Based on the chemical and stable carbon isotopic composition of natural gas and light hydrocarbons, along with regional geological data, the genetic type, origin and migration of natural gases in the L lithologic gas ...Based on the chemical and stable carbon isotopic composition of natural gas and light hydrocarbons, along with regional geological data, the genetic type, origin and migration of natural gases in the L lithologic gas field, the eastern slope of Yinggehai Sag were investigated. The results show that these gases have a considerable variation in chemical composition, with 33.6%–91.5% hydrocarbon, 0.5%-62.2% CO2, and dryness coefficients ranging from 0.94 to 0.99. The alkane gases are characterized by δ13C1 values of -40.71‰--27.40‰,δ13C2 values of –27.27‰– –20.26‰, and the isoparaffin contents accounting for 55%–73% of the total C5–C7 light hydrocarbons. These data indicate that the natural gases belong to the coal-type gas and are mainly derived from the Miocene terrigenous organic-rich source rocks. When the CO2 contents are greater than 10%, the δ13CCO2 values are –9.04‰ to – 0.95‰ and the associated helium has a 3He/4He value of 7.78×10^–8, suggesting that the CO2 here is crustal origin and inorganic and mainly sourced from the thermal decomposition of calcareous mudstone and carbonate in deep strata. The gas migrated in three ways, i.e., migration of gas from the Miocene source rock to the reservoirs nearby;vertical migration of highly mature gas from deeper Meishan and Sanya Formations source rock through concealed faults;and lateral migration along permeable sandbodies. The relatively large pressure difference between the “source” and “reservoir” is the key driving force for the vertical and lateral migration of gas. Short-distance migration and effective “source - reservoir” match control the gas distribution.展开更多
Gas field water is the formation water produced together with natural gas in the process of natural gas exploitation.The gas field water treated is difficult to reach the standard due to its wide sources,numerous type...Gas field water is the formation water produced together with natural gas in the process of natural gas exploitation.The gas field water treated is difficult to reach the standard due to its wide sources,numerous types and complex composition.In addition,it can pollute soil,surface water and groundwater.In this study,the quality and pollution characteristics of gas field water in eastern Sichuan were studied by conventional water quality determination and GC-MS.The results show that the main components of gas field water in eastern Sichuan were chloride,COD Cr,SS,anionic surfactant,sulfide and other substances.The gas field water could be divided into two types according to the characteristics of water quality,of which one had high mineralization and high organic compounds,and the other had high sulfur and high organic compounds.There were 17 kinds of organic pollutants in the gas field water,mainly including alkanes,alcohols,esters and a small amount of acids.展开更多
基金Supported by the China National Science and Technology Major Project(2016ZX05024-005)
文摘Based on the chemical and stable carbon isotopic composition of natural gas and light hydrocarbons, along with regional geological data, the genetic type, origin and migration of natural gases in the L lithologic gas field, the eastern slope of Yinggehai Sag were investigated. The results show that these gases have a considerable variation in chemical composition, with 33.6%–91.5% hydrocarbon, 0.5%-62.2% CO2, and dryness coefficients ranging from 0.94 to 0.99. The alkane gases are characterized by δ13C1 values of -40.71‰--27.40‰,δ13C2 values of –27.27‰– –20.26‰, and the isoparaffin contents accounting for 55%–73% of the total C5–C7 light hydrocarbons. These data indicate that the natural gases belong to the coal-type gas and are mainly derived from the Miocene terrigenous organic-rich source rocks. When the CO2 contents are greater than 10%, the δ13CCO2 values are –9.04‰ to – 0.95‰ and the associated helium has a 3He/4He value of 7.78×10^–8, suggesting that the CO2 here is crustal origin and inorganic and mainly sourced from the thermal decomposition of calcareous mudstone and carbonate in deep strata. The gas migrated in three ways, i.e., migration of gas from the Miocene source rock to the reservoirs nearby;vertical migration of highly mature gas from deeper Meishan and Sanya Formations source rock through concealed faults;and lateral migration along permeable sandbodies. The relatively large pressure difference between the “source” and “reservoir” is the key driving force for the vertical and lateral migration of gas. Short-distance migration and effective “source - reservoir” match control the gas distribution.
文摘Gas field water is the formation water produced together with natural gas in the process of natural gas exploitation.The gas field water treated is difficult to reach the standard due to its wide sources,numerous types and complex composition.In addition,it can pollute soil,surface water and groundwater.In this study,the quality and pollution characteristics of gas field water in eastern Sichuan were studied by conventional water quality determination and GC-MS.The results show that the main components of gas field water in eastern Sichuan were chloride,COD Cr,SS,anionic surfactant,sulfide and other substances.The gas field water could be divided into two types according to the characteristics of water quality,of which one had high mineralization and high organic compounds,and the other had high sulfur and high organic compounds.There were 17 kinds of organic pollutants in the gas field water,mainly including alkanes,alcohols,esters and a small amount of acids.
