Biomarker Indicators of Source and Depositional Environment for the Organic Matters within Barsarin Formation (Upper Jurassic) in Kirkuk and Taq Taq Oil Fields, Northern Iraq

Abstract

The GC, GC/MS analysis for twelve bitumen extracts from Barsarin Formation in the wells K-109 and Tq-1 (Kirkuk and Taq Taq oil fields respectively) and for two oil samples from K-156 and Tq-1 wells revealed a euxinic, carbonate marine to mix environment for the initial organic matters. Pr / Ph, Pr / nC17, and Ph / nC18 ratios indicated also a marine source organic matters deposited under reduced condition with a less effect of biodegradation and mature stage of occurrence. The diasteranes / steranes ratio showed generally low ratios (0.27 – 0.56) as in most marine carbonate sources, while Algal-bacterial organic matter contribution for the extracts and the oil samples suggested depending on the predominance of C23 tricyclic terpane relative over the C19 tricyclic terpane and the C23 tricyclic terpane greater than C24 tricyclic terpane. The gammacerane Index indicated a low salinity environment of deposition for the initial organic matters existed in the analyzed samples.

Keywords

• biomarker
• indicators
• source
• depositional
• environment
• organic
• matters
• within
• barsarin
• formation
• upper jurassic
• kirkuk and taq taq oil fields
• northern iraq