Reservoir character of pelitic dolostone in the Xiagou Formation, Lower Cretaceous, Qingxi Oilfield, NW China

Pelitic dolostone, including argillaceous dolostone, dolomitic mudstone, and dolostone, in the Xiagou Formation, Lower Cretaceous, Qingxi Oilfield, is of reservoir with lowest permeability and porosity, which has been buried beneath 3600m with abundant felsic micrograin, its matrix porosity is less than 5% and matrix permeability less than 0. 5mD. The analyses of sedimentary facies zone, rock components, pore types and matching features have been used for forecasting the distribution of favorable reservoirs and a better exploration effect is attained