波谱学杂志2000，Vol.17Issue(3)：177-182,6.
一种改进的核磁共振测井测量脉冲序列
AN IMPROVED MEASURING PULSE SEQUENCE FOR NMR LOGGING
摘要
Abstract
A new pulse sequence for the measurement of NMR logging is proposed in this article, based on the improvement of original CPMG pulse sequence. In the original pulse sequence, after a CPMG pulse sequence, wait time (or T1 relay) is needed to allow the magnetization vector return to equilibrium, then the next measuring CPMG pulse sequence can be applied. The wait time is kept long and the logging speed is low in formations that contain long T1 components, since the logging apparatus is moving continuously along the bore hole. This is unfavorable because the spin-lattice relaxation time (T1) of oil and gas is always long . However, it's noticed that if a 90° pulse from the -x direction (or a 270° pulse from the x direction) is applied after the former CMPG pulse sequence, the long T1 components can be polarized more completely, then the wait time can be shortened and logging speed can be improved. The advantage of the improved pulse sequence is proved by calculations and analyses.关键词
核磁共振/脉冲序列/测井速度/等待时间Key words
NMR/Pulse sequence/Logging speed/Wait time分类
数理科学引用本文复制引用
车文华,张一鸣,夏平畴..一种改进的核磁共振测井测量脉冲序列[J].波谱学杂志,2000,17(3):177-182,6.基金项目
Project supported by National Natural Science Foundation of China(No.59977023) （No.59977023）
