Method for correcting porosity of gravelly sandstone reservoir

The invention relates to the field of oil and natural gas prospecting and development and in particular relates to a method for correcting the porosity of a gravelly sandstone reservoir. According to the method, the porosity of the gravelly sandstone reservoir is subjected to coarse clastic particle content correction by taking 7 mm as the upper limit diameter of clastic particles capable of being normally drilled by a standard rock core column sample on the basis of macroscopic detail description of full diameter core of gravelly sandstone and corresponding porosity testing of the standard rock core column sample; the problem that the porosity measured by the standard rock core column sample with the diameter of 25 mm is larger than the actual porosity of the gravelly sandstone reservoir as no pores exist in undrilled coarse clastic particles but the volume of the rock sample is occupied can be solved, so that the porosity prediction precision of the gravelly sandstone reservoir is improved and the risk of oil-gas exploration is lowered.