RF脈沖及相關(guān)的自旋回波就是所謂的Carr-Purcell-Meiboom (CPMG)序列, 這是應(yīng)用最廣泛的NMR測(cè)井序列。自旋回波信號(hào)的包絡(luò)線隨特征時(shí)問(wèn)常數(shù)(7"2)以指數(shù)規(guī)律衰減, 稱(chēng)為橫向弛豫時(shí)間或自旋一自旋弛豫(衰減)時(shí)間。外推到零時(shí)間(緊跟9O。脈沖)的自旋回波衰減曲線的幅度就等于推導(dǎo)的NMR總孔隙度(假設(shè)流體含氫指數(shù)等于1)。
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