The present application relates to the technical field of shale pore and fracture analysis, and particularly relates to a shale in-situ
macropore and fracture discrimination method based on
nuclear magnetic resonance-mercury injection. The shale sample in an in-situ state is first obtained; then, two-dimensional
nuclear magnetic resonance testing is performed on the shale sample, and two-dimensional
relaxation spectrum is inverted based on a truncated
singular value decomposition method; in the inversion process, the value range of the
singular value cutoff value is determined based on the two-dimensional
data matrix under different
signal-to-
noise ratios, and the optimal cutoff value is determined through
global optimization; then, high-pressure mercury injection testing is performed on the shale sample, and finally, the
macropore and fracture region in the shale sample is determined by comprehensively considering the high-pressure mercury injection testing result and the two-dimensional
relaxation spectrum. The present application determines the value range of the
singular value cutoff value based on the
nuclear magnetic resonance testing result under different
signal-to-
noise ratios, and determines the optimal cutoff value through
global optimization, so as to improve the inversion effect, obtain more reliable two-dimensional
relaxation spectrum, and then comprehensively discriminate the
macropore and fracture by combining the testing results of nuclear magnetic
resonance-mercury injection, thereby improving the discrimination accuracy.