鄂尔多斯盆地长7致密油储层岩心渗吸试验

摘要

The spontaneous imbibition in porous media,as one of frontier subjects in percolation studies of fractured reser-voirs,has been investigated in the development of tight oil reservoirs via water-flood huff and puff process. It has indicated that,based on the current research, water imbibition mainly depends on the relative contribution of capillary and gravity forces,which are dominated by different regimes in different fluid systems. In this study,based on the NMR analysis meth-od,the imbibition experiments of Chang7 tight oil cores were carried out,and the experimental data were analyzed with fully understanding the pore-throat structures and accurate oil/water saturation from the NMR analysis. The experimental results show that the final oil recovery is closely related to the inverse Bond number in static imbibition experiments. The ultimate oil recovery of Chang7 tight oil cores is 30%-35%,and the critical inverse Bond number required to achieve the maximum oil recovery is about 1. In comparison of the static imbibition and dynamic displacement experiments,the results show that the smaller of the dynamic displacement rate,the lower of the oil recovery in the large pore-throat regions,while the distribution of oil and water saturation is basically the same in small pore-throat regions. The experimental study on the water imbibition of Chang7 tight oil cores in Erdos Basin can provide useful guidelines for improved oil recovery via applying the water-flood huff and puff technique in tight and fractured oil reservoirs.%根据对水渗吸理论和渗吸试验的研究,渗吸作用力主要为重力和毛管力,两种作用力在不同渗吸条件和渗流阶段占不同的主导地位.采用核磁共振技术,结合长7致密油岩心渗吸试验,在核磁分析岩心内部孔喉结构和精确度量油水饱和度变化的前提下对渗吸结果进行分析.结果表明:静态渗吸采收率与Bond数的倒数密切相关,鄂尔多斯盆地长7致密岩心渗吸采收率为30% ~35%,最佳渗吸采收率时的Bond数倒数值约为1.对比动态渗吸驱替与静态渗吸试验结果发现,驱替速率越小,大孔喉内原油采收率越低,而小孔喉内的油水饱和度基本相同.鄂尔多斯盆地致密油长7储层渗吸规律的研究,为致密油注水吞吐开发、提高裂缝性水湿油藏的采收率提供理论基础.