聚合物压裂液在页岩油储层的滞留特征研究

doi:10.13809/j.cnki.cn32-1825/te.2025094

摘要/Abstract

摘要： 在页岩油开发过程中,聚合物压裂液是提高油气产量的关键技术之一。然而,聚合物分子量对其压裂效果具有显著影响。聚合物分子量过高可能导致其在储层中的滞留与聚集现象加剧,而分子量过低则可能削弱压裂效果。为了解决这一问题,该研究旨在探索聚合物分子量和质量浓度对页岩油储层中压裂液滞留和聚集行为的影响,以优化压裂液配方,减少对储层的伤害,提高压裂增产效果。通过实验研究和技术分析,选取不同分子量和质量浓度的聚合物溶液,对页岩岩心进行驱替实验。利用微米CT扫描仪和扫描电子显微镜（SEM）技术,对驱替前后的岩心进行观察和对比,分析聚合物在岩心中的滞留和运移特征。实验结果表明：当聚合物分子量低于1 754×10⁴且质量浓度低于2 g/L,滞留效应较弱,表现为孔隙度损失低于8.9%,渗透率下降幅度小于15%,滞留指数低于0.35;而分子量超过1 754×10⁴、质量浓度较高时,滞留效应显著增强,滞留指数可达0.70以上,尤其在裂缝入口附近容易堆积,影响油气流动。研究还发现,聚合物在岩心中的滞留行为受分子量和质量浓度的共同影响,其中分子量是主要影响因素。通过确定适宜的聚合物分子量范围,为减少压裂液在储层中的滞留和聚集提供了科学依据,有助于降低对储层的伤害,提高压裂增产效果。研究成果为优化页岩油压裂液配方提供了科学依据,并对相关领域的技术改进具有一定的参考价值。

关键词: 页岩, 聚合物压裂液, 滞留特征, 微米CT, 扫描电镜

Abstract: In the development of shale oil, polymer fracturing fluid is one of the key technologies for increasing oil and gas production. However, the molecular weight of the polymer significantly affects its fracturing effectiveness. Excessively high molecular weight may exacerbate polymer retention and aggregation within the reservoir, while overly low molecular weight may result in insufficient fracturing effects. To address this issue, this study aims to investigate the influence of polymer molecular weight and concentration on the retention and aggregation behavior of fracturing fluid in shale oil reservoirs, with the goal of optimizing fracturing fluid formulations, minimizing reservoir damage, and improving fracturing efficiency. Through experimental research and technical analysis, polymer solutions with different molecular weights and concentrations were selected for displacement experiments on shale cores. Micro-CT scanners and scanning electron microscopy (SEM) were employed to observe and compare the cores before and after displacement, analyzing the retention and migration characteristics of polymers within the cores. The results showed that when the polymer molecular weight was below 1 754×10⁴ and the concentration was below 2 g/L 1 and 3, where the concentration was 1 g/L—the retention effect was relatively weak. This was manifested as a porosity loss of less than 8.9%, a permeability reduction of less than 15%, and a retention index below 0.35. When the molecular weight exceeded 1 754×10⁴ and the concentration was relatively high, the retention effect was significantly enhanced, with a retention index exceeding 0.70, especially prone to accumulation near fracture entrances, affecting oil and gas flow. Additionally, the study found that polymer retention in cores was jointly affected by molecular weight and concentration, with molecular weight being the main factor. By determining an appropriate range of polymer molecular weight, this study provides a scientific basis for reducing retention and aggregation of fracturing fluid in reservoirs, thereby mitigating reservoir damage and enhancing fracturing performance. The findings offer a scientific foundation for optimizing fracturing fluid formulations in shale oil development and serve as a useful reference for technological improvements in related fields.

Key words: Shale, Polymer Fracturing Fluid, Retention Characteristics, Micro-CT, Scanning Electron Microscope

中图分类号:

TE357

任宇航,吴正彬,杨文博, 等. 聚合物压裂液在页岩油储层的滞留特征研究[J]. 油气藏评价与开发, 0, (): 0-.

REN YUHANG,WU ZHENGBIN,YANG WENBO, et al. Research on retention characteristics of polymer fracturing fluid in shale oil reservoirs[J]. Petroleum Reservoir Evaluation and Development, 0, (): 0-.

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