During ancient times,human interest in naturally-occurring gases was religious,while it was scientific in the historical age and industrial in modern times.Gases were also utilized for practical purposes and more than...During ancient times,human interest in naturally-occurring gases was religious,while it was scientific in the historical age and industrial in modern times.Gases were also utilized for practical purposes and more than 3000 years before present day,Chinese populations made use of methane for salt extraction while in the 17th century it was observed that native Americans ignited methane seepages.The development of human thinking on gases followed the fundamental steps that characterized the natural sciences during the 18th century scientific revolution that was based on significant improvements in analytical methods.These improvements are still ongoing while present-day scientific publications evidence the spread of the field of interest and more cooperation with geophysical sciences to solve common interest problems.The existence of proper meetings and dedicated scientific journals confirms that gas geochemistry has ended this pioneering phase to enter a more mature condition.展开更多
Western Desert represents a major oil and gas province in Egypt producing more than 50%of the country’s oil production.Oil and gas blend occurs in most producing fields,however,the genetic link between gas and liquid...Western Desert represents a major oil and gas province in Egypt producing more than 50%of the country’s oil production.Oil and gas blend occurs in most producing fields,however,the genetic link between gas and liquid hydrocarbon phases are not well-constrained.Obayied sub-basin in the Western Desert where oil and gas phases coexist in the Middle Jurassic sandstones of the Khatatba Formation provides an ideal place to investigate the link between oil and gas generation.Geochemical analyses on rock samples(Rock–Eval pyrolysis,vitrinite reflectance,R_(o))and gases(molecular and isotopic composition)were conducted in order to identify the genetic characteristics of the hydrocarbon phases produced.Maturity-relevant parameters(Rock–Eval T_(max),vitrinite reflectance R_(o))elucidate that only Middle Jurassic Khatatba organofacies capable of generating wet and dry hydrocarbon gases.Additionally,the enrichment of C_(7)normal alkanes,mono-branched alkanes relative to polybranched components in the Obayied gases reflect their generation via cracking of oil.Basin modelling results confirm gas generation through both primary and secondary cracking.However,secondary cracking of liquid hydrocarbon phases is volumetrically more significant.Primary cracking of the Khatatba organofacies likely predate and catalyze the secondary cracking of the liquid phases and therefore the volume of generated gas increases incrementally eastward where both processes coexist.The present study highlights the significant role of secondary cracking in the generation and accumulation of huge gas accumulations in the basins containing oil-prone source intervals.展开更多
基金supported partially by the National Science and Technology Major Project of the Ministry of Science and Technology of China(Nos.2021YFA0719003,2019YFA0708501)funds from Chinese Academy of Sciences as a visiting professorship for senior international scientists(No.2018VMA0007)。
文摘During ancient times,human interest in naturally-occurring gases was religious,while it was scientific in the historical age and industrial in modern times.Gases were also utilized for practical purposes and more than 3000 years before present day,Chinese populations made use of methane for salt extraction while in the 17th century it was observed that native Americans ignited methane seepages.The development of human thinking on gases followed the fundamental steps that characterized the natural sciences during the 18th century scientific revolution that was based on significant improvements in analytical methods.These improvements are still ongoing while present-day scientific publications evidence the spread of the field of interest and more cooperation with geophysical sciences to solve common interest problems.The existence of proper meetings and dedicated scientific journals confirms that gas geochemistry has ended this pioneering phase to enter a more mature condition.
文摘Western Desert represents a major oil and gas province in Egypt producing more than 50%of the country’s oil production.Oil and gas blend occurs in most producing fields,however,the genetic link between gas and liquid hydrocarbon phases are not well-constrained.Obayied sub-basin in the Western Desert where oil and gas phases coexist in the Middle Jurassic sandstones of the Khatatba Formation provides an ideal place to investigate the link between oil and gas generation.Geochemical analyses on rock samples(Rock–Eval pyrolysis,vitrinite reflectance,R_(o))and gases(molecular and isotopic composition)were conducted in order to identify the genetic characteristics of the hydrocarbon phases produced.Maturity-relevant parameters(Rock–Eval T_(max),vitrinite reflectance R_(o))elucidate that only Middle Jurassic Khatatba organofacies capable of generating wet and dry hydrocarbon gases.Additionally,the enrichment of C_(7)normal alkanes,mono-branched alkanes relative to polybranched components in the Obayied gases reflect their generation via cracking of oil.Basin modelling results confirm gas generation through both primary and secondary cracking.However,secondary cracking of liquid hydrocarbon phases is volumetrically more significant.Primary cracking of the Khatatba organofacies likely predate and catalyze the secondary cracking of the liquid phases and therefore the volume of generated gas increases incrementally eastward where both processes coexist.The present study highlights the significant role of secondary cracking in the generation and accumulation of huge gas accumulations in the basins containing oil-prone source intervals.
