摘要
准噶尔盆地从石炭一二叠纪的“热盆”（古地温梯度0．05-0．07℃／m）演变成新生代典型的“冷盆”（地温梯度0.02－0.023℃／m），使盆地两套主要烃源岩：二叠系和侏罗系烃源岩热演化程度（成熟度）具有明显的差异。二叠系径源岩成熟度普遍很高，大部分达到过成熟阶段；而侏罗系烃源岩成熟度则很低，即使埋深超过5000m，实测镜质组反射率R°％仅为0．5－0．6，相当于生油初期（低成熟）阶段。通过应用Waples模型和Sweeney－Burnham模型两种方法对盆地13口深井进行古地温梯度拟合计算表明：对于热演化过程主要发生在白垩纪之前，高地温梯度背景下的8口深井，烃源岩热演化受压力的影响小，成熟度相对较高；而对于热演化过程主要发生在白垩纪之后、低地温梯度背景下的5口井，烃源岩热演化受压力的影响较大，成熟度异常偏低，实测镜质组反射率低于用Waples模型和Sweeney－Burnham模型计算的镜质组反射率。
The Junggar basin evolved from a 'hot basin' in Carboniferous and Permian (thermal gradient(0.05-0.07℃/m) to a 'cold basin' in Cenozoic (thermal gradient:0.02-0.023℃/m). It made a striking difference of thermal maturities between the two main source rocks of this basin, i. e. Permian and Jurassic hydrocarbon source rocks. The thermal maturities of Permian source rocks are very high, mostly postmature, but those of Jurassic source rocks are much low, just at the eary stage of hydrocarbon generation (R° 0.5%-0.6%), even at depth over 5000m. Two thermal maturation models presented by Wapes and by Sweeney and Burnham have been used to determine the paleothermal gradients of 13 boreholes. The thermal maturation of the source rocks from 8 of 13 boreholes, which was under hot thermal regime before Cretaceous period and less influenced by pressure retardation, relatively rapidly proceeded. In contrast, to that of the soupee rocks from the other 5 boreholes, which was under cold thermal regime after Cretaleous Period and severely influenced by pressure retardation, proceeded very slowly. In the later case, the observed thermal maturity data are much lower than those calculated from those two thermal maturation models.
出处
《地球化学》
CAS
CSCD
北大核心
1997年第6期1-7,共7页
Geochimica
基金
国家自然科学基金!49302032
新疆石油管理局勘探开发研究院资助
关键词
盆地
地热历史
古地温
地下热流
paleothermal gradients, pressure retardation, Junggar Basin
