Turpan-Hami Basin is a major petroliferous basin in China. To date the natural gas exploration is concentrated in the Taibei sag. The origin and source of natural gas in the Taibei sag has long been controversial. To ...Turpan-Hami Basin is a major petroliferous basin in China. To date the natural gas exploration is concentrated in the Taibei sag. The origin and source of natural gas in the Taibei sag has long been controversial. To further investigate the origin and source of the natural gas in the Taibei sag, combined with previous studies and the local geological backgrounds, this study collected 23 gas samples from the Baka, Qiuling, Shanshan and Wenmi oil fields in the Taibei sag and analyzed the sample composition, stable carbon and hydrogen isotopes of all the gas samples. The results show that, gases from the four oil fields in the Taibei sag are dominated by hydrocarbon gas and belong to wet gas. Methane accounts for 65.84% to 97.94%, the content of heavy hydrocarbon (C2-5) can be up to 34.98%, while the content of nonhydrocarbon (CO2, N2) is trace. The δ13C1 value is –44.9‰ to –40.4‰,δ13C2 is –28.2‰ to –24.9‰,δ13C3 is –27.1‰ to –18.0‰ and δ13C4 is –26.7‰ to –22.1;while the variation of δD1 is not significant from –272‰ to –252‰,δD2 is –236‰ to –200‰ and δD3 is –222‰ to –174‰. Methane and its homologues (C2-5) are characterized by normal stable carbon and hydrogen isotopic distribution pattern, i.e., with the increase of carbon number, methane and its homologues become more and more enriched in 13C or D (δ13C1<δ13C2<δ13C3<δ13C4<δ13C5,δD1<δD2<δD3), which is consistent with the carbon and hydrogen isotopic features of typical thermogenic gas. All these results show that the natural gases in the four oil fields are coal-derived gas with low maturity (Ro averaged at 0.7%), and are sourced from the Middle-Lower Jurassic coal measure. The hydrogen isotopic data of natural gas are affected by both thermal maturity and the water medium of the environment where source rocks are formed. The hydrogen isotopic data indicate that the source rocks are formed in terrestrial limnetic facies with freshwater. Natural gases from Well Ba23 and Well Ke19 experienced biodegradation in the late stage.展开更多
为了深入分析吐哈盆地胜北洼陷七克台组二段致密油成藏条件与主控因素,有效促进致密油勘探,开展了岩心观察、薄片鉴定、扫描电镜观察、高压压汞和有机地球化学分析等研究。结果表明:①七克台组二段发育一套微咸水湖相低熟烃源岩,TOC质...为了深入分析吐哈盆地胜北洼陷七克台组二段致密油成藏条件与主控因素,有效促进致密油勘探,开展了岩心观察、薄片鉴定、扫描电镜观察、高压压汞和有机地球化学分析等研究。结果表明:①七克台组二段发育一套微咸水湖相低熟烃源岩,TOC质量分数平均值为1.78%,有机质以Ⅰ型和Ⅱ1型为主,烃源岩品质良好。②七克台组二段中部发育一套致密混积岩储层,孔隙度为2.6%~7.8%,渗透率普遍<1.0 m D,孔隙结构及连通性中等,允许流体流动的孔喉直径下限为50 nm,可动流体孔隙度下限为2.6%,致密油可动性较强。③优质烃源岩分布、油源断裂、有利沉积相带共同控制了致密油藏的分布,具有"自源供烃、断-缝输导、优势相带控藏"的特征,根据控藏要素可划分出2类致密油勘探有利区。该研究成果对促进吐哈盆地胜北洼陷致密油勘探具有指导意义。展开更多
基金Supported by the National Natural Science Foundation of China(41472120)China National Science and Technology Major Project(2016ZX05007-01)
文摘Turpan-Hami Basin is a major petroliferous basin in China. To date the natural gas exploration is concentrated in the Taibei sag. The origin and source of natural gas in the Taibei sag has long been controversial. To further investigate the origin and source of the natural gas in the Taibei sag, combined with previous studies and the local geological backgrounds, this study collected 23 gas samples from the Baka, Qiuling, Shanshan and Wenmi oil fields in the Taibei sag and analyzed the sample composition, stable carbon and hydrogen isotopes of all the gas samples. The results show that, gases from the four oil fields in the Taibei sag are dominated by hydrocarbon gas and belong to wet gas. Methane accounts for 65.84% to 97.94%, the content of heavy hydrocarbon (C2-5) can be up to 34.98%, while the content of nonhydrocarbon (CO2, N2) is trace. The δ13C1 value is –44.9‰ to –40.4‰,δ13C2 is –28.2‰ to –24.9‰,δ13C3 is –27.1‰ to –18.0‰ and δ13C4 is –26.7‰ to –22.1;while the variation of δD1 is not significant from –272‰ to –252‰,δD2 is –236‰ to –200‰ and δD3 is –222‰ to –174‰. Methane and its homologues (C2-5) are characterized by normal stable carbon and hydrogen isotopic distribution pattern, i.e., with the increase of carbon number, methane and its homologues become more and more enriched in 13C or D (δ13C1<δ13C2<δ13C3<δ13C4<δ13C5,δD1<δD2<δD3), which is consistent with the carbon and hydrogen isotopic features of typical thermogenic gas. All these results show that the natural gases in the four oil fields are coal-derived gas with low maturity (Ro averaged at 0.7%), and are sourced from the Middle-Lower Jurassic coal measure. The hydrogen isotopic data of natural gas are affected by both thermal maturity and the water medium of the environment where source rocks are formed. The hydrogen isotopic data indicate that the source rocks are formed in terrestrial limnetic facies with freshwater. Natural gases from Well Ba23 and Well Ke19 experienced biodegradation in the late stage.
文摘为了深入分析吐哈盆地胜北洼陷七克台组二段致密油成藏条件与主控因素,有效促进致密油勘探,开展了岩心观察、薄片鉴定、扫描电镜观察、高压压汞和有机地球化学分析等研究。结果表明:①七克台组二段发育一套微咸水湖相低熟烃源岩,TOC质量分数平均值为1.78%,有机质以Ⅰ型和Ⅱ1型为主,烃源岩品质良好。②七克台组二段中部发育一套致密混积岩储层,孔隙度为2.6%~7.8%,渗透率普遍<1.0 m D,孔隙结构及连通性中等,允许流体流动的孔喉直径下限为50 nm,可动流体孔隙度下限为2.6%,致密油可动性较强。③优质烃源岩分布、油源断裂、有利沉积相带共同控制了致密油藏的分布,具有"自源供烃、断-缝输导、优势相带控藏"的特征,根据控藏要素可划分出2类致密油勘探有利区。该研究成果对促进吐哈盆地胜北洼陷致密油勘探具有指导意义。
