Mobile NMR for porosity analysis of drill core sections

Abstract

We apply a novel mobile nuclear magnetic resonance (NMR) scanning system, the NMR-MOUSE® (NMR-MOUSE (Nuclear Magnetic Resonance Mobile Universal Surface Explorer) is a registered trademark of RWTH Aachen University), for measuring porosity of geological drill core sections. The NMR-MOUSE® is used for transverse relaxation measurements on water-saturated core sections using a CPMG sequence with a short echo time. A regularized Laplace-transform analysis by the UPEN program yields the distribution of transverse relaxation times. The signal amplitudes and the distribution integrals correlate directly with the porosity of the cores, in spite of the influence of diffusion in the strong field gradient of the NMR-MOUSE®, which is discussed. The method is particularly attractive because it neither requires a volume calibration nor the samples to be machined to fit the coil, and because the device is mobile and particularly attractive for field use such as on logging platforms and research vessels. © 2004 Nanjing Institute of Geophysical Prospecting.