A novel method to correct the effect of the internal gradients on the NMR T2 spectrum

The laboratory nuclear magnetic resonance (NMR) measurement and NMR logging have been widely used in formation evaluation since the recorded signal is directly related with the hydrogen. However, the internal magnetic field gradient (G) that is generated from the magnetic susceptibility difference between pore fluid and solid grains, is an important factor that cannot be ignored. It affects the accuracy of NMR logging interpretation and results of fluid identification by accelerating the transverse relaxation of pore fluid through diffusion relaxation, especially in paramagnetic minerals reservoirs such as volcanic and shale.