石油与天然气地质 ›› 2022, Vol. 43 ›› Issue (2): 341-352.doi: 10.11743/ogg20220208

• 油气地质 • 上一篇    下一篇

四川盆地川西气田中三叠统雷口坡组气藏气源再认识

苏成鹏1,2(), 何莹1,2(), 宋晓波2, 董波1, 吴小奇3   

  1. 1.中国石化 西南油气分公司 彭州气田(海相)开发项目部,四川 彭州 611930
    2.中国石化 西南油气分公司 勘探开发研究院,四川 成都 610041
    3.中国石化 石油勘探开发研究院,四川 成都 610041
  • 收稿日期:2020-12-14 修回日期:2022-01-22 出版日期:2022-04-01 发布日期:2022-03-11
  • 通讯作者: 何莹 E-mail:suchengpeng90@163.com;heywz@126.com
  • 第一作者简介:苏成鹏(1990—),男,博士、助理研究员,碳酸盐岩天然气地质。E?mail: suchengpeng90@163.com
  • 基金项目:
    中国石化科技攻关项目(P20059-3);国家自然科学基金项目(41872122)

Reinterpretation of gas sources in the Middle Triassic Leikoupo Formation in Western Sichuan gas field, Sichuan Basin

Chengpeng Su1,2(), Ying He1,2(), Xiaobo Song2, Bo Dong1, Xiaoqi Wu3   

  1. 1.Development Project Department of Pengzhou Gas Field (Marine Facies),Southwest Oil and Gas Branch of SINOPEC,Pengzhou,Sichuan 611930,China
    2.Research Institute of Exploration and Development,Southwest Branch of SINOPEC,Chengdu,Sichuan 610041,China
    3.Research Institute of Petroleum Exploration and Production,SINOPEC,Chengdu,Sichuan 610041,China
  • Received:2020-12-14 Revised:2022-01-22 Online:2022-04-01 Published:2022-03-11
  • Contact: Ying He E-mail:suchengpeng90@163.com;heywz@126.com

摘要:

天然气探明储量超千亿立方米的川西气田是中国石化继普光和元坝气田之后,在四川盆地发现的第3个大型海相气田。目前对该气田中三叠统雷口坡组气藏的气源认识尚未统一,争议较大,有必要对其开展再分析。对川西气田不同构造雷口坡组四段三亚段(雷四三亚段)上、下产层的天然气组分和烷烃同位素特征分析表明,川西气田同一构造雷四三亚段下储层气藏和上储层气藏具有相同的气源,而不同构造间气源具有差异。其中,石羊场构造和鸭子河构造天然气中H2S和CO2含量高、δ13C2 偏轻(均值-32.5‰),以及烷烃气碳同位素倒转,表现出典型的油型气特征;金马构造天然气中H2S和CO2含量相对较低、δ13C2 偏重(均值-27.5‰),以及烷烃气碳同位素正序分布,表现出混源气特征。此外,基于研究区天然气运移条件分析,结合前人研究成果认为,川西气田石羊场构造和鸭子河构造天然气主要来自雷口坡组自身烃源岩,而金马构造天然气则主要来自雷口坡组烃源岩和上二叠统龙潭组烃源岩,但不排除上三叠统马鞍塘组-小塘子组烃源岩对其有少许贡献。

关键词: 天然气组分, 烷烃同位素, 运移条件, 构造差异, 天然气藏, 雷口坡组, 川西坳陷, 四川盆地

Abstract:

The Western Sichuan gas field with proven geologic reserves of over 1 000 × 108 m3 of natural gas ranks third in scale in the Sichuan Basin following Puguang and Yuanba gas fields. Recently, there have been some controversies regarding to the sources of gas in the Leikoupo reservoir, rendering the necessity to make further analysis. The natural gas in the upper and lower pay zones in the 3rd submember of the 4th member of Leikoupo Formation (hereinafter referred to as Lei 43) in different structures is analyzed for natural gas components and alkane isotopic compositions, which indicate that the lower and upper gas reservoirs in the Lei 43 shale the same gas source. While the gas sources vary with structural belts. Natural gas from Shiyang and Yazihe structural belts, is characterized by high content of H2S and CO2, low δ13C2 (mean: -32.5 ‰), and carbon isotope reversal of alkane, typical of oil-derived gas. However, in the Jinma Structure, the natural gas features relatively low content of H2S and CO2, high δ13C2 (mean: -27.5 ‰), and normal carbon isotope sequence pattern, showing the characteristics of mixed gas. In addition, based on the analysis of gas-migration conditions and previous studies, we consider that the natural gas in the Shiyangchang and Yazihe structural belts is mainly derived from the Leikoupo source rocks, and that in the Jinma structural belt mainly derived from the source rocks of Leikoupo and the Permian Longtan Formations, though without excluding minor contributions by the Ma'antang-Xiaotangzi source rocks.

Key words: natural gas composition, alkane isotope, migration condition, structural difference, gas reservoir, Leikoupo Formation, Western Sichuan Depression, Sichuan Basin

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