基于核磁共振实验研究致密砂岩渗吸特征

Study on Spontaneous Imbibition Feature of Tight Sandstone Based on NMR Experiment

基于核磁共振实验及岩心压汞测试数据,研究致密砂岩储层自发渗吸过程,定量表征不同级别孔喉对自发渗吸作用的贡献;结合伪彩图像处理技术,对岩心渗吸过程进行可视化观测研究。研究结果表明:致密砂岩自发渗吸不只发生在岩心表面,对深层孔喉也有作用;渗吸过程毛管力起主导作用,重力与浮力作用微弱;识别出测试岩心的渗吸孔喉范围,0.1μm是区分提供渗吸动力喉道和主要泄油喉道的界限;整个渗吸过程可细分为渗吸前期、渗吸中期、渗吸后期3个阶段。

ased on the NMR test and the mercury intrusion porosimetry data,the spontaneous imbibition process of tight sandstone reservoirs was studied,and the contribution of different size of pore throats to the imbibition was quantitatively characterized.The visual observation study on the process of core imbibition was carried out by means of pseudo-color image processing technology.The results show that the spontaneous imbibition of tight sandstone not only occurs on the surface of the core,but also plays an important role in deep pore throats.The capillary force in the imbibition process plays a leading role,and the effect of gravity and buoyancy is weak.The size range of the imbibition pore throat of test cores was determined,and the boundary between the imbibition power throat and the oil discharge throat is 0.1μm;the imbibition process is divided into three stages:the early stage,the middle stage and the late stage.