Determination of petrophysical parameters and estimation of volume of the natural gas storage in Sarajeh field, Qom

This study was carried out in order to determine petrophysical parameters of Sarajeh reservoir rock based on the well logs and rock cores. These data was then employed to evaluate the suitability of the depleted reservoir as natural gas storage. Porosity of the rock was determined from various logs available; effective porosity and permeability were calculated using different empirical relations. Horizontal and vertical permeability of core specimens were measured; the horizontal permeability varied between 0.1 and 1 md and the vertical permeability between 0.01 and 0.1 md. The horizontal permeability was compared with the permeability calculated from log data to evaluate empirical equations for determining permeability. Among the empirical relations, equations suggested by Crain and Wyllie-Rose gave better matches with the core data. Volumetric calculations of the reservoir showed that Sarajeh gas field contains around 5.8 billion m3 of natural gas in standard conditions. Further calculations based on the physico-chemical properties of the natural gas showed that around 1.3 billion m3 of natural gas can be stored and reproduced in the depleted reservoir of Sarajeh gas field.