Despite over 40 years of exploration focusing on the deep to ultra-deep Ordovician carbonates as major hydrocarbon targets in the Tarim Basin,the identification of their source rocks remains elusive.Based on biomarker...Despite over 40 years of exploration focusing on the deep to ultra-deep Ordovician carbonates as major hydrocarbon targets in the Tarim Basin,the identification of their source rocks remains elusive.Based on biomarkers,carbon and sulfur isotopes of hydrocarbons,the primary source for the Ordovician petroleum system has been attributed mainly to the lower Cambrian shales,although some oils were likely contributed from the Lower Ordovician source rocks.However,the current understanding of the evolution of the Ordovician petroleum system remains rudimentary,largely due to the complex interplay of multi-source(i.e.,the widespread Precambrian shales)hydrocarbon inputs,diagenetic alterations,and tectonic processes over geological time.This study systematically investigates the molecular geochemistry of reservoir bitumen within the Ordovician carbonates from Tabei uplift,coupled with bitumen from the Sinian units at the western edge of the Tarim Basin.Our results indicate that the ion chromatography-mass spectrometry spectra and the saturated to aromatic hydrocarbons ratio of Ordovician reservoir bitumen closely resemble those of Sinian bitumen,as well as the published data of Sinian shales.This coupling linkage is revealed by cross-plots and ternary phase diagrams of various biomarker parameters,which can effectively distinguish the Sinian sources from other sources,i.e.,the Lower Cambrian and Ordovician,for the Ordovician reservoir bitumen.Specifically,the∑n-C_(21)-/∑n-C_(22)+,Pr/Ph,G/C_(31)H_(22)S,C_(23)/C_(21)TT ratios are effective indexes to differentiate these source rocks.By compiling the published organic geochemistry data of oils,it appears to infer that approximately 8.1%of the present-day oils produced from the Ordovician carbonates likely contain some proportion of Sinian-sourced oils.The recognition of Sinian sourced oils contributing to the paleo-and present-day Ordovician petroleum system offers valuable insights for the exploration of deep-ultra deep carbonates in the Tarim Basin,emphasizing the need to consider Precambrian shales as a significant hydrocarbon source.展开更多
The plane and profile geological models at the end of Neocene in the midwest of Tabei uplift are established on the basis of seismic data of oil field and tectonic analysis,and the numerical simulation results of tect...The plane and profile geological models at the end of Neocene in the midwest of Tabei uplift are established on the basis of seismic data of oil field and tectonic analysis,and the numerical simulation results of tectonic stress field in the area are obtained using linear elastic finite element method.Modeling results indicate that N-S regional compressive stress dominates the stress field of the whole area at that time,as well as that all faults of Yaha,Luntai,Hongqi,Yingmai 7 are compresso-shear structures with sinistral strike slip,while Kalayuergun fault is right lateral,and Yangtake fault is pure compressive thrust.In the condition of regional compressive stress,local stress field is formed,and affected by the main faults,which controlles the generation of secondary structures.In the modeling results of profile stress field,the orientation of the major principal stress change from horizon to incline in the middle of the uplifting area and the vertical stress component becomes bigger,which is the main factor to control the development of the compressional and subtuberant structures.展开更多
基金support by the Strategic Priority Research Program of Chinese Academy of Sciences(grant no.XDA0430202).
文摘Despite over 40 years of exploration focusing on the deep to ultra-deep Ordovician carbonates as major hydrocarbon targets in the Tarim Basin,the identification of their source rocks remains elusive.Based on biomarkers,carbon and sulfur isotopes of hydrocarbons,the primary source for the Ordovician petroleum system has been attributed mainly to the lower Cambrian shales,although some oils were likely contributed from the Lower Ordovician source rocks.However,the current understanding of the evolution of the Ordovician petroleum system remains rudimentary,largely due to the complex interplay of multi-source(i.e.,the widespread Precambrian shales)hydrocarbon inputs,diagenetic alterations,and tectonic processes over geological time.This study systematically investigates the molecular geochemistry of reservoir bitumen within the Ordovician carbonates from Tabei uplift,coupled with bitumen from the Sinian units at the western edge of the Tarim Basin.Our results indicate that the ion chromatography-mass spectrometry spectra and the saturated to aromatic hydrocarbons ratio of Ordovician reservoir bitumen closely resemble those of Sinian bitumen,as well as the published data of Sinian shales.This coupling linkage is revealed by cross-plots and ternary phase diagrams of various biomarker parameters,which can effectively distinguish the Sinian sources from other sources,i.e.,the Lower Cambrian and Ordovician,for the Ordovician reservoir bitumen.Specifically,the∑n-C_(21)-/∑n-C_(22)+,Pr/Ph,G/C_(31)H_(22)S,C_(23)/C_(21)TT ratios are effective indexes to differentiate these source rocks.By compiling the published organic geochemistry data of oils,it appears to infer that approximately 8.1%of the present-day oils produced from the Ordovician carbonates likely contain some proportion of Sinian-sourced oils.The recognition of Sinian sourced oils contributing to the paleo-and present-day Ordovician petroleum system offers valuable insights for the exploration of deep-ultra deep carbonates in the Tarim Basin,emphasizing the need to consider Precambrian shales as a significant hydrocarbon source.
文摘The plane and profile geological models at the end of Neocene in the midwest of Tabei uplift are established on the basis of seismic data of oil field and tectonic analysis,and the numerical simulation results of tectonic stress field in the area are obtained using linear elastic finite element method.Modeling results indicate that N-S regional compressive stress dominates the stress field of the whole area at that time,as well as that all faults of Yaha,Luntai,Hongqi,Yingmai 7 are compresso-shear structures with sinistral strike slip,while Kalayuergun fault is right lateral,and Yangtake fault is pure compressive thrust.In the condition of regional compressive stress,local stress field is formed,and affected by the main faults,which controlles the generation of secondary structures.In the modeling results of profile stress field,the orientation of the major principal stress change from horizon to incline in the middle of the uplifting area and the vertical stress component becomes bigger,which is the main factor to control the development of the compressional and subtuberant structures.
