Inorganic control on original carbonate mineralogy and creation of gas reservoir of the Upper Jurassic carbonates in the Kopet-Dagh Basin, NE, Iran

摘要: The Upper Jurassic Mozduran Formation (Oxfordian–Tithonian) is the main petroleum reservoir in Kopet-Dagh Basin, northeast Iran, which consists predominantly of carbonate rocks with subordinate evaporites and siliciclastics deposited platform to deep marine settings a subtropical sea. Detailed field surveys, petrographic investigations, facies wire line log analyses were carried out at eight surface sections four wells Basin. Integration isotopic data suggests primary low-Mg calcite mineralogy Oxfordian Tithonian ooids. On other hand, wells, Kimmeridgian ooids cements are dominantly aragonitic high-Mg (HMC). Marine isopachous, fibrous isopachous bladed fabrics indicate original aragonite HMC mineralogy, respectively. domination could be related increased hypersalinity, evaporite precipitation consequently an increase Mg/Ca ratio, resulted formation preference calcite. Preserved radial concentric cortices shallow-water that nearby siliciclastic source, together accompanied by drilled fields, suggest was probably controlled inorganically following local salinity variations. This study pay zones mainly depositional facies, diagenetic processes such as dolomitization dissolution.