Petrophysical evaluation of clastic sediments of the Matulla Formation, October oil Field, Gulf of Suez province, Egypt

The present study concerned with evaluation of clastic sediments of Matulla Formation within October field of the Gulf of Suez, Egypt by using wire-line logs and routine core analysis in addition to X-ray diffraction (XRD) analysis. Petrographical results reveal that the studied formation consists of subrounded to subangular, mature, moderately sorted and fine to very fine-grained sandstone. Framework grains are predominantly quartz, feldspar, detrital clay minerals and minor rock fragments. The primary intergranular porosities are dominant in the studied reservoir. Pore-filling authigenic clay coalescing, silica and calcite cementation causes porosity reduction. The diagenes is has critical effects on the reservoir quality, where it can significantly enhance or decrease reservoir qualities depending on affecting process; therefore we can say that the porosity differences are fabric dependant rather than structural dependant. XRD analysis indicates that the Matulla formation constitutes from quartz, plagioclase, K-feldspar, calcite, dolomite, siderite, pyrite and clay minerals with average weight percent reach to 80 %, 2.6 %, 1.5 %, 2 %, 0.5 %, 0.7 %, 0.5 %, and 14 % respectively. The fraction of the clay minerals components assigned 3.5 %, 5 %, 2 % and 3.5 % for Kaolinite, cholorite, illite/mica and mixed layer respectively which reflecting predominant of quartz and clay minerals. The petrophysical results reflect good reservoir properties where the wetted average porosity reaches to 24 %. The vertical and horizontal permeabilities are found up to 186 and 150 md respectively. The permeability anisotropy reflects the dominance of primary depositional fabric rather than secondary depositional fabric. The quantitative analysis of petrophysical wire-line log indicates a considerable amount of hydrocarbon potentiality increasing gradually toward southern part of the studied area with a net pay thickness varies between 35 to 100 ft, low the shale volume (average ≤ 18 %) and good porosity (~ 24 %).