【作者】 曹军；

【导师】 罗小平；

【作者基本信息】 成都理工大学 ， 矿产普查与勘探， 2010， 硕士

【摘要】 通过对松南气田长岭断陷腰英台营城组火山岩岩性、岩相、储层物性、天然气地球化学特征及其天然气成因研究,得出以下几点认识:（1）该区营城组火山岩主要发育了8种岩性:流纹岩、气孔流纹岩、凝灰熔岩、晶屑玻屑凝灰岩、熔结凝灰岩、流纹质凝灰岩、角砾凝灰岩、火山角砾岩、原地火山角砾岩。其中,流纹岩是该区主要的火山岩岩类,其次是粗面岩和安山岩,总体表现为酸性喷出岩为主。（2）火山岩岩相具有纵向变化快,平面分布不稳定,以爆发相和喷溢相为主的特征。从火山岩的岩石学特征出发,结合前人在整个松辽盆地火山岩相的研究成果,在本区识别出了火山通道相、侵出相、爆发相、喷溢相、火山沉积相5大相,其喷发序列齐全,处于喷发的中心位置。由于其火山喷发形式为裂隙式喷发,各相、相内亚相发育不完全,该区主要发育爆发相热碎屑流亚相、热浪基亚相、空落亚相三个亚相,喷溢相上部亚相、中部亚相、下部亚相三个亚相,其发育特征完全。（3）该区孔隙类型主要发育气孔、溶孔、砾间（内）孔、微孔、构造缝、微裂缝,其储集类型主要为裂缝-孔隙型和孔隙型,其孔隙度平均为6.6%,渗透率平均为0.299 MD。爆发相中热碎屑流亚相孔隙度平均值仅为5.5%,渗透率0.068MD,喷溢相上部亚相孔隙度平均值达9.1%。在综合考虑火山岩岩性、岩相以及裂缝对储层空间的贡献情况下,认为喷溢相上部亚相发育的气孔流纹岩、碎裂的溶蚀角砾岩是储层的有利部位,而致密的熔结凝灰岩,流纹岩是裂缝发育的主要层段。（4）该区营城组天然气CH₄含量在70%左右,重烃中C₂H₆含量为0.51%～1.81%,C₃以后的重烃含量极少,天然气的干燥系数为0.97～0.99,表现为干气特征;天然气中的非烃气含量高,主要有CO₂与N₂,其中CO₂含量为20.74%～25.70%,N₂含量为3.73%～6.98%。营城组天然气组分甲烷碳同位素δ¹³C₁值皆大于-30‰,碳同位素呈负序列δC1>δC2>δC3>δC4或部分倒转现象。（5）对该区营城组火山岩天然气地球化学特征及成因分析认为,该区天然气具有δ¹³C₁值接近-20‰,甲烷同位素值偏重;天然气具有δ¹³C₁>δ¹³C₂>δ¹³C₃负序列或同位素倒转,表现具有无机幔源甲烷输入的特征;通过对不同端源甲烷同位素混合比例计算,认为腰英台营城组火山岩天然气中幔源甲烷比例较大,主要表现为无机成因甲烷气,其次是煤型气。天然气中CO₂、N₂等无机气体均来源于幔源气,因此该区天然气的成因具有“壳-幔”二元特征,为煤—幔混合气。更多还原

【Abstract】 Through the researches for Volcanic rocks lithology, lithofacies, property, natural gas geochemistry and genesis of natural gas of the Yingcheng formation in the Songnan gas field, we conclude the following points:（1） This Volcanic rocks area mainly developed 8 lithologies: stomatal rhyolite tuff lava, crystal glass dust tuff, welded tuff, rhyolitic tuff, tuff breccia, volcanic breccia, in-situ volcanic breccia. Of these, rhyolite is the major volcanic rocks in the area, followed by trachyte and andesite, the overall performance of mainly acidic extrusive rock.（2） The volcanic rocks phase are characteristics of Changes in the volcanic rocks with a vertical speed, horizontal distribution of instability and the main outbreak phase and effusive phase mainly. Based on Characteristics of volcanic rocks, combined with previous researches for the volcanic phase, we identified five major phases of the volcanic vent facies, intrusive facies, outbreak phase, effusive phase, volcanic sedimentary facies in the area, The eruption sequence is complete, at the center of the eruption. Because of its volcanic eruption in the form of fissure eruptions, each phase and subfacies development is not complete, this area mainly develop the pyroclastic flow facies, Nokia-phase heat and air off phase 3 sub-phases of the outbreak, facies upper, middle facies and lower subfacies three facies of effusive facies, the development features fully.（3） The main types of development of stomatal pore area, solution holes, gravel between the （internal） pore, porous, structural fractures, micro-cracks, the main types of reservoir are fractured-porous type and porous type, its average porosity was 6.6 % and permeability 0.299 MD. pyroclastic flow facies of outbreak phase average of only 5.5% porosity, permeability 0.068MD, the average porosity of the upper facies in effusive phase up to 9.1%. Comprehensive consideration of volcanic rocks lithology, lithofacies and reservoir space on the contribution of crack cases that effusive facies with upper rhyolite stomatal development, fragmentation of the dissolution breccia is better reservoir site, and The dense ignimbrite, rhyolite is the major layers of fracture development.（4） In Yingcheng formation, the CH4 gas content is about 70%, C₂H₆ heavy hydrocarbon content of 0.51%¹.81%, C₃ hydrocarbon content is extremely little, natural gas dry coefficient is 0.97 to 0.99, is characteristic with the dry gas features; non-hydrocarbon gas content in the natural gas is high, which mainly contain CO₂ and N₂, in which CO₂ content 20.74%²5.70%, N₂ content was 3.73%⁶.98%. In the Yingcheng formation, methane carbon isotopeδ¹³C₁ value are greater than -30‰, shows carbon isotope negative sequenceδ¹³C₁>δ¹³C₂>δ¹³C₃>δ¹³C₄ or part of the reverse phenomenon.（5） Through analysis the Volcanic gas geochemistry and genesis in the area ,we have made the conclusions: the value ofδ¹³C₁ is greater than -20‰, methane isotope emphasis on natural gas withδ¹³C₁>δ¹³C₂>δ¹³C₃ negative sequence or isotopes reverse, performance has inorganic mantle methane input features, the source of methane through the end of the isotope mixture of different proportion that Yaoyingtai Volcanic gas in a larger proportion of mantle-derived methane. CO₂, N₂ and other inorganic gases are derived from the mantle source gas, therefore, the cause of the natural gas in the area has a "crust - mantle" dual characteristics of coal - mantle mixture.更多还原