Abstract: To clarify the genesis and accumulation model of deep gas in Yingshan area of Songliao Basin, the geochemical characteristics and accumulation model of deep gas in Yingcheng Formation and Shahezi Formation were systematically analyzed based on the components and carbon isotope characteristics of gas as well as the pyrolysis, total organic carbon content and kerogen carbon isotope characteristics of source rocks. In Yingcheng Formation, oil-type gas mainly occurs, the source rocks are dominated by dark mudstone in Member 4 of Yingcheng Formation, the carbon isotopes of hydrocarbon components are relatively light, and the gas was accumulated in the late depositional period of Quantou Formation and Qingshankou Formation; in Shahezi Formation, only coal-type gas occurs, the carbon isotopes of the hydrocarbon components are relatively heavy, showing a positive sequence distribution on the whole, and the main hydrocarbon accumulation period is the late depositional period of Quantou Formation. In the late deposition period of the Quantou Formation, being mixed with coal-type gas from Shahezi Formation led to the reversal of δ¹³C₁＞δ¹³C₂ in some gas samples from Yingcheng Formation. The gas accumulation mode in Yingcheng Formation is characterized with near-source reservoirs, matched faults, and gas accumulation at the high point of structure; mudstones with high hydrocarbon-generating intensity control the distribution range of gas reservoirs; "uplift in sag" is the low potential zone for gas migration and the favorable directional zone for gas charging; the organic matching of "fault+trap" is the key to the formation of gas reservoirs. The tight gas accumulation mode in Shahezi Formation is characterized with integrated source and reservoir, overpressure driving, lateral near-source migration and accumulation; the macro distribution of gas reservoirs is controlled by the intensity of hydrocarbon expulsion from source rocks and overpressure range, while the gas reservoir scale is determined by the high-quality reservoir of "integrated migration and accumulation". The findings have important guidance and reference significance for deep gas exploration in the peripheral fault depression zone of Songliao Basin.

Key words: accumulation model, geochemical characteristics, carbon isotopes, Yingcheng Formation, Shahezi Formation, Yingshan area

摘要： 为明确 松辽盆地莺山地区深层天然气的成因与成藏模式,综合天然气组分及其碳同位素特征和烃源岩岩石热解、总有机碳含量和干酪根碳同位素特征等测试资料,系统分析了深层营城组和沙河子组天然气地球化学特征及其成藏模式。营城组天然气以油型气为主,烃源岩为营城组四段暗色泥岩,烃类组分的碳同位素偏轻,在泉头组沉积末期和青山口组沉积末期两期成藏;沙河子组天然气均为煤型气,烃类组分的碳同位素偏重,整体呈正序分布,主力成藏期为泉头组沉积末期。泉头组沉积末期,沙河子组煤型气的混入导致部分营城组天然气样品发生δ¹³C₁＞δ¹³C₂的倒转。营城组发育"源储紧邻、断体匹配、构造高点聚气"的天然气成藏模式,高生烃强度泥岩控制着气藏展布范围,"凹中隆"是天然气运移低势区和充注有利指向区,"断裂+圈闭"有机匹配是气藏形成的关键。沙河子组发育"源储一体、超压驱动、侧向近源运聚"的致密气成藏模式,烃源岩排烃强度和超压范围控制着气藏的宏观 展布,而"运聚一体"的优质储层决定了气藏规模。研究认识对于松辽盆地外围断陷区开展深层天然气勘探具有重要指导与借鉴意义。

关键词: 成藏模式, 地球化学特征, 碳同位素, 营城组, 沙河子组, 莺山地区