【作者】 姜佳岐； 张元冬； 刘乃贵； 王为民；

【Author】 Jiang Jiaqi;Zhang Yuandong;Liu Naigui;Wang Weimin;Institute of Quantum Electronics,Peking University;INSTITUTE OF GEOLOGY AND GEOPHYSICSCAS;

【机构】 北京大学信息科学技术学院量子电子学研究所； 中国科学院地质与地球物理研究所；

【摘要】 活油衰竭式开采的采收率受注水时机、注水速度、脱气压力等多种因素的影响,.最佳注水时机与注水速度尚无统一认识。在活油衰竭式开采的实验研究中,传统的采收率测量方法将岩心看作一个"黑匣子",存在测量精确度低、获得信息少等缺点。为准确评估注水对活油衰竭式开采的影响,本文选取11块砂岩岩心,开展活油衰竭式开采微观剩余油分布及驱油效率评价的核磁共振实验研究:搭建了一套核磁共振在线测量系统,既可以模拟地层高温高压环境,进行在线驱替,又可以对活油衰竭式开采整个实验过程进行无损、快速、精确测量,获取采收率、原油在不同孔隙中的分布等丰富信息。通过在不同注水时机、注水速度下进行活油衰竭式开采实验,结合开采成本及实现难易程度,得到了活油衰竭式开采最佳的注水时机和注水速度;同时通过分析岩心驱替过程中核磁共振T2谱的变化,为活油衰竭式开采过程中微观驱油机理提供了合理解释。结果表明,活油衰竭式开采过程中被开采出来的油大部分来自T2弛豫时间大于10ms的大孔径,因此,应当先充分利用天然能量进行开采,在天然能量耗尽时再进行注水,这样既能获得较高采收率又最小化了开采成本。降低注水速度虽然可以提高采收率,但提高的幅度非常有限,较高的注水速度依然是活油衰竭式开采的首选。更多还原

【Abstract】 The natural depletion oil recovery is affected by flooding time、flooding speed、pressures and so on.So far there is no consensus on the best flooding time and flooding speed.In the traditional measurement method of oil recovery,we think of rock as a "Black Box".This method works at low precision and gets less information of the rock.To evaluate the effect of flooding on natural depletion accurately,we select 11 sandstone core,and design a NMR experiment of natural depletion Micro-residual oil distribution and evaluation of oil displacement efficiency: We built a NMR online measurement system,which stimulate the stratum temperature and pressure,measure the oil recovery accuratelyd、losslessly and fastly when displacing,and get information of remaining oil distribution.We use T2 spectrum to explain the mirco mechanism of displacement and finally combine the cost to get the optimal flooding time and flooding speed.The results shows that the oil that can be displaced is mostly from the holes whose T2 time is more than 10 ms.We should fully use natural energy,and flood when the natural energy is exhausted.Reduce the flooding speed can improve the recovery rate,but the increase is very limited,the higher flooding speed is still a preferred choice for natural depletion.更多还原