基于核磁共振技术水驱油剩余油分布评价

Microscopic Experimental Study on Water Displacement Oil Based on Nuclear Magnetic Resonance Technology

为了研究油藏水驱油微观机理及不同井区的水驱油影响因素,将水驱油物理模拟实验和核磁共振技术相结合,对不同井区岩样不同阶段水驱油后剩余油分布情况进行分析,分别对文昌区A、B井及涠洲区C井进行研究。结果表明:水驱油前,小孔隙基本不含油,油主要分布于中等孔隙和大孔隙内;水驱油后,A井和C井驱油效率中等孔隙高于大孔隙,岩样表现为亲水性,中高渗储层非均质性强,使得大孔隙驱油效率低;B井大孔隙驱油效率远高于中小孔隙,注入水主要波及大孔隙,难以波及中小孔隙。油田开发过程中,通过增加驱替速度可以增加采收率。长期水驱可以增加油藏采收率,亦可通过调剖、堵水等措施,进一步提高水驱油开发潜力。因此对于中高渗储层来说,通过对不同孔隙剩余油分布规律的研究,有利于进一步完善注水开发方式,提高油田的动用效果。

In order to study the micro mechanism of reservoir water displacement oil and the influence factors of different well areas, the paper combines water displacement physical simulation experiment and NMR technology to analyze microscopic oil distribution characteristics both in initial state and after water displacing. The Wenchang A, B wells and Weizhou C wells are used as studying examples. The results show that before water flooding, oil mainly was distributed in medium and large pores, almost no oil in small pores; After water flooding, the displacement efficiency of medium pores of A and C wells are much higher than that of large pores. The core is hydrophilic, and the heterogeneity of medium and high permeability reservoirs are strong, which leads to the low efficiency of the oil displacement. The displacement efficiency of large pores of B well is much higher than that of small and medium pores. Large pores are mainly swept by injected water, small and medium pores are difficult. In the process of oil field development, the oil recovery rate can be improved by increasing the driving speed. Long term water flooding has a certain effect on increasing oil recovery, and can improve the effect of water flooding by profile control and water shutoff. Therefore, for the medium and high permeability reservoirs, the study of the distribution of remaining oil in different pores is helpful to improve the water injection development mode and improve the production efficiency.