江汉盆地潜江凹陷潜三段盐间烃类特征及其指示意义

Hydrocarbon Characteristics of Inter-salt System in Qian 3 Member of Qianjiang Sag,Jianghan Basin and Their Indication

利用岩石热解与色谱-质谱分析方法对江汉盆地潜江凹陷潜三段页岩层系进行分子地球化学特征研究后发现,潜三段下部10韵律与11韵律层系在热解参数和分子地球化学方面具有明显差异。其中,10韵律层系岩石热解具有游离烃(S1)高、有机碳(TOC)含量高,而热解烃峰值温度(T_(max))低的特征,生物标志物参数表现出C_(29)甾烷异构化参数(S/(S+R)、ββ(αα+ββ))高,C_(35)升藿烷优势,反映成熟烃源岩的特征; 11韵律层系具有S1低、TOC含量低,而T_(max)高的特征,生标参数表现出C_(29)甾烷S/(S+R)低,呈未熟烃源岩的特征。综合考虑到地质因素的作用,认为潜三段10韵律存在侧向运移的烃类浸染,而其下部的11韵律则反映了源岩自身的地化特征。

The molecular geochemical characteristics of the shale system of the third member of Qianjiang Formation( Eq3) in Qianjiang Sag,Jianghan Basin,China were studied by rock pyrolysis and gas chromatography-mass spectrometry. The results show that there is difference in rock pyrolysis parameters and molecular geochemistry between 10 th rhythm layer and 11 th rhythm layer of the lower part of Eq3. The rock of the 10 th rhythm layer has the characteristics of high S1,high TOC,low Tmax,high S/( S + R) of C29 sterane and high C35 H,which shows the maturity character of organisms. While the rock of the 11 th rhythm layer has the characteristics of low S1,low TOC,high Tmax,and low S/( S + R) of C29 sterane,which shows the immaturity character of organisms. Considering geological factors,it is held that the 10 th rhythm layer was contaminated by hydrocarbons migrating laterally,while the 11 th rhythm layer reflects the geochemical characteristics of the source rock itself.