摘要
随着岩心渗透率降低,毛管力作用增强,岩心驱替测试中的端面效应越加显著,增加了准确获取特低渗岩心相对渗透率曲线的难度。本文基于广泛的特低渗岩心相渗实验数据及端面效应校正基本理论,提出了校正端面效应的简便方法。研究发现当润湿相和非润湿相以固定比例进行驱替实验时,由端面效应引起的压力降与受端面效应影响的岩心区域长度之间存在线性关系,将两者的比值定义为稳定因子;进一步研究发现,稳态法测油水相对渗透率,润湿相与非润湿相比例相同时,岩心稳定因子不随注入流量变化而变化,由此构建了岩心压降与稳定因子的关系式。根据此关系式,只需两组岩心驱替实验便可处理得到不受端面效应影响的非润湿相相对渗透率的大小。通过3组室内实验对新方法进行了验证,结果表明,修正的相对渗透率值误差小于10^(-5)。本文方法大大降低了实验次数,节约了时间和成本,可以快速、准确地修正稳态法测得的特低渗岩心相对渗透率曲线。
With the decrease of core permeability and the enhancement of capillary force, the capillary end effect(CEE) becomes more significant in core displacement experiments, which increases the difficulty of accurately obtaining the relative permeability curve of ultra-low permeability cores. Based on the extensive experimental data of relative permeability of ultra-low permeability cores and the basic theory of CEE correction, this paper proposes a simple method for CEE correction. It’s found that there is a linear relationship between the pressure drop caused by CEE and the length of the core area affected by CEE when the wetting phase and nonwetting phase are displaced at a fixed ratio. The ratio is defined as the stability factor. Further research shows that when steady state method is used to measure oil-water relative permeability, the stability factor doesn’t change with the change of injection flow if the wetting phase and nonwetting phase are at the same ratio. Based on this, the relationship between core pressure drop and stability factor is established. According to this relationship, only two core displacement experiments are needed to obtain the relative permeability of the non wetting phase that is not affected by CEE. The new method is verified by 3 core displacement experiments. The results show that the error of corrected relative permeability is less than 10^(-5). This method greatly reduces the number of experiments and saves time and cost, and can quickly and accurately correct the relative permeability curve of ultra-low permeability cores measured by steady state method.
作者
魏峰
宫汝祥
马俊杰
张雪娜
张宇
刘海涛
WEI Feng;GONG Ruxiang;MA Junjie;ZHANG Xuena;ZHANG Yu;LIU Haitao(CN0OC China Limited,Zhanjiang Branch,Zhanjiang,Grcangdong 524057,China;China Oilfield Services Co.Ltd,Tianjin 300459,China;The Third Oil Production Plant of PetroChina Changqing Oilfield Company,Yinchuan,Ningxia 750006,China)
出处
《中国海上油气》
CAS
CSCD
北大核心
2022年第6期117-123,共7页
China Offshore Oil and Gas
关键词
特低渗岩心
端面效应
稳定因子
相对渗透率
ultra-low permeability core
capillary end effect
stability factor
relative permeability
