Optimization and Application of Bio-Enzyme-Enhanced Gel-Breaking Technology in Fracturing Fluids for Tight Sandstone Gas in the Linxing Block, Ordos Basin

The main tight sandstone gas reservoirs in the Linxing block of the Ordos Basin exhibit a temperature range of 35–60 °C. Under these low-temperature conditions, conventional oxidative gum breakers used in fracturing operations react sluggishly, fail to break the gum completely, and can cause significant reservoir damage. In order to achieve complete breakage of the fracturing fluid and reduce the damage to the fracture and reservoir, active bio-enzyme-enhanced breakers have been incorporated into fracturing fluid formulations, so as to achieve rapid breakage, re-discharge at low temperature, and reduce the contact time between the fracturing fluid and the formation, which is critical for enhancing production efficiency. Based on the preliminary success of bio-enzyme-enhanced fracturing technology, this paper carries out an optimization study of bio-enzyme-enhanced fracturing technology for the low-temperature reservoir in the Ordos Linxing block. The study simulates the temperature recovery of the injected fluids under different reservoir temperatures during the fracturing process, aiming to further optimize the concentration of the bio-enzyme-enhanced fracture breakers in the fracturing phases, and to achieve optimized fracturing technology which is more in line with the temperature environment of the fluids. This can further optimize the concentration of the bio-enzyme breaker added at each fracturing stage, and achieve enhanced breaking in a stepwise manner that is more in line with the fluid temperature environment, thus improving the efficiency and production capacity for subsequent production. The optimized fracturing fluid system, incorporating the tailored concentration of the bio-enzyme breaker, was applied to 54 wells in this block, resulting in about a two-times improvement in production compared to conventional non-optimized methods, with many wells achieving high output. These results demonstrate the strong applicability of the optimized breaker procedure in this geological context. Additionally, this study investigated an optimization model for the well shut-in time during winter operations involving low-temperature fracturing fluids in low-temperature reservoirs, providing a valuable design basis for future production planning.