石油学报 ›› 2016, Vol. 37 ›› Issue (12): 1463-1471.DOI: 10.7623/syxb201612002

• 地质勘探 • 上一篇    下一篇

油型气乙烷碳同位素演化规律与成因

吴伟, 罗超, 张鉴, 刘文平   

  1. 中国石油西南油气田公司勘探开发研究院 四川成都 610041
  • 收稿日期:2016-04-13 修回日期:2016-09-29 出版日期:2016-12-25 发布日期:2017-01-06
  • 通讯作者: 吴伟,男,1987年9月生,2009年获中国石油大学(华东)资源勘查工程专业学士学位,2015年获中国石油勘探开发研究院矿产普查与勘探专业博士学位,现为中国石油西南油气田公司勘探开发研究院页岩气研究中心工程师,主要从事天然气地质与地球化学方面的研究工作。Email:wuwei06@petrochina.com.cn
  • 作者简介:吴伟,男,1987年9月生,2009年获中国石油大学(华东)资源勘查工程专业学士学位,2015年获中国石油勘探开发研究院矿产普查与勘探专业博士学位,现为中国石油西南油气田公司勘探开发研究院页岩气研究中心工程师,主要从事天然气地质与地球化学方面的研究工作。Email:wuwei06@petrochina.com.cn
  • 基金资助:

    四川省科技支撑计划项目“四川盆地下古生界页岩气资源潜力评价及选区”(2015SZ0001)、中国科学院战略性先导科技专项(B类)“页岩气可采性地质评价方法”(XDB10010504)资助。

Evolution law and genesis of ethane carbon isotope of oil type gas

Wu Wei, Luo Chao, Zhang Jian, Liu Wenping   

  1. Exploration and Development Research Institute, PetroChina Southwest Oil & Gasfield Company, Sichuan Chengdu 610041, China
  • Received:2016-04-13 Revised:2016-09-29 Online:2016-12-25 Published:2017-01-06

摘要:

通过分析四川盆地和北美Appalachian、Fort Worth等盆地页岩气和常规油型气乙烷碳同位素特征和成因,得出随着成熟度的增加,乙烷碳同位素经历3个演化阶段:初次生气阶段正常增加,与甲烷碳同位素具有线性相关;二次裂解阶段同位素值减少,与乙烷含量的倒数具有线性关系,符合二端元气混合模型;湿气裂解阶段碳同位素值增加,与乙烷含量的自然对数呈线性关系,符合瑞利分馏模型。不同阶段页岩气碳同位素倒转的成因不同,瑞利分馏阶段碳同位素分馏速率乙烷>丙烷,并且甲烷碳同位素发生次生变化是造成过成熟阶段页岩气碳同位素反序的原因。富12C的乙烷是四川盆地页岩气高产井的重要地球化学特征。对于成熟度Ro>2.2%的天然气,乙烷碳同位素用于气源鉴别需要用瑞利分馏的公式校正。

关键词: 碳同位素, 页岩气, 同位素倒转, 二次裂解, 湿气裂解

Abstract:

Based on analyzing the characteristics and genesis of ethane carbon isotope of shale gas and conventional oil type gas in Sichuan Basin, and the Appalachian Basin, Fort Worth Basin, and other basins in North America, it is believed that ethane carbon isotope will experiences 3 stages with increasing maturity. In the first gas generation stage, it increases normally with a linear correlation with methane carbon isotope; it decreases in the secondary cracking stage with a linear relation with the reciprocal of ethane content, which is in line with the two end-member gas mixed model; it increases in the wet gas cracking stage with a linear relation with the natural logarithm of ethane content, which is in accordance with the Rayleigh fractional model. The genesis for carbon isotope reversal of shale gas varies in different stages. The fractionation rate of ethane carbon isotope is greater than that of propane carbon isotope in the Rayleigh fractional stage, and the secondary change of methane carbon isotope is a reason for the carbon isotope reverse order of shale gas in the overmature stage. 12C-rich ethane is an important geochemical characteristic of high-productivity shale gas well in Sichuan Basin. For natural gas with Ro>2.2%, ethane carbon isotope can be used to identify gas source after the correction using Rayleigh fractional formula.

Key words: carbon isotope, shale gas, isotope reversal, secondary cracking, wet gas cracking

中图分类号: