The sources and enrichment of organic matter in a sediment core in the first member of the Xiagou Formation(K_1g^1) from the Chang 2-2 borehole of the Jiuquan Basin,NW China,have been examined using Rock-Eval,maceral,...The sources and enrichment of organic matter in a sediment core in the first member of the Xiagou Formation(K_1g^1) from the Chang 2-2 borehole of the Jiuquan Basin,NW China,have been examined using Rock-Eval,maceral,carbon isotopes and biomarker data.This data indicates that highly variable organic matter sources and preservation conditions in response to climate change.TOC content,HI,and δ^(13)C value were strongly correlated with the abundance of gammacerane,woody organic matter content,steranes/hopanes ratio,and C_(29) sterane content.This correlation demonstrates the importance that the control of the salinity of the depositional environment and organic matter sources can have upon the enrichment,type,and carbon isotopic composition of organic matter.In the Jiuquan Basin's relatively high temperature and arid climate,high salinity lakes with high primary productivity of algae,planktons,and bacteria,and good organic matter preservation conditions(anoxic bottom water) resulted in the enrichment of isotopically-light algae-bacterial organic matter.In the Jiuquan Basin's regions with a relatively low temperature and wet climate,fresh lakes with low primary productivity of algae,planktons,and bacteria received significant terrigenous high plants input,resulting in the deposition of a low abundance of isotopically heavier terrestrial organic matter.展开更多
Shales in the Carboniferous–Permian Fengcheng(FC) and Lucaogou(LCG) formations in Junggar Basin are important organic rich rocks containing significant oil resources.To evaluate the difference in sedimentary environm...Shales in the Carboniferous–Permian Fengcheng(FC) and Lucaogou(LCG) formations in Junggar Basin are important organic rich rocks containing significant oil resources.To evaluate the difference in sedimentary environment conditions and hydrocarbon-generating potential between the FC and LCG formations.Total organic carbon(TOC),Rock-Eval pyrolysis,solvent extraction,column fractionation,stable carbon isotope,gas chromatography-mass spectrometry(GC-MS) of saturated hydrocarbons and organic petrology from the source rocks of FC and LCG formations.were analyzed.The biomarker composition indicates that during the deposition of FC,LCG-1 to LCG-2,the sedimentary environment for the source rock formations changed with gradual decrease of salinity,from anoxic to dyoxic/suboxic in redox conditions,and from strong stratification to weakened stratification of water.The FC Formation source rock,with main telalginite(planktonic green algae),archaebacteria and minor terrestrial organic matter,deposited in the environment characterized by high salinity and strongly reducing condition.Its TOC content is relatively low with a high original hydrocarbongenerating potential of unit organic material.The LCG Formation source rock deposited in the environment with low salinity and large variations,the organic matter is mainly sourced from telalginite(planktonic green algae),lamalginite,bacteria and higher plants,resulting in strong heterogeneity of the source rock.The abundance of TOC is high,but the original hydrocarbon generation potential of unit organic matter is lower than that of FC Formation.The results provide a geochemical basis for further study of saline-brackish water sedimentary environment shales in the Junggar Basin.展开更多
基金financially supported by CNPC Major Science and Technology Project (NO. 2012E330)CNPC Fourth Petroleum Resources Assessment (NO. 2013E-050209)
文摘The sources and enrichment of organic matter in a sediment core in the first member of the Xiagou Formation(K_1g^1) from the Chang 2-2 borehole of the Jiuquan Basin,NW China,have been examined using Rock-Eval,maceral,carbon isotopes and biomarker data.This data indicates that highly variable organic matter sources and preservation conditions in response to climate change.TOC content,HI,and δ^(13)C value were strongly correlated with the abundance of gammacerane,woody organic matter content,steranes/hopanes ratio,and C_(29) sterane content.This correlation demonstrates the importance that the control of the salinity of the depositional environment and organic matter sources can have upon the enrichment,type,and carbon isotopic composition of organic matter.In the Jiuquan Basin's relatively high temperature and arid climate,high salinity lakes with high primary productivity of algae,planktons,and bacteria,and good organic matter preservation conditions(anoxic bottom water) resulted in the enrichment of isotopically-light algae-bacterial organic matter.In the Jiuquan Basin's regions with a relatively low temperature and wet climate,fresh lakes with low primary productivity of algae,planktons,and bacteria received significant terrigenous high plants input,resulting in the deposition of a low abundance of isotopically heavier terrestrial organic matter.
文摘Shales in the Carboniferous–Permian Fengcheng(FC) and Lucaogou(LCG) formations in Junggar Basin are important organic rich rocks containing significant oil resources.To evaluate the difference in sedimentary environment conditions and hydrocarbon-generating potential between the FC and LCG formations.Total organic carbon(TOC),Rock-Eval pyrolysis,solvent extraction,column fractionation,stable carbon isotope,gas chromatography-mass spectrometry(GC-MS) of saturated hydrocarbons and organic petrology from the source rocks of FC and LCG formations.were analyzed.The biomarker composition indicates that during the deposition of FC,LCG-1 to LCG-2,the sedimentary environment for the source rock formations changed with gradual decrease of salinity,from anoxic to dyoxic/suboxic in redox conditions,and from strong stratification to weakened stratification of water.The FC Formation source rock,with main telalginite(planktonic green algae),archaebacteria and minor terrestrial organic matter,deposited in the environment characterized by high salinity and strongly reducing condition.Its TOC content is relatively low with a high original hydrocarbongenerating potential of unit organic material.The LCG Formation source rock deposited in the environment with low salinity and large variations,the organic matter is mainly sourced from telalginite(planktonic green algae),lamalginite,bacteria and higher plants,resulting in strong heterogeneity of the source rock.The abundance of TOC is high,but the original hydrocarbon generation potential of unit organic matter is lower than that of FC Formation.The results provide a geochemical basis for further study of saline-brackish water sedimentary environment shales in the Junggar Basin.
