Experimental Investigation on Bio-Enzymatic Plugging Removal Mechanisms and Influencing Factors for Water-Flooding Blockages in Offshore Oilfields

To address severe plugging issues in the near-wellbore zone of offshore oilfields under green development demands, a high-efficiency and eco-friendly bio-enzyme blocking removal and oil displacement technology was proposed. This technology effectively alleviates formation plugging and enhances oil recovery. However, the current lack of in-depth understanding regarding the plugging removal mechanisms of bio-enzymatic compound system for water-flooding blockages has constrained the further advancement and industrial-scale application of this technology. Thus, Based on sand-packed core displacement experiments, a study was conducted on the plugging removal performance of a bio-enzyme compound system under multi-factor perturbations. The influence patterns of different factors on the plugging removal rate of the compound system were elucidated, an evaluation method for the plugging removal effect of the bio-enzyme compound system was established, and injection parameters were optimized. The experimental results show that rhamnolipid surfactant, lipopeptide surfactant, and bio-acid compounding demonstrated significant plugging removal efficacy for water-flooding blockages. The pH and concentration of the bio-enzyme compound system significantly influenced its performance, while reservoir temperature and salinity exhibited relatively minor impacts. Within the experimental scope, a lower pH environment (acidic conditions) and higher enzyme concentration contribute to enhancing plugging removal efficiency; whereas, an increase in formation temperature and water salinity exerts a certain inhibitory effect on bio-enzyme activity, resulting in a slight decline in the system’s plugging removal performance. This study provides theoretical support for optimizing the injection parameters of bio-enzyme compound system in offshore water-flooding blockage removal applications.