Stretchable, compressible, and thermo-responsive hydrogel for hot work in oil pipelines

Hydrogels can temporarily plug oil pipelines, ensuring the safety of hot work. However, hydrogels are prone to fragmentation during the injection, and the chemical hydrogels are often difficult to completely remove from the oil pipeline. Herein, we prepared a stretchable, compressible, and thermo-responsive hydrogel through the 6-aminouracil-modified copolymerization of acrylamide acrylic acid (AUP) with melamine (MEL). The rheological results indicate the hydrogel exhibits tunable mechanical strength and self-recovery. The maximum tensile strength and elongation of the hydrogel containing 25 g/L MEL are 5.19 kPa and 237.6 %, respectively. Moreover, the tensile Young's modulus and the toughness of the hydrogel are measured at 3.30 kPa and 7.07 kJ/m³, respectively. The thermo-responsive properties of the hydrogel indicate that they can easily dissolve due to the hydrogen bonds. The hydrogel demonstrates exceptional flame-retardant properties, ensuring the safety of hot work. When the plugging length of hydrogel in the simulated pipeline reached 50 cm, the maximum resistance pressure was 117.3 kPa, indicating an effective plugging capability. Furthermore, the hydrogel injected into the oil-coated pipeline can displace the residual oil, significantly reducing the residual oil content in the plugging area, thereby further ensuring the safety of hot work. The hydrogel with a plugging length of 20 cm was completely removed in approximately 40 min with 70 °C hot water. The stretchable, compressible, and thermo-responsive hydrogel can effectively plug oil pipelines and can be rapidly removed by injecting hot water, thereby ensuring the implementation of hot work and enhancing the efficiency of pipeline repair and replacement.