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| A new method of estimating NMR T2 spectrum of sandstone |
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YAN Weichao1, SUN Jianmeng1, CUI Likai1, YAN Guoliang2
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(1.School of Geosciences in China University of Petroleum, Qingdao 266580, China;2.Research Institute of Petroleum Exploration ＆ Development-Northwest, PetroChina, Lanzhou 730020, China)
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| Abstract: |
| Based on nuclear magnetic resonance(NMR)relaxation mechanism and three-dimensional digital core technology, a new method of estimating the spectrum of sandstone transverse relaxation time (T2) is established. A process-based method was used to reconstruct 3D digital rock models of sandstone. Sandstone microstructures were divided into tetrahedral pore units using Delaunay tessellation. Considering the geometry and using a Monte Carlo approach, the surface-to-volume ratio (S/V) of each pore unit was calculated, and then the T2 spectrum of sandstone could be simulated. After a large number of simulations, suitable parameters were selected in order to reduce calculation errors. Unimodal and bimodal T2 spectrum were considered; both results agreed well with laboratory tests. This new method is helpful in studies of different NMR response effects with varying grain sizes or pore structures. |
| Key words: NMR T2 spectrum digital core process-based method Delaunay tessellation Monte Carlo method |
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