针对页岩储层无机孔隙和有机孔隙共存的问题,运用双重连续介质方法,结合油相和水相在页岩无机孔隙和有机孔隙中的润湿性和渗流特征,得到油相和水相在页岩中的渗流数学模型。基于该模型拟合页岩油水自吸实验结果,分别得到了页岩的无机孔渗透率和有机孔渗透率,实现了对页岩储层含油量的准确计算,研究了页岩渗流过程的动态特征和影响规律。结果表明:无机孔渗透率为10-8~10-5 D,有机孔渗透率为10-10~10-7 D;随无机孔渗透率、有机孔渗透率的增加,页岩自吸速率加快;当有机孔渗透率与无机孔渗透率比值小于10-3时,有机孔渗透率对自吸速率的影响不显著。研究成果对页岩储层渗透率和储量的精细评价具有重要指导意义。
In order to address the coexistence of inorganic and organic pores in shale reservoirs, a dual-continuum approach was developed to establish a percolation mathematical model for the flow of oil and water phases in shale. This model takes into consideration the wetting and flow characteristics of oil and water phases within both inorganic and organic pores in shale. By employing the proposed model, we obtained matching results from oil-water spontaneous imbibition experiments conducted on shale and determined both the inorganic and organic pore permeability, facilitating accurate calculation of oil content within shale reservoirs. Furthermore, a comprehensive study was carried out to investigate the dynamic characteristics and influential laws of the permeation process in shale. The study results indicate that the permeability of inorganic pores ranges from 10-8 to 10-5 D, while that of organic pores ranges from 10-10 to 10-7 D. As the permeability through inorganic pores increases, the rate of spontaneous imbibition in shale also increases. However, when the ratio of organic pore permeability to inorganic pore permeability is less than 10-3, the impact of organic pore permeability on self-imbibition rate is insignificant. These findings have significant implications for a thorough assessment of permeability and reserves in shale reservoirs.
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