A Three-Part Study of NMR Longitudinal Relaxation Properties of Water-Saturated Sandstones

Abstract

Summary Borehole measurements of the nuclear magnetic resonance (NMR) properties of rocks have been of interest for many years, especially for estimating permeability. This paper presents laboratory measurements of the NMR properties of water-saturated rocks and shows that permeability can be estimated well with expressions of the form ϕ4T12, where T1 is the relaxation time constant of the longitudinal nuclear magnetization of hydrogen nuclei. Different methods of representing the laboratory-measured T1 curves are shown, including a new one called the stretched-exponential representation. An improved method for estimating T1 parameters from borehole measurements that can be used with either old or new representations is presented.