the core displacement experiments of guar gum, high molecular polymer and surfactant fracturing gel-breaking fluids were conducted at reservoir temperature (90 ℃) with core flow meter, and the distribution of residue and residual gum of the three fracturing gel-breaking fluids in the cores and their damage degree to pore throats were evaluated with CT scanning. The results of core displacement experiments indicated that the core damage rates of guar gum, high molecular polymer and surfactant fracturing gel-breaking fluids were 43.5%, 24.3% and 13.1% respectively. The results of CT scanning showed that residues of guar gum and high molecular polymer fracturing gel-breaking fluids were concentrated in the first 1/10~2/5 and 1/2 sections of the core respectively, and the residues of surfactant fracturing gel-breaking fluid were less but penetrated into the core. The pore and the pore throat damage rates on cores of guar gum , high molecular polymer and surfactant fracturing gel-breaking fluids were 15.41% and 9.01%, 6.43% and 3.14%, 8.94% and 6.27% respectively. The analysis showed that the three kinds of fracturing gel-breaking fluids on reservoir cores were mainly liquid damage, followed by solid damage.