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 short-ened and logging speed c an be improved. The advantage of the improved pulse sequence is proved by calcul ations and analyses.

Key words: NMR, Pulse sequence, Logging speed, Wait time