Experimental Research on the Microscopic Imbibition Mechanism of Tight Sandstone Oil Reservoirs

doi:10.12388/j.issn.1673-2677.2025.04.006

Abstract

Abstract:

Imbibition，as one of the main methods to improve the degree of crude oil production in tight sandstone reservoirs，has attracted much attention. Measurement errors of produced oil in imbibition tests lead to wrong evaluation of imbibition performance. Taking the Chang 7 Member of the Yanchang Formation of the Luohe Oilfield in the Ordos Basin as the research object，the effects of imbibition time，interfacial tension，wettability，rock physical properties and imbibition pressure on the imbibition efficiency were studied at the microscopic pore scale through experimental methods such as high-pressure mercury injection and nuclear magnetic resonance. The results show that：（1） The pore structure of the Chang 7 Member core is dominated by small pores，and the capillary force is the main driver for imbibition. With 96 hours of imbibition，the imbibition efficiency of cores reaches a plateau，and the imbibition efficiency of small pores controls the imbibition efficiency of the core. （2） Due to the large seepage resistance of small pores，the imbibition efficiency of small pores is affected by both the driving force and resistance of dialysis. With the decrease in core permeability and interfacial tension，the imbibition efficiency shows a fluctuating trend，and with the increase in the wetting angle，it decreases significantly. （3） When the permeability is lower than 1 mD，the imbibition resistance controls the imbibition efficiency. As the permeability increases，the influence of the imbibition driving force is strengthened. The Chang 7 Member core presents the best imbibition efficiency in the case of an interfacial tension of 3.08 mN/m，a wetting angle of 20°，and an imbibition pressure coefficient of 1.45. The findings of this research provide references for improving the interfacial tension，wettability and imbibition pressure of imbibition treatment media.

Key words:

tight sandstone reservoir, imbibition, interfacial tension, wettability, rock permeability, rock porosity

摘要：

渗吸作为致密砂岩油藏提高原油动用程度的主要方法之一而备受关注。渗吸实验中产出原油的测量误差会导致渗吸效果评价出现偏差。以鄂尔多斯盆地洛河油田延长组长7段岩心为研究对象，通过高压压汞、核磁共振等实验方法，从微观孔隙尺度方面研究渗吸时间、界面张力、润湿性、岩石物性和渗吸压力系数对渗吸效率的影响。结果表明：1）长7段岩心孔隙结构以小孔为主，毛管力为渗吸的主要动力，渗吸时间96 h时，岩心渗吸效率达到平衡值，小孔渗吸效率控制岩心的渗吸效率；2）小孔由于渗流阻力大，渗吸效率受渗吸动力和阻力的双重影响，随岩心渗透率和界面张力降低，其渗吸效率呈波动变化趋势，随润湿角增加，小孔渗吸效率明显降低；3）当渗透率低于1 mD时渗吸阻力控制渗吸效率，随渗透率增加渗吸动力的影响加强。长7段岩心在界面张力为3.08 mN/m、润湿角20°和渗吸压力系数1.45的条件下渗吸效率最佳。该研究成果对致密油藏优化渗吸液界面张力、润湿性和渗吸压力具有指导意义。

关键词:

致密砂岩油藏, 渗吸, 界面张力, 润湿性, 岩石渗透率, 岩石孔隙度

CLC Number:

TE311

DENG Xuefeng, WEI Kaipeng.

Experimental Research on the Microscopic Imbibition Mechanism of Tight Sandstone Oil Reservoirs [J]. Xinjiang Oil & Gas, 2025, 21(4): 47-55.

邓学峰, 魏开鹏.

致密砂岩油藏微观渗吸机理实验研究 [J]. 新疆石油天然气, 2025, 21(4): 47-55.

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