Surveying Organic Matter,Thermal Maturity Level,and Paleo-Environmental Conditions by Considering Biomarker and Stable Carbon Isotopic Analysis  

作　　者：Meysam Hemmati Yaser Ahmadi Behzad Vaferi Ali Hosin Alibak David A.Wood 

机构地区：[1]School of Geology,College of Science,University of Tehran,Tehran 14155-6455,Iran [2]Chemical and Petroleum Engineering Department,Ilam University,Ilam 69315/516,Iran [3]Department of Chemical Engineering,Shiraz Branch,Islamic Azad University,Shiraz 7198774731,Iran [4]Petroleum Engineering Department,Faculty of Engineering,Soran University,Soran 44008,Kurdistan Region,Iraq [5]DWA Energy Limited,Lincoln LN59JP,United Kingdom

出　　处：《Journal of Earth Science》2025年第2期428-440,共13页地球科学学刊(英文版)

摘　　要：Biomarker and stable carbon isotope analyses are presented for the Garau Formation of the Cretaceous Age,an important source rock in western Iran,to reveal its potential as an oilprone source rock.The C_(28)/C_(29)sterane ratio value range(0.72 to 0.83)of bitumen samples from the formation suggests that they were likely formed during phytoplankton blooms.Sterane,hopane,and isoprenoid/n-alkane ratios indicate that the formation's organic matter predominantly consists of algae,and bacteria,accompanied by some reworked material derived from higher plants.Due to the predominance of anoxic conditions and the actions of sulfate-reducing bacteria,the bitumen present is enriched with sulfur compounds.The percentages of saturates,aromatics,and nitrogen-sulfuroxygen(NSO)fractions in the bitumen samples classify them as naphthenic oils.Isotope analysis reveals that biodegradation and water-washing have reduced the concentrations of some volatile saturates and low molecular weight aromatics in the bitumen samples.These actions have resulted in distinctiveδ^(13)C values for the formation's kerogen and bitumen fractions.The formation's organic matter has been subjected to high-temperature thermal regimes and has entered the oil-generation window at the sampled localities,with vitrinite reflectance(%R_(C))varying between 0.7%and 0.75%.

关 键 词：source-rock geochemistry biomarkers stable carbon isotopes alteration processes naphthenic crude oil petroleum geology 

分 类 号：P618.13[天文地球—矿床学]