The Carboniferous gas reservoir in X gasfield consists of four well blocks: well block X17, X14, X18 and X10. On the basis of lithology research, seven different reservoir matrix parametric charts are established. According to reservoir lithology and differences of the lithofacies characteristics, four types of litho-electrical parameters charts of basalt, rhyolite, irruptive rock, glutinite are set up. Based on the studies of reservoir parameters, a variety ofmethods are used to determine the lower limits of the effective thickness of different lithological division in order to provide accurate reserve parameters on reservoir description. Through coring wells gas saturation analysis and porosity test results, the calculated porosity and gas saturation results meet the error requirements of reserve calculation, which plays an important role in proved reserves calculation of Carboniferous in X gasfield.