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<p>To elucidate the dominant mechanism by which pore-throat structures influence imbibition oil recovery in tight sandstone reservoirs, this study conducted experiments on natural core samples obtained from tight sandstone reservoirs. The pore-throat structures of the cores were characterized using scanning electron microscopy (SEM) and high-pressure mercury intrusion porosimetry (MIP). Based on this, spontaneous imbibition experiments combined with nuclear magnetic resonance (NMR) technology were employed to monitor real-time signal intensity changes of fluorinated oil and water within pores of different sizes. This approach identified the dominant driving forces for imbibition in various pore-throat types and quantitatively characterized the contribution of different pore scales to imbibition oil recovery in tight sandstone reservoirs. The results show that higher permeability corresponds to greater fluid displacement efficiency. In reservoirs with higher permeability, gravity serves as the dominant driving force during imbibition, and macropores (pore diameter &gt; 1&#xa0;μm) contribute the majority of the imbibition oil recovery. In reservoirs with lower permeability, both gravity and capillary forces play significant roles in imbibition. Fluid displacement mainly occurs in the early stage of imbibition, with weaker displacement in the later stage. Macropores contribute most of the imbibition recovery, mesopores (pore diameter 0.1–1&#xa0;μm) contribute a small portion, while micropores (pore diameter 0.025–0.1&#xa0;μm) and nanopores (pore diameter &lt; 0.025&#xa0;μm) also contribute marginally. Whether the dominant force is gravity or capillary force, macropores and mesopores are the primary sources of imbibition oil recovery, indicating that oil content and pore connectivity are crucial factors influencing imbibition efficiency. This study provides useful guidance for enhancing oil recovery through spontaneous imbibition in tight sandstone reservoirs.</p>

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The influence of pore throat structure on fluid displacement in tight oil reservoir

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年5月10日

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  • Xiong Liu,
  • Yirui Ren,
  • Nan Wang,
  • Yueqi Cui,
  • Zhiyuan Du

摘要

To elucidate the dominant mechanism by which pore-throat structures influence imbibition oil recovery in tight sandstone reservoirs, this study conducted experiments on natural core samples obtained from tight sandstone reservoirs. The pore-throat structures of the cores were characterized using scanning electron microscopy (SEM) and high-pressure mercury intrusion porosimetry (MIP). Based on this, spontaneous imbibition experiments combined with nuclear magnetic resonance (NMR) technology were employed to monitor real-time signal intensity changes of fluorinated oil and water within pores of different sizes. This approach identified the dominant driving forces for imbibition in various pore-throat types and quantitatively characterized the contribution of different pore scales to imbibition oil recovery in tight sandstone reservoirs. The results show that higher permeability corresponds to greater fluid displacement efficiency. In reservoirs with higher permeability, gravity serves as the dominant driving force during imbibition, and macropores (pore diameter > 1 μm) contribute the majority of the imbibition oil recovery. In reservoirs with lower permeability, both gravity and capillary forces play significant roles in imbibition. Fluid displacement mainly occurs in the early stage of imbibition, with weaker displacement in the later stage. Macropores contribute most of the imbibition recovery, mesopores (pore diameter 0.1–1 μm) contribute a small portion, while micropores (pore diameter 0.025–0.1 μm) and nanopores (pore diameter < 0.025 μm) also contribute marginally. Whether the dominant force is gravity or capillary force, macropores and mesopores are the primary sources of imbibition oil recovery, indicating that oil content and pore connectivity are crucial factors influencing imbibition efficiency. This study provides useful guidance for enhancing oil recovery through spontaneous imbibition in tight sandstone reservoirs.