高强度堵水剂裂缝细管模型堵水模拟实验

在裂缝性致密储层中,裂缝既是油流通道又是水驱窜流通道,在注水开发中由于裂缝的存在导致水驱波及效率低,从而形成无效注水开发。此外,裂缝性储层的封堵又存在大裂缝封堵效果差、有效期短等问题。鉴于此研制了水溶性酚醛树脂冻胶和单体地层聚合高强度堵剂体系,测定了堵剂在70℃下的成胶性能、稳定性以及封堵强度等。通过细管模拟裂缝研究了不同因素对堵剂突破压力的影响;通过可视化细管研究了堵剂在管中的突破方式以及影响因素。研究结果表明,水溶性酚醛树脂冻胶的突破压力随着冻胶强度的增加而增加,随着管径的增加而减小,随着注水速度的增加先减小、后增加,最后稳定;单体地层聚合堵剂的突破压力随着堵剂强度的增加而增加,随着管径的增加先增大、后减小。在可视化细管实验中,堵剂突破时并不完全沿细管中心突破,其堵剂的强度与黏附性等因素有关。

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.