渤海湾油型盆地深层大型气藏成藏过程与相态控制因素  

Accumulation Process and Phase Control Factors of Large Natural Gas Reservoirs in the Oil⁃Prone Bohai Bay Basin,East China

作　　者：薛永安 胡安文 万琳 张鑫 Xue Yong’an;Hu Anwen;Wan Lin;Zhang Xin(Bohai Oilfield Research Institute,Tianjin Branch,CNOOC China Limited,Tianjin 300459,China)

机构地区：[1]中海石油(中国)有限公司天津分公司,天津300459

出　　处：《地球科学》2025年第2期377-387,共11页Earth Science

基　　金：“十四五”重大科技项目“潜山油气成藏理论与勘探关键技术”(No.KJGG2022-0302).

摘　　要：渤海湾油型盆地内近几年发现了多个大型气藏,其中渤中19-6构造天然气储量超千亿方,突破了油型盆地内难以找到大型气藏的传统认识.综合应用油气组分、天然气同位素、流体包裹体和PVT分析数据等分析了渤海湾油型盆地大型气藏成藏过程与相态控制因素.研究结果表明:渤海湾油型盆地内已发现大型气藏普遍经历了“早油晚气”的成藏过程,CO_(2)受到幔源与壳源的共同影响,为壳幔混合成因;CO_(2)含量影响流体相态,表现为随含量增加体系临界温度降低而更易呈气相,高CO_(2)含量的古生界碳酸盐岩潜山为气藏,低CO_(2)含量的太古界潜山多为凝析气藏或高挥发性油藏.在上述认识指导下,应将寻找大型凝析气藏作为油型盆地内天然气藏勘探方向.In recent years,multiple large gas reservoirs have been discovered in the oil-prone Bohai Bay Basin,among which the natural gas reserves of the Bozhong 19-6 structure exceed 100 billion cubic meters,breaking the traditional understanding that large gas reservoirs cannot be found in oil-prone basins.This article comprehensively applies oil and gas components,natural gas isotopes,fluid inclusions,and PVT analysis data to analyze the formation process and phase control factors of large-scale gas reservoirs in the Bohai Bay oil type basin.The research results indicate that large gas reservoirs have been discovered in the Bohai Bay oil-bearing basin,and have generally undergone the process of"early oil and late gas"accumulation.CO_(2)is influenced by both mantle and crust sources,resulting in a mixed crust mantle origin;The CO_(2)content affects the fluid phase state,manifested as a decrease in the critical temperature of the system as the content increases,making it more prone to gas phase.High CO_(2)content Paleozoic carbonate buried hills are gas reservoirs,while low CO_(2)content Archean buried hills are mostly condensate gas reservoirs or high volatility oil reservoirs.Therefore,the search for large condensate gas reservoirs should be considered as the exploration direction for natural gas reservoirs in oil bearing basins.

关 键 词：大型气藏 成藏过程 二氧化碳 相态 渤海湾盆地 石油地质 

分 类 号：P618.13[天文地球—矿床学]