在无梯度磁场（non—gradient magnetic field）中测量的饱含甲烷巴尼特页岩岩心塞样品的NMR信号与在甲烷作为一种体积流体（bulk fluid）而弛豫的情况下所测得结果相差很大。在室温条件下，甲烷T2弛豫谱具有10ms级别的模式（mode）。...在无梯度磁场（non—gradient magnetic field）中测量的饱含甲烷巴尼特页岩岩心塞样品的NMR信号与在甲烷作为一种体积流体（bulk fluid）而弛豫的情况下所测得结果相差很大。在室温条件下，甲烷T2弛豫谱具有10ms级别的模式（mode）。这种结果和很大一部分甲烷赋存在纳米级的疏水有机质孔隙中并通过与有机质中氢分子的偶极一偶极相互作用而弛豫是一致的。对于纳米级的孔隙而言，梯度场扩散诱发的任何弛豫都会受到强烈的抑制，因此内部梯度的作用可能是次要的。这些孔隙中的甲烷不会因水基泥浆的侵入而被驱替，所以NMR测量应当能够记录这些孔隙中总的含气量。 巴尼特页岩岩心塞中的NMR水信号具有10ms级别模式（mode）的T：弛豫谱。这种观测结果说明，水要么被粘土束缚，要么赋存在至少部分水湿的非常小孔隙中。 本次研究表明，NMR测井能够定量测定游离气量和有机质孔隙中游离气所占的比例。然而，这需要有全新的测井解释方法，如果采用基于常规储层气体信号的传统测井解释方法，所得结果将是错误的。展开更多
Superconductivity on the border of the long-range magnetic order has been discovered in Mn P under high pressures. In order to investigate the nature of the magnetic properties adjacent to the superconducting state, w...Superconductivity on the border of the long-range magnetic order has been discovered in Mn P under high pressures. In order to investigate the nature of the magnetic properties adjacent to the superconducting state, we performed zero-field 31 P NMR for Mn P single crystal under ambient and hydrostatic pressure of 2 GPa, respectively. Radio frequency power level was used to determine whether NMR signal originates from a helical state or not. When 2 GPa pressure was applied, the signal from helical state exists even above 160 K, while that from the ferromagnetic phase was not observed. Our NMR results indicate that the magnetic phase which is adjacent to the superconducting state is in a helical magnetic structure.展开更多
基金supported by the National Basic Research Program of China(Grant No.2015CB921300)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB07020200)
文摘Superconductivity on the border of the long-range magnetic order has been discovered in Mn P under high pressures. In order to investigate the nature of the magnetic properties adjacent to the superconducting state, we performed zero-field 31 P NMR for Mn P single crystal under ambient and hydrostatic pressure of 2 GPa, respectively. Radio frequency power level was used to determine whether NMR signal originates from a helical state or not. When 2 GPa pressure was applied, the signal from helical state exists even above 160 K, while that from the ferromagnetic phase was not observed. Our NMR results indicate that the magnetic phase which is adjacent to the superconducting state is in a helical magnetic structure.
