In consideration of the high heterogeneity of carbonate reservoirs in the Wumishan Formation

the division criterion between reservoir and non-reservoir is taken

to some extent

as an important factor in evaluation of valuable thickness of a reservoir.Statistical data between residual oil Saturation and porosity in rock samples show that

they are generally in normal correlation and may probably reflect the oil abundance of the underground reservoir rocks

and just so

in 90% of non-petroliferous cores

the porosity is less than 2%

permeability less than 1mD.As the porosity and average size of pores are negatively correlated

it is revealed by capillary pressure curve that the porosity of the unpermeable samples is less than 2%(73%)

and the average size of pores is more than 12.3φ(76%)

the related throat diameter less than 0.21μm.According to electrical log

rocks with GR greater than 3μR/h

the porosity is only 1%

and the permeability is less than 1mD.Based on the measurement of downhole outflow and oil production test

wells with oil output less than 1t per day should be considered to non-reservoirs.The statistic results show that non-reservoirs'GR≥3μR/h

and NG>5.1con.u.So the authors suggest that porosity is 2%

permeability is 1mD and GR>3μR/h

NG>5.1 condition unit should be taken as the dividing criterion between reservoir and non-reservoir.