NUCLEAR MAGNETIC RESONANCE METHOD AND APPARATUS FOR DETERMINING PORE CHARACTERISTICS OF ROCKS AND OTHER POROUS MATERIALS

摘要

the invention involves a method for determining a pore characteristic of a substance, which includes subjecting the substance to a substantially uniform static magnetic field; applying a magnetic pulse sequence to the substance, the pulse sequence being selected to produce nuclear magnetic resonance signals that are responsive to internal magnetic field inhomogeneities in the pore structure of the substance, and detecting, as measurement signals, nuclear magnetic resonance signals from the substance; applying a reference magnetic pulse sequence to the substance, the reference pulse sequence being selected to produce nuclear magnetic resonance signals that are substantially unresponsive to internal magnetic field inhomogeneities in the pore structure of the substance, and detecting, as reference measurement signals, nuclear magnetic resonance signals from the substance; and determining a pore characteristic of the substance from the measurement signals and the reference measurement signals. A related method and apparatus for determining a pore characteristic of formations surrounding an earth borehole are also disclosed.