Abstract:

Polymer flooding is an important enhanced oil recovery (EOR) technology, which has achieved significant effects in major oilfields in China. However, long-term polymer flooding has led to increased reservoir permeability difference and polymer plugging. After polymer flooding, a series of development problems such as inefficient circulation of injected media, high injection pressure, and highly dispersed residual oil are commonly encountered in old oilfields. The existing EOR technology cannot effectively use the residual oil in the reservoirs after polymer flooding. Therefore, this paper systematically investigated and analyzed the existing EOR technology in reservoirs after polymer flooding and identified the key technical problems that need to be overcome to further improve the EOR of old oilfields after polymer flooding. The paper proposed that the EOR after polymer flooding can be greatly improved by using the safe and environment-friendly nonoxidizing plugging remover to remove the polymer plugging in the reservoir, adopting “plugging but keeping certain permeability” deep profile control technology to control the flow direction of deep liquid, and subsequently injecting new nano fluid with automatic oil finding and efficient washing functions, which can be a technical direction.

Key words: enhanced oil recovery after polymer flooding, safe unplugging, “plugging but keeping certain permeability” profile control, nano-fluid displacement

摘要：

聚合物驱是一项重要的提高采收率技术，在中国各大油田开发应用中取得了显著的效果。但长期的聚合物驱导致储层渗透率级差加大和聚合物堵塞，聚合物驱后老油田普遍存在注入介质低效循环、注入压力升高、剩余油高度分散等开发难题，现有的提高采收率技术无法高效动用聚合物驱后油藏中的剩余油。文章系统调研并分析了现有的聚合物驱后油藏提高采收率技术及其局限性，明确了聚合物驱后老油田进一步提高采收率亟需突破的关键技术问题，提出利用非氧化型安全环保解堵剂有效解除储层中聚合物的堵塞、采用“堵而不死”深部调剖技术控制深部液流转向、后续注入具有自动找油并高效洗油的新型纳米流体的技术方向，可实现聚合物驱后进一步大幅度提高采收率。

关键词: 聚合物驱后提高采收率, 安全解堵, “堵而不死”深部调剖, 纳米驱油