The invention relates to a calibration method for representing dense sandstone pore size distribution by adopting
nuclear magnetic resonance; the method comprises the steps of measuring the rock
porosity and the skeleton density; carrying out a low-temperature broken sample N2 absorption and
desorption experiment, and carrying out a
nuclear magnetic resonance test and a
high pressure Hg
injection test on a regular column sample in a saturated
formation water state; converting pore volume obtained through N2 absorption into
porosity components under different pore
throat radiuses by using a capillary accumulated Hg inlet curve, and establishing a pore proportion summation curve by synthesizing low temperature N2-
high pressure Hg injection; determining a best
calibration coefficient by comparing the
nuclear magnetic resonance pore proportion summation curves under the different C values to realize the conversion between nuclear magnetic
resonance T2 spectrum and the pore
throat radius; establishing a relation between parameters of the
calibration coefficient C and a reflection pore-
throat structure according to lithological characters; carrying out nuclear magnetic
resonance conversion on dense sandstone reservoirs which are positioned in the same region and have the same lithological character. According to the method, the nuclear magnetic
resonance T2 spectrum is calibrated by combining low temperature N2 absorption and a
high pressure Hg injection experiment, and large pores, micropores and mesopores are calibrated, so that the distribution of different grades of pore sizes in dense sandstone can be effectively represented.