The prediction of sandstone distribution is the main target for hydrocarbon exploration and petroleum reservoir engineering,especially in a rift basin with a complex geological setting.During the Middle Eocene,the Don...The prediction of sandstone distribution is the main target for hydrocarbon exploration and petroleum reservoir engineering,especially in a rift basin with a complex geological setting.During the Middle Eocene,the Dongying and Yong’an deltas converged in the Dongying depression of the Bohai Bay Basin,eastern China.So far,studies on the control of the existing syndepositional faults on the deltaic sandbodies of the two confluence deltas have been largely neglected.In this contribution,the sedimentary characteristics and spatial distribution of the two deltas,converging in the Dongying depression,were determined.In addition,the morphodynamic controlling factors of the deposits of the two deltas were identified based on core examination,log analysis,and seismic data analysis.During delta progradation,the sandbodies of the initially separated deltas were affected by the development of syndepositional tensional faults,which eventually also influenced the distribution of the sandstone reservoirs.The results of this study can not only be applied to petroleum reservoir engineering but also provide important new information for the studies on delta sandbody all over the world.展开更多
The characteristics of diagenetic minerals and their effects on reservoir quality of the tight sandstones of the Permian in Sulige gas field of the Ordos Basin were studied through observations on thin sections,scanni...The characteristics of diagenetic minerals and their effects on reservoir quality of the tight sandstones of the Permian in Sulige gas field of the Ordos Basin were studied through observations on thin sections,scanning electron microscopy,energy dispersive spectroscopy analysis and electron microprobe analysis.Diagenetic minerals in the Permian sandstones consist of illite,kaolinite,chlorite,siliceous and calcite cements.Large amounts of intercrystalline pores between kaolinite and illite provide channels for acidic fluids flow and thereby were conducive to the formation of clastic solution pores,intergranular solution pores and composite pores.Authigenic chlorite occurs in the form of three morphotypes as grain-coating,pore-lining and pore-filling.Grain-coating and pore-lining chlorite with different crystal shapes occur as coatings on the framework grains.Pore-filling chlorite precipitated as discrete flaky plates in pore spaces.Quartz microcrystals developed but quartz overgrowth did not develop because of the occurrence of porelining chlorite.This,in turn,led to the preservation of primary pores by occupying potential nucleation sites for quartz overgrowth and thereby preventing quartz microcrystals from merging into quartz overgrowth.This process is regarded as the most important for influencing the quality of the lithophysical properties.Calcite cement was mainly precipitated during a late diagenetic stage and has a negative effect on the reservoir quality.This study provides important insights into analyzing the relationship between diagenetic minerals and reservoir quality and the results are directly applicable to the exploration and development of tight sandstone reservoirs all over the world.展开更多
基金financially supported by the ChinaASEAN Maritime Cooperation Fund Project (No.12120100500017001)the Key R&D Plan of Shandong Province (No.2017CXGC1608)。
文摘The prediction of sandstone distribution is the main target for hydrocarbon exploration and petroleum reservoir engineering,especially in a rift basin with a complex geological setting.During the Middle Eocene,the Dongying and Yong’an deltas converged in the Dongying depression of the Bohai Bay Basin,eastern China.So far,studies on the control of the existing syndepositional faults on the deltaic sandbodies of the two confluence deltas have been largely neglected.In this contribution,the sedimentary characteristics and spatial distribution of the two deltas,converging in the Dongying depression,were determined.In addition,the morphodynamic controlling factors of the deposits of the two deltas were identified based on core examination,log analysis,and seismic data analysis.During delta progradation,the sandbodies of the initially separated deltas were affected by the development of syndepositional tensional faults,which eventually also influenced the distribution of the sandstone reservoirs.The results of this study can not only be applied to petroleum reservoir engineering but also provide important new information for the studies on delta sandbody all over the world.
基金supported by the National Natural Science Foundation of China(grant No.42172167)China-ASEAN(Association of Southeast Asian Nations)Maritime Cooperation Fund Project(grant No.12120100500017001)。
文摘The characteristics of diagenetic minerals and their effects on reservoir quality of the tight sandstones of the Permian in Sulige gas field of the Ordos Basin were studied through observations on thin sections,scanning electron microscopy,energy dispersive spectroscopy analysis and electron microprobe analysis.Diagenetic minerals in the Permian sandstones consist of illite,kaolinite,chlorite,siliceous and calcite cements.Large amounts of intercrystalline pores between kaolinite and illite provide channels for acidic fluids flow and thereby were conducive to the formation of clastic solution pores,intergranular solution pores and composite pores.Authigenic chlorite occurs in the form of three morphotypes as grain-coating,pore-lining and pore-filling.Grain-coating and pore-lining chlorite with different crystal shapes occur as coatings on the framework grains.Pore-filling chlorite precipitated as discrete flaky plates in pore spaces.Quartz microcrystals developed but quartz overgrowth did not develop because of the occurrence of porelining chlorite.This,in turn,led to the preservation of primary pores by occupying potential nucleation sites for quartz overgrowth and thereby preventing quartz microcrystals from merging into quartz overgrowth.This process is regarded as the most important for influencing the quality of the lithophysical properties.Calcite cement was mainly precipitated during a late diagenetic stage and has a negative effect on the reservoir quality.This study provides important insights into analyzing the relationship between diagenetic minerals and reservoir quality and the results are directly applicable to the exploration and development of tight sandstone reservoirs all over the world.
