Ma Yunfei, Hou Jirui, Zhao Fenglan, Song Zhaojie
Enhanced Oil Recovery Research Institute, China University of Petroleum Beijing China
Beijing Key Laboratory of Greenhouse Gas Sequestration and Oil Exploitation and Application China.
RSC Adv. 2018 Feb 22;8(15):8269-8284. doi: 10.1039/c8ra00362a. eCollection 2018 Feb 19.
Alkaline-surfactant-polymer (ASP) flooding is considered to be one of the most promising tertiary oil recovery techniques. Nevertheless, its low sweep efficiency in a multilayer heterogeneous reservoir limits field applications. In this work, linearly descending viscosity, a novel injection pattern of ASP flooding, was used for mobility control. Three-dimensional multilayer heterogeneous core models were designed and fabricated. ASP flooding experiments were conducted in the laboratory, and the remaining oil distribution was measured during flooding. Fluid samples obtained from production wells were used for the viscosity measurement. Contrast experiments were made using another two injection patterns including constant viscosity fluid injection and linearly ascending viscosity fluid injection. The results indicated that ASP flooding with linearly descending viscosity improved oil recovery by over 25%, which was a better performance than that obtained using the other two injection patterns. As the different injection patterns presented a similar recovery in the high permeability layer, the sweep efficiency of ASP fluid in the middle and low permeability layers contributed to the difference in the ultimate oil recoveries. In addition, the initial viscosity of the ASP slug had the greatest effect on the mobility modification. Linearly descending viscosity had the highest initial viscosity, leading to the highest fluid distribution rate in the middle and low permeability layers. In addition, higher effluent viscosity was obtained and an earlier viscosity peak occurred in ASP flooding with linearly descending viscosity. Therefore, the sweep efficiency in middle and low permeability layers was remarkably enlarged by using linearly descending viscosity. Thus, increasing the viscosity of the displacement agent as early as possible was found to be significantly in a multilayer heterogeneous reservoir. This study provides an insight into ASP flooding in multilayer heterogeneous reservoirs.
碱性表面活性剂聚合物（ASP）驱油被认为是最有前景的三次采油技术之一。然而，其在多层非均质油藏中的低波及效率限制了现场应用。在这项工作中，采用线性降黏这种新型的ASP驱油注入方式来控制流度。设计并制作了三维多层非均质岩心模型。在实验室进行了ASP驱油实验，并在驱油过程中测量了剩余油分布。从生产井获取的流体样本用于黏度测量。使用另外两种注入方式进行对比实验，包括注入恒黏流体和线性升黏流体。结果表明，线性降黏ASP驱油提高采收率超过25%，其性能优于另外两种注入方式。由于不同注入方式在高渗透层的采收率相近，ASP流体在中低渗透层的波及效率导致了最终采收率的差异。此外，ASP段塞的初始黏度对流度调整的影响最大。线性降黏具有最高的初始黏度，使得中低渗透层的流体分配率最高。此外，线性降黏ASP驱油获得了更高的产出液黏度，且黏度峰值出现得更早。因此，采用线性降黏显著提高了中低渗透层的波及效率。由此发现，在多层非均质油藏中尽早提高驱替剂黏度非常重要。本研究为多层非均质油藏中的ASP驱油提供了见解。
