烃源岩TOC值变化与其生排烃效率关系的探讨  

An Approach to the Evolution of TOC Value for Source Rock and Its Relation to Efficiencies of Hydrocarbon Generation and Expulsion

作　　者：钟宁宁[1] 卢双舫[2] 黄志龙[1] 张有生[1] 薛海涛[2] 

机构地区：[1]石油大学(北京)教育部石油天然气成藏机理重点实验室,北京昌平102249 [2]大庆石油学院勘探系,黑龙江大庆163000

出　　处：《沉积学报》2004年第B06期73-78,共6页Acta Sedimentologica Sinica

基　　金：国家重点基础研究发展规划项目G19990433-07资助

摘　　要：采用实验模拟和数值模拟相结合的方法揭示了烃源岩有机碳(TOC%)的损失率DTOC一(TOC°-TOC)/TOC°的变化规律。当烃源岩生排烃效率很低时,DTOC都为负值,即在成熟演化过程TOC是增加的。随着生排烃效率提高,有机碳变化率DTOC逐渐增加(TOC损失率增大),烃源岩逐步由“增碳”进程转变为“减碳”进程。但只有生烃潜力很高的Ⅰ型有机质岩石,在生烃降解率和排烃效率极高的“理想”条件下,DTOC的增加(减碳进程)幅度才十分显著。指出基于有机质原始丰度恢复的碳酸盐岩烃源岩评价标准,可能过分强调了“减碳”的进程,很多情形下会美化原本比较差的烃源岩。Pyrolysis and numeric modeling techniques were adopted to reveal the loss rate of total organic carbon content (TOO with source rock maturation process. The TOC loss rate was presented as DTOC = (TOC°-TOC/TOC°. While source rock is of lower efficiencies of hydrocarbon generation and exclusion, the DTOC is a negative value, i. e. in this case the TOC value mount up with maturation progress. With increase in efficiencies of hydrocarbon generation and exclusion, DTOC goes up gradually, i. e. TOC loss rate increases and source rock therefore change its TOC evolution path from a 'carbon adding' process to a 'carbon reduction' process. There is only the type I kerogen source rock that under the ideal condition of extremely high efficiencies of hydrocarbon generation and exclusion the range of DTOC increase ('carbon adding' process) could be significant. It is evident that the criteria of carbonate source rock which bases on the recovery of original TOC value is likely an overestimate of 'carbon reduction' process. Thus, in many cases, it would sugar up originally poor source rock.

关 键 词：烃源岩 TOC值 有机质丰度 生排烃效率 数值模拟 

分 类 号：P593[天文地球—地球化学]