济阳坳陷民丰地区天然气成因

Origin of natural gas in Mingfeng area,the Jiyang Depression

胡晓庆 金强 王秀红 林腊梅 王力 王娟 王婷婷

Hu Xiaoqing Jin Qiang Wang Xiuhong Lin Lamei Wang Li Wang Juan Wang Tingting

济阳坳陷民丰地区天然气存在源岩热解和原油裂解成因的争议,利用古近系沙四段烃源岩、原油样品的热模拟实验与地质分析相结合的方法,提出了源岩热解气和原油裂解气的鉴别标志。源岩热解气以甲烷的快速生成为特征,成熟阶段,源岩热解气的环烷烃和苯含量低,高成熟阶段,源岩热解气和原油裂解气均以环烷烃和苯含量高为特征。民丰沙四段凝析油和天然气的ln(C/C)比ln(C/C)变化大,且环烷烃、异构烷烃和芳烃含量较高,具有高成熟阶段源岩热解气的特征,研究认为民丰地区天然气为源岩热解成因。

It is controversial about the origin of the natural gas in Minfeng area.A set of indexes for differentiating kerogen-pyrolysis gas and oil-cracked gas is presented based on geologic analysis and thermal simulation experiments on source rocks and crude oil samples from the Es.In mature phase,the kerogen-pyrolysis gas features in rapid generation of methane and low contents of cyclane and benzene.While in high mature phase,both kerogen-pyrogenic gas and oil-cracked gas are characterized by high contents of cyclane and benzene.The condensate oil and natural gas in Mingfeng area show a larger scope of ln(C/C) ranging from 2 to 6 than that of ln(C/C) varing from 1 to 1.5 and have relatively high contents of cyclane,isoalkane and aromatic hydrocarbon,revealing the characteristics of kerogen-pyrolysis gas in high mature phase.Therefore,it is believed that the natural gas in Minfeng area is of kerogen-pyrolysis gas.

10.11743/ogg20090112