四川盆地蓬莱气区上二叠统长兴组凝析油成因及其油气地质意义  

Condensate oil in the Upper Permian Changxing Formation in Penglai gas area,Sichuan Basin:Genesis and its geological implications

作　　者：文龙 罗冰[2] 谢增业[3,4] 张本健[2] 武赛军[3] 张斌[3] 谢武仁[3] 陈骁[2] 刘博文[5] 崔会英[3,4] 孙豪飞[2] 冉钰 国建英[3,4] 明盈 徐亮[2] 陈大伟 WEN Long;LUO Bing;XIE Zengye;ZHANG Benjian;WU Saijun;ZHANG Bin;XIE Wuren;CHEN Xiao;LIU Bowen;CUI Huiying;SUN Haofei;RAN Yu;GUO Jianying;MING Ying;XU Liang;CHEN Dawei(PetroChima Southwest Oil&Gasfield Company,Chengdu,Sichuan 610051,China;Exploration and Development Research Institute,PetroChima Southwest Oil&Gafield Company,Chengdu,Sichuan 610051,China;PetroChina Research Institute of Petroleum Exploration&Development,Beijing 100083,China;CNPC Key Laboratory of Gas Reservoir Formation and Development,Langfang,Hebei 065007,China;Central Sichuan Oil&Gas District,PetroChima Southwest Oil&Gasfield Company,Suining,Sichuan 629000,China)

机构地区：[1]中国石油西南油气田公司,四川省成都市610051 [2]中国石油西南油气田公司勘探开发研究院 [3]中国石油勘探开发研究院 [4]中国石油天然气集团公司天然气成藏与开发重点实验室,河北省廊坊市065007 [5]中国石油西南油气田公司川中油气矿

出　　处：《天然气工业》2025年第2期1-13,共13页Natural Gas Industry

基　　金：中国石油天然气股份有限公司科研项目“大气田(区)成藏规律与勘探关键技术研究”(编号:2021DJ0602);中国石油天然气集团有限公司科技项目“中国石油重点地区风险勘探目标研究”(编号:2023YQX10101);中国石油西南油气田公司科研项目“蓬溪—武胜浅水陆棚及其周缘长兴组成藏条件及油气富集规律研究”(编号:RIPRD-2023-JS-2453)。

摘　　要：四川盆地蓬莱气区蓬深10井在上二叠统长兴组发现凝析油,拓展了四川盆地液态烃保存的深度下限,亟需明确其成因及其油气地质意义。为此,应用原油碳同位素、轻烃、全油色谱、金刚烷、全二维气相色谱、芳烃色质等地球化学分析测试资料,结合研究区地质背景及烃源岩相关研究成果,明确了凝析油的地球化学特征及成因。研究结果表明:①长兴组凝析油成熟度为1.59%~1.75%,金刚烷指数和甲基菲指数等参数均揭示凝析油处于高成熟热演化阶段。②长兴组凝析油主要源于龙潭组煤系烃源岩;凝析油以环烷烃和芳烃化合物为主,芳烃化合物中联苯系列化合物含量达48.6%;凝析油全油碳同位素偏高(-26.4‰),与龙潭组干酪根碳同位素相似;类异戊二烯烷烃中姥鲛烷占优势,Pr/Ph值为1.73~1.85,凝析油烃源岩沉积于弱氧化沉积环境。③地质历史中未达到液态烃类完全裂解的温度、硫酸盐热化学还原反应改造强度弱以及异常超高压的共同作用是凝析油得以保存的主要原因。结论认为,长兴组凝析油为上二叠统龙潭组煤系烃源岩在高成熟阶段的产物,在龙潭组/吴家坪组烃源岩发育且后期未遭受TSR强烈改造的区域有望发现更多的长兴组凝析油;该研究认识为在四川盆地继续寻找长兴组凝析油提供了重要依据。Well PS-10 in the Penglai gas area of the Sichuan Basin revealed condensate oil from the Upper Permian Changxing Formation,which extended the lower depth limit of liquid hydrocarbon preservation in the basin.It is urgent to identify the genesis and its geological implications of such condensate oil.The geochemical characteristics and genesis of condensate oil are determined by using the data of geochemical analysis/test of carbon isotope,light hydrocarbon,whole oil chromatography,adamantane,two-dimensional gas chromatography and aromatics,combined with the geological setting and relevant researches on source rocks in the study area.The results are obtained in three aspects.First,Changxing Formation condensate oil corresponds to a maturity of 1.59%–1.75%,and in a high maturity stage depending on the parameters such as adamantane index and methylphenanthrene index.Second,Changxing Formation condensate oil derives from the coal-measure source rocks of the Longtan Formation.It is mainly composed of cycloalkane and aromatic compounds.The content of biphenyl series compounds in the aromatic compounds reaches 48.6%.The full-oil carbon isotope is relatively high(-26.4‰),which is similar to that of the kerogen of the Longtan Formation.Among the isoprenoid alkanes,pristane is dominant,and the Pr/Ph ratio is 1.73–1.85,suggesting that the source rock is deposited in a weak oxidation environment.Third,preservation of condensate oil in the geological history is attributed to the non-approach to the temperature for complete pyrolysis of liquid hydrocarbons,weak modification by thermochemical sulphate reduction(TSR),and abnormal ultra-high pressure.The conclusion is that Changxing Formation condensate oil is the product of the Upper Permian Longtan Formation coal-measure source rock in a high maturity stage,and more Longxing Formation condensate oil is expected to be found in areas where Longtan/Wujiaping Formation source rocks develop and awere not modified by late intense TSR.These research findings provide important evi

关 键 词：四川盆地 蓬莱气区 长兴组 凝析油 碳同位素 异常高压 深度下限 

分 类 号：TE122.111[石油与天然气工程—油气勘探]