Resumen de Facies analysis and petrophysical properties of the lithologies of the north gas field, Qatar
Hanafy M. Holail, Mossbah M. Kolkas, Gerald M. Friedman
Petrographic analysis of selected core samples from Khuff (Permian-Early Triassic) and Hanifa (Lower Jurassic) Formations of Qatar indicates that their lithologies were deposited within a tidally influenced shallow-marine environment. The lithofacies of the Khuff and Hanifa Formations mainly consist of a basal sandstone unit overlain by carbonate grainstone, oolitic dolostone, bioclastic mudstone, and dolomicrite with anhydrite laths.
A sequence of diagenetic modifications were recorded as follows: 1) deposition of the original sediments; 2) early dolomitization; 2) late dolomitization; 3) chemical compaction (stylolitization), and 4) precipitation of pore-filling calcite and dolomite.
Geochemical analysis of the selected samples reveals that the lithologies of the Hanifa Formation contain high organic matter, high genetic potential, and mature kerogen. These factors made the Hanifa Formation an excellent source for the liquid hydrocarbons. Khuff Formation is considered to be an excellent source for gaseous hydrocarbons because it depicts a low concentration of organic carbon, very low genetic potential, and very high mature organic matter.
Quantitative-petrophysical analyses of selected core plugs, using a mercury-porosimetric technique, indicate that the petrophysical parameters including porosity, permeability, recovery efficiency, pore diameter, and fluid saturation vary among the rock formations. These variations are controlled by diagenetic modification.
