Influence of organoboron cross-linker and reservoir characteristics on filtration and reservoir residual of guar gum fracturing fluid in low-permeability shale gas reservoirs

To effectively reduce the filtration rate of water-based fracturing fluid and promote the pressure holding effect of fracturing fluid in underground unconventional reservoirs, an efficient and clean organic-boron cross-linker was synthesized with boric acid and low alcohols. The results obtained that the synthesized organoboron cross-linker exhibits better fluid loss performance to water-based fracturing fluid than the commercially available cross-linker. This organoboron cross-linker allowed decreasing filtration coefficient more than 0.74 × 10 –2 m 3 ·min 1/2 as a result of the network structure formed by the organoboron cross-linker and guar gum molecule. However, commercially available cross-linker exhibits a relatively large filtered mass of water more than 1.33 × 10 –2 m 3 ·min 1/2 at the same condition. Meanwhile, the cross-linked guar gum fracturing fluid can significantly improve the fluid loss property with the increase of cross-linker content and pressure, and an increased fluid filtration gradually was revealed with increasing the reservoir temperature and current speed. Moreover, the damage of shale reservoir caused by the prepared boron cross-linker was only 11%, which was lower than 18% of the commercial boron cross-linker under the same conditions.