核磁共振技术在致密岩心孔隙量化表征中的应用  

Application of NMR technology in quantitative characterization of tight core pores

作　　者：马超[1,2,3] 黄晓依 高胜天 刘鑫 王诚 MA Chao;HUANG Xiaoyi;GAO Shengtian;LIU Xin;WANG Cheng(School of Petroleum Engineering,Yangtze University,Wuhan 430100,China;Hubei Key Laboratory of Oil and Gas Drilling and Production Engineering(Yangtze University),Wuhan 430100,China;National Engineering Research Center for Oil&Gas Drilling and Completion Technology,Wuhan 430100,China)

机构地区：[1]长江大学石油工程学院,武汉430100 [2]油气钻采工程湖北省重点实验室(长江大学),武汉430100 [3]油气钻完井技术国家工程研究中心,武汉430100

出　　处：《中国科技论文》2024年第5期540-546,574,共8页China Sciencepaper

摘　　要：为了实现致密岩心的孔隙量化表征,采用核磁共振(nuclear magnetic resonance,NMR)技术,利用T2弛豫时间和孔隙半径(r)的正比关系可测致密岩心的孔隙度、渗透率和孔径分布,利用核磁共振T2截止值可区分孔隙中的自由流体和束缚流体。从核磁共振表征岩心孔隙的原理出发,分析了核磁共振T2谱与岩心孔隙度、渗透率、孔径分布、孔隙内可动流体的关系。根据上述原理,通过实例验证了核磁共振技术在致密岩心孔隙度和渗透率量化表征中的准确性和适用性。实验岩心的T2截止值和孔径分布测试表明:1号岩心T2截止值为21.85 ms,2号岩心的T2截止值为40.11 ms;1号岩心小孔隙分量大,2号岩心孔隙分布较均匀。截止值的计算结果表明地区经验法得出的T2截止值不完全适用于该区域的致密岩心,有必要建立区域性的截止值变化范围图版。In order to quantitatively characterize the porosity of tight cores,the porosity,permeability and pore size distribution of tight cores can be measured by nuclear magnetic resonance(NMR)using the proportional relationship between T2 relaxation time and pore radius,and the free fluid and bound fluid in pores can be distinguished by T2 cut-off value.Based on the principle of core porosity characterization by NMR,the relationship between T2 and core porosity,permeability,pore size distribution and movable fluid in pore is discussed.Through above principles and examples,the accuracy and applicability of the NMR in the quantitative characterization of porosity and permeability of tight cores are verified.The cut-off values and pore size distribution tests of the experimental cores show that the cut-off value of core 1 is 21.85 ms and that of core 2 is 40.11 ms.Core 1 has a large small pore fraction and core 2 has a more uniform pore distribution.The results show that the cut-off values of T2 obtained by regional method are not fully suitable to the case of tight core,and it is necessary to establish a regional version of the cut-off variation range chart.

关 键 词：核磁共振 T2谱 孔径分布 致密岩心 

分 类 号：TE327[石油与天然气工程—油气田开发工程]