大庆油田萨北区块中渗透砂岩油藏凝胶调剖剂运移吸附试验研究

Experimental Study on the Migration and Adsorption of Gel Profile Control Agent in Medium-Permeability Sandstone in the Sabei Block of Daqing Oilfield

  • 摘要: 大庆油田萨北区块中渗透砂岩油藏经过长期三元复合驱,出现了三元复合体系窜流,导致采收率下降,需要通过凝胶型调剖剂来改善三元复合驱的驱替效果。为了确定三元复合驱条件下凝胶型调剖剂对开发效果的影响,明确其对最终采收率的贡献,开展了凝胶型调剖剂在地层运移中的动态吸附滞留特性研究。利用长度为250 cm的填砂管模型(7个取样点),测试了未成胶聚合物凝胶调剖剂注入过程中各取样点采出液的聚合物质量浓度、体系黏度,以及驱替液与石英砂的微观形貌,研究了调剖剂在运移过程中在岩石上的吸附量和吸附速率、剪切黏度的变化规律及其在驱替液和石英砂表面吸附的微观形貌变化规律。研究结果表明,调剖剂注入过程中,聚合物累计吸附量随注入量增加呈指数增加,而吸附速率随注入量增加呈线性递减。此外,调剖剂黏度动态下降是由黏度剪切和吸附滞留造成的。该研究明确了凝胶型调剖剂在动态运移过程中的吸附滞留变化规律,对于优选体系、合理调配施工工艺及施工方案,以及采油现场调剖作业具有指导意义。

     

    Abstract: After a long period of alkali-surfactant-polymer (ASP) flooding, an ASP system channeling was observed in the medium-permeability sandstone reservoir in the Sabei block of Daqing Oilfield, resulting in a decreased recovery. Therefore, it is necessary to improve the effect of ASP flooding with gel profile control agent. In order to further determine the influence of gel profile control agent on the field development effect under ASP flooding and identify its contribution to ultimate recovery, the dynamics of adsorption and residence of the gel profile control agent during its migration in formation were studied. In this study, the concentration of produced liquid components, the viscosity of the system, and the micromorphology of the displacing fluid and quartz sand were tested at each sampling point during the injection of ungelled polymer gel with a sand-filled pipe model (seven sampling points) with a length of 250 cm. The changes in the adsorption volume, adsorption rate, and shear viscosity of the profile control agent on the rock during the migration and those of the micromorphology on the surface of the displacing fluid and quartz sand during adsorption were studied. The results show that during the injection of profile control agents, the cumulative adsorption volume of polymer increases exponentially with the increase of the injection volume, while the dynamic adsorption rate decreases linearly with the increase of the injection volume. In addition, the decrease of dynamic viscosity of profile control agents is caused by viscosity shear and adsorption and residence. This study clarifies the dynamics of adsorption and residence of gel profile control agent in the process of dynamic migration, which is instructive to optimize the system and reasonable selection of implementation technologies, implementation plan, and profile control on field site.

     

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