珠江口盆地惠州凹陷HZ21-1构造油气资源丰富,具有多源供烃、多层系含油的特点,油气成因来源有待进一步落实.天然气组分及碳同位素分析表明,该构造的气藏凝析气与油藏溶解气来自同一类烃源岩,其沉积母质以陆源有机质为主.气藏凝析油及油藏原油生物标志物特征分析表明,该构造下中新统珠江组上段高部位气藏凝析油气来源于惠州21洼恩平组及文昌组浅湖—沼泽相烃源岩,珠江组下段—恩平组油藏黑油主要来源于HZ26洼具有明显陆源有机质输入的文昌组半深—深湖相烃源岩,文昌组—古潜山油藏黑油来源于HZ26洼文昌组下段浅—半深湖相烃源岩,HZ21-1构造天然气的成藏早于油藏,凝析油气充注时间在中晚中新世.综合分析认为,HZ21-1构造具有断裂输导、下油上气的成藏模式,珠江组上段岩性尖灭圈闭及古潜山具有较大的滚动勘探潜力.%HZ21-1 structure in Huizhou sag of Pearl River Mouth basin is rich in both oil and gas resources which are extensively distributed in different formations and have multiple sources,but the hydrocarbon sources remain to be confirmed.Gas composition and carbon isotope analysis indicate that both condensate gas in gas reservoir and solution gas in oil reservoir in HZ21-1 structure are from the same source rocks characterized with dominant terrigenous parent organic matter.Oil biomarkers analysis indicates:condensate oil and gas in gas reservoirs in high part of N1 zjU is from shallow lacustrine to swamp source rocks of E2e and E2w in HZ21 subsag;black oil in oil reservoirs in N1 zjL—E2e is mainly from E2w semi-deep to deep lacustrine source rocks with significant terrigenous parent organic matters in HZ26 subsag;black oil in F2w ancient buried hill is from shallow to semi-deep lacustrine source rocks of E2wL;the forming of gas reservoir is earlier than that of oil reservoir in HZ21-1 structure,and the charging stage of condensate oil and gas is in the Middle-Late Miocene.Integrated analysis indicates that the HZ21-1 structure has the accumulation pattern of fault migration and gas-above and oil-low distribution.The lithologic pinch-out traps in N1 zjU and the buried hills have great potential for progressive exploration.
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