Application Basis of Nuclear Magnetic Resonance Technology in the Unconventional Reservoirs

The application interpretation of nuclear magnetic resonance (NMR) technology in unconventional reservoirs has been very controversial. A new interpretation method of NMR spectrum is proposed and applied to the unconventional reservoirs combining with the concept of seepage fluid. The results show that the left peak and right peak of nuclear magnetic resonance spectrum in tight oil and gas sandstone cores are continuous rather than entirely separated, which indicates that the properties of the differences between the easy-to-produce fluid and the difficult-to-produce fluid is not completely separated. But the nuclear magnetic resonance spectrum of shale and coal bed methane (CBM) reservoir cores is opposite to the above mentioned results. In cores of unconventional reservoirs, the difficult-to-produce fluid dominates, and the easy-to-produce fluid in tight oil and gas sandstone cores is more than that of shale and CBM reservoir cores. The recovery degree of tight oil and gas sandstone reservoirs mainly increases in the easy-to-produce fluid extraction, but the recovery degree of shale and CBM reservoirs mainly increases in the difficult-to-produce fluid extraction.