The water shutoff simulation experiment using tube for high-strength plugging agent in fractured reservoir

In the fractured tight reservoir, fractures are the channels for oil flow, and also water transfer after water flooding. Fractures may result in low sweep efficiency during water flooding, thus leading to ineffective exploitation. Moreover, the sealing of fractured reservoirs may cause many problems, such as poor sealing effect for large fractures and short-term durability. Aiming to solve those difficulties, two types of water-shutoff plugging systems have been developed:water-soluble phenol-formaldehyde resin gel and monomer polymerization breakthrough pressure plugging agent. On this basis, the authors determine the gelation performance, stability and strength of plugging agents at 70℃. Then the effects of various factors on the breakthrough pressure of water-shutoff agent have been studied by fracture simulation using a tube. The breakthrough direction of plugging agent and the influencing factors has been explored by experiments performed in a visible tube. The results show that the breakthrough pressure of water-soluble phenol-formaldehyde gel increases with the increasing of gel strength, and decreases with the increasing of tube diameter; it decreases first and then increases with the raising of water injection speed, and finally stabilizes. As for the monomer polymerization plugging agent, the breakthrough pressure increases with the increasing strength of plugging agent; it increases first and then decrease with the increasing of tube diameter. In the tube visualization experiments, the plugging agent did not break through only along the center of tube, which was related with the strength and adhesion of plugging agent. © 2019, Editorial Office of ACTA PETROLEI SINICA. All right reserved.