球管孔隙模型的核磁共振(NMR)弛豫特征及应用

将岩石孔隙归结为由毛细管和球形孔组成的孔隙系统，提出孔隙球管孔隙模型. 岩石孔隙按大小分组后，每一组孔隙的氢核弛豫时间可以用球管孔隙模型计算. 将此弛豫时间作为反演T2分布的时间控制点，反演岩芯的核磁共振弛豫信号. 研究表明， T2分布与特定的孔隙结构相联系. 使用不同结构的球管孔隙模型，可以使反演T2分布最大限度地拟合弛豫信号，此时的球管模型以最近似的方式模拟了岩芯的孔隙结构. 使用球管模型对实验室核磁共振资料进行了处理，对比压汞分析得到毛管力分布数据，结果证明球管孔隙模型描述了岩石孔隙的弛豫特征，而且，岩石特定孔隙结构的弛豫特征与孔隙流体有关.

APPLICATIONS AND CHARACTERIZATION OF NMR RELATION DERIVED FROM SPHERE-CAPILLARY MODEL

All pores in rock can be regarded as a system consisting of spherical pore and capillary pores. This paper presents a model of sphere-capillary. All pores are divided into different groups by their radii, and the relaxation time of each group can be calculated with the sphere-capillary model. The transversal relaxation time (T 2), spaced on the sphere-capillary model, can be utilized to conduct the inversion of NMR relaxation signal. Our research suggests that the T 2 distribution from the inversion is related with the special pore structure defined by the sphere-capillary model. Using different sphere-capillary models to derive different relaxation times, we conduct the inversion of relaxation signal with the relaxation time. When a T 2 distribution fits the relaxation signal in the least squares, the pore structure defined by the sphere-capillary model characterizes the pore system in rock best. Data from lab NMR measurements are analyzed with the sphere-capillary model, and the results are compared with the pressure data from mercury injection. The result shows that the sphere-capillary model describes properly the relaxation characteristic related with pore structure. Furthermore, the relaxation characteristic may be associated the with pore fluids.