川中地区侏罗系天然气与原油轻烃地球化学特征对比  

Light hydrocarbon characteristics of oil and gas in Jurassic reservoirs in the center of Sichuan Basin,China

作　　者：卢晓林[1] 李美俊[1,2] 王小娟 唐友军 韦腾强 何大祥 洪海涛 吴长江 冉子超 Xiao-lin LU;Mei-jun LI;Xiao-juan WANG;You-jun TANG;Teng-qiang WEI;Da-xiang HE;Hai-tao HONG;Chang-jiang WU;Zi-chao RAN(State Key Laboratory of Petroleum Resources and Prospecting,College of Geosciences,China University of Petroleum(Beijing),Beijing 102249,China;Key Laboratory of Exploration Technologies for Oil and Gas Resources,Ministry of Education,College of Resources and Environment,Yangtze University,Wuhan 430100,China;Exploration and Development Research Institute of Southwest Oil&Gas Field Company,PetroChina,Chengdu 610041,China)

机构地区：[1]油气资源与探测国家重点实验室,中国石油大学(北京)地球科学学院,北京102249 [2]油气资源与勘探技术教育部重点实验室,长江大学资源与环境学院,湖北武汉430100 [3]中国石油西南油气田公司勘探开发研究院,四川成都610041

出　　处：《天然气地球科学》2021年第7期1073-1083,共11页Natural Gas Geoscience

基　　金：国家自然科学基金(编号:41972148);国家科技重大专项(编号:2016ZX05004-005);油气资源与探测国家重点实验室开放基金(编号:PRP/open-1710)联合资助

摘　　要：天然气伴生凝析油及轻质油的轻烃地球化学参数常常被用于天然气成因和油—气对比研究,但蒸发分馏等次生作用对天然气和伴生原油的轻烃组成会产生一定的影响。基于川中地区16件侏罗系天然气与伴生凝析油或轻质油样品气相色谱分析,探讨了轻烃组成及相关地球化学参数在天然气和原油中的差异。研究表明:蒸发分馏作用对油气轻烃组成影响明显,相对于伴生原油,天然气轻烃组成具有高异构烷烃和正构烷烃相对含量,而贫环烷烃和芳香烃的特征。蒸发分馏作用对甲基环己烷指数、环己烷指数、Mango参数K1等成因参数影响不大,伴生原油的这类指标均可以较好地反映天然气的成因类型。蒸发分馏作用对成熟度参数异庚烷值影响较小,而对庚烷值、2,4-DMC5/2,3-DMC5值影响明显。轻烃化合物沸点的不同可能是导致天然气与原油中不同类型化合物相对含量存在差异的主要原因,并且沸点较低的化合物在天然气中相对含量更高。组成轻烃参数的化合物的沸点差异越大,该参数受蒸发分馏作用影响越大,天然气与伴生原油的该参数值相差也越显著。而当比值参数中组成分子与分母的化合物的沸点之差小于2℃时,该参数基本不受蒸发分馏作用的影响。The geochemical parameters relative to light hydrocarbons in natural gas and its associated condensate or light oil were frequently used in the investigation of the origin of natural gas and gas-oil correlation.However,the secondary alteration,such as evaporative fractionation effect may exert significant impact on the light hydrocarbon compositions of natural gas and its associated oil.Differences in light hydrocarbon compositions and values of related geochemical parameters between natural gas and relative crude oil were investigated on the basis of gas chromatography analyses of 16 gas samples and their associated condensates or light oils.The results show that evaporative fractionation has evident effect on the composition of light hydrocarbon.The relative abundance of iso-alkane and normal-alkanes in both oil type gas and coal type gas of Jurassic reservoirs in the study area is higher than that of associated oil.In contrast,the associated oil is more abundant in cycloalkane and aromatic hydrocarbon(benzene and toluene)than that of natural gas.Evaporative fractionation does not have much effect on the genetic type indicators,such as the MCH index(MCyC_(6)/(nC7+MCyC_(6)+1,1DMCyC_(5)+1,c3DMCyC_(5)+1,t3DMCyC_(5)+1,t2DMCyC_(5))×100),CH index(CyC_(6)/(nC_(6)+CyC_(6)+MCyC_(5))×100)and Mango’s LH parameter K1 value((2-MC_(6)+2,3-DMC_(5))/(3-MC_(6)+2,4-DMC_(5))).As for thermal maturity parameters,evaporative fractionation affects iso-heptane value slightly,but significantly on n-Heptane value and 2,4-DMP/2,3-DMP ratio.The difference of the boiling point of compounds may be the main reason for the difference of the relative contents of compounds in natural gas and oil.Moreover,compounds with lower boiling points are relatively more abundant in natural gas.The larger the difference of the boiling points of the compounds,the greater the influence of evaporative fractionation on the light hydrocarbon parameters.While,the parameters were almost unaffected by evaporative fractionation,if the difference between the boi

关 键 词：轻烃组分 蒸发分馏 成因类型 成熟度 四川盆地 

分 类 号：TE122.113[石油与天然气工程—油气勘探]