基于核磁共振的水平井开发孔隙动用机理研究

Study on the Mechanism of Horizontal Well Development Based on NMR

利用三维物理模拟大模型驱替实验,基于核磁共振成像技术及T2谱测量技术,建立了一套研究高含水后期水平井挖潜动用规律的实验技术。应用本技术对Ng5–6油层水平井开采后剩余油分布规律及不同孔喉尺寸孔隙动用规律进行了深入研究。结果表明:高含水期,小孔隙开发程度对于驱替程度较为敏感,而大、中孔隙随驱替程度变化较小。开发过程中,大–中孔隙的原油优先动用,当油藏开发至一定程度后,小孔隙中的原油开始动用;水驱开发后期,小孔隙的动用程度甚至大于大–中孔隙的动用程度,这是由于小孔隙的渗吸作用产生的。应用水平井可以有效开发小孔隙,对主流线区和水平井附近区域的剩余油控制尤其突出,水平井附近区域对采出程度的贡献最大,高含水期采出程度高。

Based on the three-dimension physical model experiment to simulate water flooding and the nuclear magnetic resonance imaging（MRI） as well as the T2 spectrum measuring teehniquein this paper, we establish a series of laboratory experiment methods to study the pore scale producing mechanism of horizontal well development in the high water cut stage. With the experiment methods, the residual oil distribution and different pore scale producing mechanism of horizontal well development for NgS-6 strata is fin＇ther studied. The results show that the relative oil saturation in small pores varies with the degree of displacement, but the relative oil saturation in middle-large pores is almost the same. During the whole displacement progress, middle-large pores act most actively. Until the relative oil saturation of reservoir reduces to an extent, the oil in small pores begins to be produced. The producing extent of small pores is even larger than the middle and large pores when the relative oil saturation of reservoir reduces to an extent because ofimbibition effect. The horizontal well is an effective way to develop small pore. The effect on developing residual oil is especially significant to the main flow area. The central area is critical to the recovery.