摘要：

针对钻完井液引起的聚合物堵塞与储层损害问题，本文开发了一种基于纳米载体的改性生物酶解堵剂。通过将α-淀粉酶交联固定在氨基化纳米二氧化硅表面，构建出粒径均匀(约183 nm)、结构稳定的新型固定化酶体系，显著提升了酶的催化活性与环境适应性。系统优化了酶载比、交联剂浓度等关键制备参数，并采用多种手段对比分析了纯酶制剂与固定化酶的分子结构与结合机制。机理研究表明，淀粉酶与氨基化纳米二氧化硅表面的伯胺基团发生脱水缩合反应，生成Schiff碱结构，实现了淀粉酶在纳米颗粒表面的共价固定。在室内模拟实验中，该解堵剂对API泥饼与人工砂盘内部聚合物堵塞展现出快速、高效的清除能力，滤液返排量提高至约120 mL，平均解堵率超过90 %。在95 ℃、3.5 MPa条件下，岩心渗透率恢复率达75.62 %，明显优于传统纯酶体系，体现出更强的高温稳定性与储层保护能力。新型生物酶解堵剂的解堵机制主要通过酶促作用水解聚合物中的α-1, 4或α-1, 6糖苷键，将长链分子切割为短链寡糖或单糖，促使其粘度明显降低，最终实现近井底带的高效解堵和井筒流体返排。此外，新型生物酶解堵剂可以从聚合物降解产物中进行简单离心回收，因此具备多次循环利用的潜力。本研究为生物酶制剂在油田复杂环境中的适应性改性与稳定高效应用提供了新的技术路径和工程思路。

关键词: 生物酶, 钻完井液, 泥饼清除, 解堵, 储层保护

Abstract:

To address the challenges of polymer-induced plugging and reservoir damage caused by drilling and completion fluids, a novel nanocarrier-based immobilized enzyme plug-removal agent was developed in this study. α-Amylase was covalently immobilized on aminated nano-silica particles, resulting in a structurally stable biocatalyst with uniform particle size (~183 nm) and enhanced catalytic efficiency. Key preparation parameters, including enzyme-to-carrier ratio and crosslinker concentration, were systematically optimized. Comparative characterizations were conducted to analyze the molecular structure and binding mechanisms of the native and immobilized enzyme systems. Mechanistic studies have revealed that amylase undergoes a dehydration condensation reaction with the primary amine groups on the surface of aminated nano-silica, resulting in the formation of a Schiff base structure and achieving the covalent immobilization of amylase on the surface of the nanoparticles. Laboratory simulation experiments demonstrated that the developed plug-removal agent exhibited rapid and efficient removal of polymer blockage within API filter cakes and artificial sandpack, increasing the filtrate backflow volume to approximately 120 mL, with an average removal efficiency exceeding 90%. Under high-temperature (95 °C) and 3.5 MPa conditions, the permeability recovery reached 75.62%, significantly outperforming the pure enzyme formulation. The plug-removal mechanism of the novel biological enzyme-based plug-removal agent mainly involves the enzymatic hydrolysis of α-1,4 or α-1,6 glycosidic bonds within polymers. This process cleaves long-chain molecules into short-chain oligosaccharides or monosaccharides, leading to a significant reduction in viscosity and ultimately achieving efficient plug removal in the near-wellbore zone and flowback of wellbore fluids. Additionally, the novel biological enzyme-based plug-removal agent can be easily recovered through simple centrifugation from polymer degradation products, thereby demonstrating potential for multiple recycling and reuse. This work provides a novel strategy and technical solution for enhancing the adaptability and stability of enzyme-based agents for oilfield applications in complex reservoir environments.

Key words: enzyme, drilling and completion fluid, cleaning mud cakes, plugging removal, reservoir protection

中图分类号: 

• TE254.4

• TE39