胍胶压裂液对阜东斜坡区头屯河地层的伤害

Study on the Formation Damage Mechanisms of Guanidine Gum Fracturing Fluid to Toutun River Formation of Fu Dong Slope Area

针对阜东斜坡区头屯河地层特低渗透砂砾岩岩心,通过流动试验系统评价了胍胶压裂液静滤失、动滤失以及破胶液对天然岩心、天然岩心粉末制备的填砂管渗透率的影响。岩心静滤失实验表明,胍胶压裂液滤液对阜东斜坡区头屯河地层岩心不产生伤害。在岩心动滤失过程中,胍胶压裂液在渗透率为9.61×10-3μm2的岩心端面会形成滤饼,对岩心的伤害率达到25%;但胍胶压裂液在渗透率为0.32×10-3μm2、46.20×10-3μm2的岩心端面几乎不会产生滤饼,岩心伤害率低于10%。该结果说明动滤失过程中滤饼的状态除与压裂液有关外,还取决于孔隙介质。此外研究发现,在水测渗透率为1300×10-3μm2填砂管中注入含有350 mg/L残渣的破胶液,渗透率下降达80%。

Based on the sandy conglomerate gravel core of extra-low permeability from Toutun River formation of Fudong slope area, the effects of static and dynamic filtration of guanidine gum fracturing fluids and broken fluid on permeability of the natural core and of the sand pack prepared with natural core powder were evaluated through flow test system. Core static filtration results showed that guanidine gum fracturing fluid filtration had little harm to the cores from Toutun River formation of Fudong slope area. During the core dynamic filtration process, guanidine gum fracturing fluid formed the filter cake on the end of the core with the permeability of 9.61 ×10-3 μm2 , thus leading to the core damage rate obtained to 25%. However, the filter cake hardly formed on the end of the cores with the permeability of 0.32× 10-3μm2 and 46.20× 10-3μm2, respectively, leading to the core damage rate was less than 10%. The results indicated that the state of the filter cake in the dynamic filtration process also depended on the porous medium besides fracturing fluid. In addition, it was found that the permeability reduces by 80% by injecting the broken fluid containing 350 mg/L residue into sand pack with a water permeability of 1300× 10-3μm2.The results will provide guidance on fracturing design in Toutun River formation of Fudong slope area.