INVERSE MODEL OF CAPILLARY PRESSURE CURVE FOR SANDSTONE RESERVOIR ROCKS

The pore throat size distribution of reservoir rock is an important parameter used in reservoir evaluation. The porosity and permeability of reservoir are synthetically macroscopic reflection of microscopic reservoir pore structure characteristics. Through analyses of mercury injection data and poroperm data of 393 sandstone samples collected from Tuha, Liaohe, Shengli and Sichuan oil and gas fields in China, it is found that for sandstone reservoir rocks there exists a close relationship between porosity and permeability (especially permeability) and pore volume distribution by characteristic throat sizes. Based on this realization, inverse models of capillary pressure curve, i.e. the predictive model of reservoir pore throat distribution, are established. These models can solve the problem encountered in the study of reservoir pore structure where that is a shortage of mercury injection data or core samples for some layers or some wells of an area. Also, these models can help correctly evaluate heterogeneity of reservoir pore structure.