Matulla Formation in the studied area can be subdivided into lower, middle and upper members. Three main sandstone facies can be identified within the lower and middle members, shore face, tidal channel and beach to tidal flat sand. Each identified facies was studied on the base of shale type, clay minerals and porosity permeability relationship. The shore face of lower member is characterized by dispersed shale in the lower parts and laminated shale in the upper most parts and the illite clay mineral is the most dominant. The porosity ranged from 10 to 16% and the permeability ranged from 1 to 12 mD in the western parts of Muzhil field. In the southern parts, the porosity ranged from 13 to 21% and the permeability ranged from 30 to 130 mD. The tidal channel facies are characterized by dispersed distribution of shale. Glauconite, feldspar, mica and illite are the main clay minerals. This facies exhibit the porosity ranged from 10 to 20% and the permeability ranged from 70 to 100 mD. The beach to tidal flat sand facies are characterized by dispersed to laminated shale. The micaceous matters are abundant with the presence of illite and glauconite clay minerals and the porosity ranged from 14 to 22% and the permeability ranged from 40 to 110 mD in the western part of Muzhil field while in the southern parts, the porosity ranged from 10 to 16% and the permeability ranged from 30 to 130 mD. The shore sandstone facies of middle member are characterized by dispersed shale and illite, glauconite and mica represent the main clay minerals. The shore face of middle member exhibits porosity ranged from 10 to 20% and the permeability ranged from 40 to 120 mD in the southern part of Muzhil field while in the western parts of Muzhil filed, the porosity ranged from 10 to 15% and the permeability ranged from 1 to 12 mD.