岩心孔隙介质中流体的核磁共振弛豫

NMR Relaxation of the Fluid in Rock Porous Media

弛豫时间是核磁共振研究中的一个重要参数,岩心孔隙介质流体的弛豫过程是自由流体弛豫机制、表面弛豫机制和流体的扩散弛豫机制共同作用的结果,它包含了丰富的孔隙和流体本身的信息.弛豫时间和自扩散系数的测量及对弛豫时间的分析是核磁共振技术应用于岩心分析和石油勘测的重要内容.

Spin relaxation time measurement is one of the most important applications of NMR technology. Relaxation parameters derived from NMR measurements provide structural and dynamic information of molecules. Applications in porous media further show that the distribution of relaxation time can be use to determine pore size, irreducible water saturation, and formation permeability etc. In this paper we described three relaxation mechanisms and how they can be used to obtain information about rock porous media. Bulk relaxation time of free-fluid is used to differentiate the type of fluids and the quality of oil, surface relaxation distribution provides information of pore size and capillary bonding, and diffusion coefficient improves the capability of fluid typing and pore geometry determination. We also summarized various methods for measuring relaxation times and self-diffusion coefficient, as well as their distributions.