Organic-inorganic interactions between hydrocarbons and most minerals in deeply buried reservoirs remain unclear.In this study,gold capsules and fused silica capillary capsules(FSCCs)with different com-binations of nC...Organic-inorganic interactions between hydrocarbons and most minerals in deeply buried reservoirs remain unclear.In this study,gold capsules and fused silica capillary capsules(FSCCs)with different com-binations of nC_(16)H_(34),water(distilled water,CaCl_(2) water)and minerals(quartz,feldspar,calcite,kaolinite,smectite,and illite)were heated at 340℃ for 3-10 d,to investigate the evolution and reaction pathways of the organic-inorganic interactions in different hot systems.After heating,minerals exhibited little alteration in the anhydrous systems.Mineral alterations,how-ever,occurred obviously in the hydrous systems.Different inorganic components affected nC_(16)H_(34) degra-dation differently.Overall,water promoted the free-radical thermal-cracking reaction and step oxidation reaction but suppressed the free-radical cross-linking reaction.The impact of CaCl_(2) water on the nC_(16)H_(34) degradation was weaker than the distilled water as high Ca^(2+)concentration suppressed the formation of free radicals.The presence of different waters also affects the impact of different minerals on nC_(16)H_(34) degradation,via its impact on mineral alterations.In the anhydrous nC_(16)H_(34)-mineral systems,calcite and clays catalyzed generation of low-molecular-weight(LMW)alkanes,particularly the clays.Quartz,feldspar,and calcite catalyzed generation of high-molecular-weight(HMW)alkanes and PAHs,whereas clays catalyzed the generation of LMW alkanes and mono-bicyclic aromatic hydrocarbons(M-BAHs).In the hydrous nC_(16)H_(34)-distilled water-mineral systems,all minerals but quartz promoted nC_(16)H_(34) degra-dation to generate more LMW alkanes,less HMW alkanes and PAHs.In the nC_(16)H_(34)-CaCl_(2) water-mineral systems,the promotion impact of minerals was weaker than that in the systems with distilled water.This study demonstrated the generation of different hydrocarbons with different fluorescence colors in the different nC_(16)H_(34)-water-mineral systems after heating for the same time,implying that fluorescence colors need to be interpreted carefully in investigation of hydrocarbon charging histories and oil origins in deeply buried reservoirs.Besides,the organic-inorganic interactions in different nC_(16)H_(34)-water-mineral systems proceeded in different pathways at different rates,which likely led to preservation of liquid hydrocarbons at different depth(temperature).Thus,quantitative investigations of the reaction kinetics in different hydrocarbon-water-rock systems are required to improve the prediction of hydrocar-bon evolution in deeply buried hydrocarbon reservoirs.展开更多
Marine shale gas resources have great potential in the south of the Sichuan Basin in China.At present,the high-quality shale gas resources at depth of 2000–3500 m are under effective development,and strategic breakth...Marine shale gas resources have great potential in the south of the Sichuan Basin in China.At present,the high-quality shale gas resources at depth of 2000–3500 m are under effective development,and strategic breakthroughs have been made in deeper shale gas resources at depth of 3500–4500 m.To promote the effective production of shale gas in this area,this study examines key factors controlling high shale gas production and presents the next exploration direction in the southern Sichuan Basin based on summarizing the geological understandings from the Lower Silurian Longmaxi Formation shale gas exploration combined with the latest results of geological evaluation.The results show that:(1)The relative sea depth in marine shelf sedimentary environment controls the development and distribution of reservoirs.In the relatively deep water area in deep-water shelf,grade-I reservoirs with a larger continuous thickness develop.The relative depth of sea in marine shelf sedimentary environment can be determined by redox conditions.The research shows that the uranium to thorium mass ratio greater than 1.25 indicates relatively deep water in anoxic reduction environment,and the uranium to thorium mass ratio of 0.75–1.25 indicates semi-deep water in weak reduction and weak oxidation environment,and the uranium to thorium mass ratio less than 0.75 indicates relatively shallow water in strong oxidation environment.(2)The propped fractures in shale reservoirs subject to fracturing treatment are generally 10–12 m high,if grade-I reservoirs are more than 10 m in continuous thickness,then all the propped section would be high-quality reserves;in this case,the longer the continuous thickness of penetrated grade-I reservoirs,the higher the production will be.(3)The shale gas reservoirs at 3500–4500 m depth in southern Sichuan are characterized by high formation pressure,high pressure coefficient,well preserved pores,good pore structure and high proportion of free gas,making them the most favorable new field for shale gas exploration;and the pressure coefficient greater than 1.2 is a necessary condition for shale gas wells to obtain high production.(4)High production wells in the deep shale gas reservoirs are those in areas where Long11-Long13 sub-beds are more than 10 m thick,with 1500 m long horizontal section,grade-I reservoirs penetration rate of over 90%,and fractured by dense cutting+high intensity sand injection+large displacement+large liquid volume.(5)The relatively deep-water area in the deep-water shelf and the area at depth of 3500–4500 m well overlap in the southern Sichuan,and the overlapping area is the most favorable shale gas exploration and development zones in the southern Sichuan in the future.With advancement in theory and technology,annual shale gas production in the southern Sichuan is expected to reach 450×108 m3.展开更多
基金funded by the Natural Science Foundation of China Project(Grant Nos.41821002,41872140)the Special fund for Taishan Scholar Project(Grant No.tsqn201909061)the Fundamental Research Funds for the Central Universities(Grant No.20CX06067A)。
文摘Organic-inorganic interactions between hydrocarbons and most minerals in deeply buried reservoirs remain unclear.In this study,gold capsules and fused silica capillary capsules(FSCCs)with different com-binations of nC_(16)H_(34),water(distilled water,CaCl_(2) water)and minerals(quartz,feldspar,calcite,kaolinite,smectite,and illite)were heated at 340℃ for 3-10 d,to investigate the evolution and reaction pathways of the organic-inorganic interactions in different hot systems.After heating,minerals exhibited little alteration in the anhydrous systems.Mineral alterations,how-ever,occurred obviously in the hydrous systems.Different inorganic components affected nC_(16)H_(34) degra-dation differently.Overall,water promoted the free-radical thermal-cracking reaction and step oxidation reaction but suppressed the free-radical cross-linking reaction.The impact of CaCl_(2) water on the nC_(16)H_(34) degradation was weaker than the distilled water as high Ca^(2+)concentration suppressed the formation of free radicals.The presence of different waters also affects the impact of different minerals on nC_(16)H_(34) degradation,via its impact on mineral alterations.In the anhydrous nC_(16)H_(34)-mineral systems,calcite and clays catalyzed generation of low-molecular-weight(LMW)alkanes,particularly the clays.Quartz,feldspar,and calcite catalyzed generation of high-molecular-weight(HMW)alkanes and PAHs,whereas clays catalyzed the generation of LMW alkanes and mono-bicyclic aromatic hydrocarbons(M-BAHs).In the hydrous nC_(16)H_(34)-distilled water-mineral systems,all minerals but quartz promoted nC_(16)H_(34) degra-dation to generate more LMW alkanes,less HMW alkanes and PAHs.In the nC_(16)H_(34)-CaCl_(2) water-mineral systems,the promotion impact of minerals was weaker than that in the systems with distilled water.This study demonstrated the generation of different hydrocarbons with different fluorescence colors in the different nC_(16)H_(34)-water-mineral systems after heating for the same time,implying that fluorescence colors need to be interpreted carefully in investigation of hydrocarbon charging histories and oil origins in deeply buried reservoirs.Besides,the organic-inorganic interactions in different nC_(16)H_(34)-water-mineral systems proceeded in different pathways at different rates,which likely led to preservation of liquid hydrocarbons at different depth(temperature).Thus,quantitative investigations of the reaction kinetics in different hydrocarbon-water-rock systems are required to improve the prediction of hydrocar-bon evolution in deeply buried hydrocarbon reservoirs.
基金Supported by the China National Science and Technology Major Project(2016ZX05062)the PetroChina Science and Technology Major Project(2016E-0611)
文摘Marine shale gas resources have great potential in the south of the Sichuan Basin in China.At present,the high-quality shale gas resources at depth of 2000–3500 m are under effective development,and strategic breakthroughs have been made in deeper shale gas resources at depth of 3500–4500 m.To promote the effective production of shale gas in this area,this study examines key factors controlling high shale gas production and presents the next exploration direction in the southern Sichuan Basin based on summarizing the geological understandings from the Lower Silurian Longmaxi Formation shale gas exploration combined with the latest results of geological evaluation.The results show that:(1)The relative sea depth in marine shelf sedimentary environment controls the development and distribution of reservoirs.In the relatively deep water area in deep-water shelf,grade-I reservoirs with a larger continuous thickness develop.The relative depth of sea in marine shelf sedimentary environment can be determined by redox conditions.The research shows that the uranium to thorium mass ratio greater than 1.25 indicates relatively deep water in anoxic reduction environment,and the uranium to thorium mass ratio of 0.75–1.25 indicates semi-deep water in weak reduction and weak oxidation environment,and the uranium to thorium mass ratio less than 0.75 indicates relatively shallow water in strong oxidation environment.(2)The propped fractures in shale reservoirs subject to fracturing treatment are generally 10–12 m high,if grade-I reservoirs are more than 10 m in continuous thickness,then all the propped section would be high-quality reserves;in this case,the longer the continuous thickness of penetrated grade-I reservoirs,the higher the production will be.(3)The shale gas reservoirs at 3500–4500 m depth in southern Sichuan are characterized by high formation pressure,high pressure coefficient,well preserved pores,good pore structure and high proportion of free gas,making them the most favorable new field for shale gas exploration;and the pressure coefficient greater than 1.2 is a necessary condition for shale gas wells to obtain high production.(4)High production wells in the deep shale gas reservoirs are those in areas where Long11-Long13 sub-beds are more than 10 m thick,with 1500 m long horizontal section,grade-I reservoirs penetration rate of over 90%,and fractured by dense cutting+high intensity sand injection+large displacement+large liquid volume.(5)The relatively deep-water area in the deep-water shelf and the area at depth of 3500–4500 m well overlap in the southern Sichuan,and the overlapping area is the most favorable shale gas exploration and development zones in the southern Sichuan in the future.With advancement in theory and technology,annual shale gas production in the southern Sichuan is expected to reach 450×108 m3.
