碳氢同位素在天然气成因研究中的应用  

Application of carbon and hydrogen isotopes in the natural gas origin study

作　　者：倪云燕 张津川 姚立邈 董国梁 王圆 王力 陈建平[2] Yunyan NI;Jinchuan ZHANG;Limiao YAO;Guoliang DONG;Yuan WANG;Li WANG;Jianping CHEN(China University of Petroleum(Beijing),Beijing 102249,China;PetroChina Research Institute of Petroleum Exploration&Development,Beijing 100083,China)

机构地区：[1]中国石油大学(北京),北京102249 [2]中国石油勘探开发研究院,北京100083

出　　处：《天然气地球科学》2024年第11期1897-1909,共13页Natural Gas Geoscience

基　　金：黔科合战略找矿项目(编号:[2022]ZD005);中国石油科学研究与技术开发项目(编号:2021DJ5302,2021DJ0502)联合资助。

摘　　要：不同类型的天然气具有不同的碳氢同位素组成,因此,天然气碳氢同位素组成是天然气成因判识的重要指标之一。随着天然气勘探技术的不断发展和勘探数据的持续增长,对天然气成因与来源的认识也在不断加深,如何更新和验证现有数据,以确保天然气成因判识图版的适用性变得至关重要。综合分析了中国四川、塔里木、鄂尔多斯、吐哈、松辽、苏北、三水、柴达木、渤海湾等盆地以及北大西洋中脊Lost City等地区不同成因类型天然气的碳氢同位素特征与常用的碳氢同位素相关的成因鉴别图版,得到以下4点结论:①中国天然气甲烷碳同位素(δ^(13)C_(1))、乙烷碳同位素(δ^(13)C_(2))、丙烷碳同位素(^(13)C_(3))、丁烷碳同位素(δ^(13)C_(4))值分布范围分别为-89.4‰~-11.4‰(均值为-36.6‰)、-66.0‰~-17.5‰(均值为-29.4‰)、-49.5‰~-13.2‰(均值为-27.3‰)、-38.5‰~-16.0‰(均值为-25.6‰);②中国天然气甲烷氢同位素(δD_(1))、乙烷氢同位素(δD_(2))、丙烷氢同位素(δD_(3))值分布范围分别为-287‰~-111‰(均值为-177‰)、-249‰~-94‰(均值为-158‰)、-237‰~-75‰(均值为-146‰);③中国天然气甲烷及其同系物之间碳同位素和氢同位素以正序分布为主(δ^(13)C_(1)<δ^(13)C_(2)<δ^(13)C_(3)<δ^(13)C_(4),δD_(1)<δD_(2)<δD_(3)),且大部分天然气样品甲烷和乙烷之间的碳氢同位素分馏幅度大于乙烷和丙烷之间的碳氢同位素分馏幅度(Δ(δ^(13)C_(2)-δ^(13)C_(1))>Δ(δ^(13)C_(3)-δ^(13)C_(2)),Δ(δD_(2)-δD_(1))>Δ(δD_(3)-δD_(2)));④δ^(13)C_(1)—δ^(13)C_(2)—δ^(13)C_(3)图版、δ^(13)C_(1)—δD_(1)图版、δ^(13)C_(1)—C_(1)/C_(2+3)图版、Δ(δ^(13)C_(2)-δ^(13)C_(1))—Δ(δ^(13)C_(3)-δ^(13)C_(2))图版、Δ(δD_(2)-δD_(1))—Δ(δD_(3)-δD_(2))图版等都能对天然气进行一定程度的成因鉴别,不同图版之间的联合应用能够加强鉴别效果。Different types of natural gas have different carbon and hydrogen isotopic compositions,so the carbon and hydrogen isotopic composition of natural gas is one of the important indicators of natural gas origin identification.With the continuous development of natural gas exploration technology and the continuous growth of exploration data,understanding of the origin and source of natural gas is also deepening,and how to update and verify the existing data to ensure the applicability of natural gas genetic identification figure has become crucial.This study comprehensively analyzes the stable carbon and hydrogen isotope characteristics of different genetic types of natural gases in Sichuan,Tarim,Ordos,Turpan-Hami,Songliao,Northern Jiangsu,Sanshui,Qaidam,and Bohai Bay basins in China,together with abiotic gases from the Lost City of the Middle Atlantic Ridge,and the genetic identification diagrams related to commonly used carbon and hydrogen isotopes are evaluated.The following four conclusions are obtained:(1)The carbon isotopic values of methane(δ^(13)C_(1)),ethane(δ^(13)C_(2)),propane(δ^(13)C_(3))and butane(δ^(13)C_(4))of natural gases from China are from-89.4‰to-11.4‰(average of-36.6‰),-66.0‰to-17.5‰(average of-29.4‰),-49.5‰to-13.2‰(average of-27.3‰),-38.5‰to-16.0‰(average of-25.6‰),respectively.(2)The hydrogen isotopic values of methane(δD_(1)),ethane(δD_(2))and propane(δD_(3))of natural gases from China range from-287‰to-111‰(average of-177‰),-249‰to-94‰(average of-158‰),and-237‰to-75‰(average of-146‰),respectively.(3)The carbon and hydrogen isotopic distribution patterns among methane and its homologues of natural gases in China are mainly in positive order(δ^(13)C_(1)<δ^(13)C_(2)<δ^(13)C_(3)<δ^(13)C_(4),δD_(1)<δD_(2)<δD_(3)).The fractionation amplitude between methane and ethane is greater than that between ethane and propane(Δ(δ^(13)C_(2)-δ^(13)C_(1))>Δ(δ^(13)C_(3)-δ^(13)C_(2)),Δ(δD_(2)-δD_(1))>Δ(δD_(3)-δD_(2)))in most natural gas samples.(4

关 键 词：天然气 碳同位素 氢同位素 成因鉴别 图版 

分 类 号：TE122.113[石油与天然气工程—油气勘探]