Owing to the characteristics of chemical inertness,low molecular weight,low boiling point,strong permeability and high heat conductivity,helium is extensively used in the fields of aerospace,low-temperature supercondu...Owing to the characteristics of chemical inertness,low molecular weight,low boiling point,strong permeability and high heat conductivity,helium is extensively used in the fields of aerospace,low-temperature superconductivity,medicine and high tech,and it is a kind of irreplaceable strategic rare resource.So far,however,less research has been conducted on the enrichment of helium in natural gas reservoirs.To solve this problem,this paper discusses the classification standard of helium-rich gas reservoirs.Based on this,the origin,source and enrichment process of helium in typical helium-rich gas reservoirs are studied,highlighting the contribution of main helium sources to helium-rich gas reservoirs.In addition,helium enrichment models of helium-rich gas reservoir in petroliferous basins are established.And the following research results are obtained.First,6 helium enrichment models of two categories(crust-source helium enrichment and crust-mantle mixing helium enrichment)are established for different petroliferous basins in China.Second,helium-rich gas reservoirs are characterized by using the multiple helium supply and diverse helium enrichment model.And no matter what enrichment model it is,the contribution of the main helium source to gas reservoirs is indispensable.Third,the helium in the gas reservoirs of central and western basins is mainly crust-source helium,and its enrichment models include ancient formation water moving upward along the fault to dilute helium,helium enrichment in the process of natural gas migration along ancient reservoirs,and helium enrichment of shale gas.Fourth,the helium in the helium-rich gas reservoirs of eastern basins is of crust-mantle mixing origin and its enrichment models are mainly hydrocarbon gas based,carbon dioxide based and nitrogen based.In conclusion,the establishment of the helium enrichment models of helium-rich gas reservoirs in petroliferous basins provides reference and guidance for studying helium enrichment laws and main controlling factors and is of great significance to the evaluation of favorable helium exploration areas.展开更多
Taking the natural gas reservoirs of the Sinian Dengying Formation on the east and west sides(Gaoshiti-Moxi area and north slope of central Sichuan paleo-uplift on the east;Weiyuan and Well Datan-1 block on the west)o...Taking the natural gas reservoirs of the Sinian Dengying Formation on the east and west sides(Gaoshiti-Moxi area and north slope of central Sichuan paleo-uplift on the east;Weiyuan and Well Datan-1 block on the west)of the Deyang-Anyue rift trough in the Sichuan Basin,China,as the research object,the geochemical parameters(component,isotopic composition)of natural gas from the Dengying Formation in different areas are compared,and then the differences in geochemical characteristics of Dengying natural gas on the east and west sides of the Deyang-Anyue rift trough and their genesis are clarified.First,the Dengying gas reservoirs on both sides of the rift trough are predominantly composed of oil-cracking gas with high maturity,which is typical dry gas.Second,severely modified by thermochemical sulfate reduction(TSR)reaction,the Dengying gas reservoirs on the east side exhibit high H2S and CO_(2) contents,with an elevated δ^(13)C_(2) value(average value higher than-29‰).The Dengying gas reservoirs in the Weiyuan area are less affected by TSR modification,though the δ^(13)C_(1) values are slightly greater than that of the reservoirs on the east side with partial reversal of carbon isotope composition,likely due to the water-soluble gas precipitation and accumulation mechanism.The Dengying gas reservoir of Well Datan-1 shows no influence from TSR.Third,the Dengying gas reservoirs reflect high helium contents(significantly higher than that on the east side)in the Weiyuan and Datan-1 areas on the west side,which is supposed to attribute to the widespread granites in basement and efficient vertical transport along faults.Fourth,controlled by the paleo-salinity of water medium in the depositional period of the source rock,the δ^(2)HCH_(4) values of the Dengying gas reservoirs on the west side are slightly lighter than those on the east side.Fifth,the Dengying natural gas in the Datan-1 area is contributed by the source rocks of the Sinian Doushantuo Formation and the third member of the Dengying Formation,in addition to the Cambrian Qiongzhusi Formation.展开更多
基金supported by the National Natural Science Foundation of China“Water-soluble gas accumulation and its quantitative research method based on rare gas tracking”(No.41872162)the National Natural Science Foundation of China“Enrichment mechanism and resource potential of helium in superimposed basins in central-western China”(No.42141022).
文摘Owing to the characteristics of chemical inertness,low molecular weight,low boiling point,strong permeability and high heat conductivity,helium is extensively used in the fields of aerospace,low-temperature superconductivity,medicine and high tech,and it is a kind of irreplaceable strategic rare resource.So far,however,less research has been conducted on the enrichment of helium in natural gas reservoirs.To solve this problem,this paper discusses the classification standard of helium-rich gas reservoirs.Based on this,the origin,source and enrichment process of helium in typical helium-rich gas reservoirs are studied,highlighting the contribution of main helium sources to helium-rich gas reservoirs.In addition,helium enrichment models of helium-rich gas reservoir in petroliferous basins are established.And the following research results are obtained.First,6 helium enrichment models of two categories(crust-source helium enrichment and crust-mantle mixing helium enrichment)are established for different petroliferous basins in China.Second,helium-rich gas reservoirs are characterized by using the multiple helium supply and diverse helium enrichment model.And no matter what enrichment model it is,the contribution of the main helium source to gas reservoirs is indispensable.Third,the helium in the gas reservoirs of central and western basins is mainly crust-source helium,and its enrichment models include ancient formation water moving upward along the fault to dilute helium,helium enrichment in the process of natural gas migration along ancient reservoirs,and helium enrichment of shale gas.Fourth,the helium in the helium-rich gas reservoirs of eastern basins is of crust-mantle mixing origin and its enrichment models are mainly hydrocarbon gas based,carbon dioxide based and nitrogen based.In conclusion,the establishment of the helium enrichment models of helium-rich gas reservoirs in petroliferous basins provides reference and guidance for studying helium enrichment laws and main controlling factors and is of great significance to the evaluation of favorable helium exploration areas.
基金Supported by the National Natural Science Foundation of China(42272161)PetroChina Science and Technology Major Project(2023ZZ16)Research Institute of Exploration and Development,PetroChina Southwest Oil&Gasfield Company(2024D101-01-06)。
文摘Taking the natural gas reservoirs of the Sinian Dengying Formation on the east and west sides(Gaoshiti-Moxi area and north slope of central Sichuan paleo-uplift on the east;Weiyuan and Well Datan-1 block on the west)of the Deyang-Anyue rift trough in the Sichuan Basin,China,as the research object,the geochemical parameters(component,isotopic composition)of natural gas from the Dengying Formation in different areas are compared,and then the differences in geochemical characteristics of Dengying natural gas on the east and west sides of the Deyang-Anyue rift trough and their genesis are clarified.First,the Dengying gas reservoirs on both sides of the rift trough are predominantly composed of oil-cracking gas with high maturity,which is typical dry gas.Second,severely modified by thermochemical sulfate reduction(TSR)reaction,the Dengying gas reservoirs on the east side exhibit high H2S and CO_(2) contents,with an elevated δ^(13)C_(2) value(average value higher than-29‰).The Dengying gas reservoirs in the Weiyuan area are less affected by TSR modification,though the δ^(13)C_(1) values are slightly greater than that of the reservoirs on the east side with partial reversal of carbon isotope composition,likely due to the water-soluble gas precipitation and accumulation mechanism.The Dengying gas reservoir of Well Datan-1 shows no influence from TSR.Third,the Dengying gas reservoirs reflect high helium contents(significantly higher than that on the east side)in the Weiyuan and Datan-1 areas on the west side,which is supposed to attribute to the widespread granites in basement and efficient vertical transport along faults.Fourth,controlled by the paleo-salinity of water medium in the depositional period of the source rock,the δ^(2)HCH_(4) values of the Dengying gas reservoirs on the west side are slightly lighter than those on the east side.Fifth,the Dengying natural gas in the Datan-1 area is contributed by the source rocks of the Sinian Doushantuo Formation and the third member of the Dengying Formation,in addition to the Cambrian Qiongzhusi Formation.
