Abstract: The reservoirs in most continental basins in China are of relatively intensive heterogene-ity,common(y of low porosity and low permeability. It is very difficult and complicated to determine the cut-off value of effective throat radia for such reservoirs by conventional meth-ods. Based on our study of the reservoirs of J,S formation in Tu-Ha basin,we propose here a new simple and easy method，by which the cut-off value of effective throat radia for reser-voirs with characters mentioned above is accurately determined from the pore-throat volume versus permeability-contribution curve,and present the theoretical basis,the calculation pro-cedure and the accuracy check of the method. The result obtained by this method is satisfac-tory in quantitative evaluation of reservoirs.

Key words: Pore-throat volume Pore-throat system Permeabili