【摘要】 从有机地球化学方面深入研究了银根—额济纳旗盆地查干凹陷的基本石油地质条件。查干凹陷下白垩统沉积时为一箕状断陷 ,沉积地层和烃源岩厚度变化大 ,主要烃源岩发育于下白垩统巴音戈壁组和苏红图组下段 ,厚约 0～ 2 40 0m。目前烃源岩有机碳含量为 0 .15 %～ 2 .66% ,热解生油潜量为 0 .0 7～ 10 .74mg/g,氯仿沥青“A”含量多数在 0 .0 2 2‰～ 3 .75 7‰ ,总烃含量为0 .0 49‰～ 2 .5 2 7‰。有机质丰度变化大 ,但可溶有机质含量相对较高。有机质主要由无定型草本植物降解和藻类组成 (占60 %～ 80 % ) ,其中II1型有机质占 5 0 %以上 ,推测原始有机质类型较好。该凹陷地热梯度较高 ,目前烃源岩镜质组反射率在0 .8%～ 2 .0 % ,处于成熟生油—湿气阶段 ,饱和烃色谱和色质参数也表明烃源岩已成熟。TTI计算表明其主要烃源岩主要生油期为晚白垩世。综合分析认为下白垩统烃源岩属较好烃源岩 ,具有一定的生油气潜力。图 5表 3参 5更多还原

【Abstract】 The principal condition s of petroleum geology in Chagan sag of Yingen Ejinaqi basin, Northwest China, have been studied from organic geochemistry angle in this paper. Chagan sag is h alf garben like so that the thickness of Cretaceous source rocks, of which the primary source rocks are Bayingebi Formation and Lower Suhongtu Formation of Low er Cretaceous, greatly differs from 0 to 2400 m in the different parts of this s ag. The TOC (Total organic carbon) value, the pyrolysis hydrocarbon potential, t he content of chloroform extract and the total HC content range from 0.15% to 2. 66%, 0.07mg/g to 10.74mg/g, 0.022‰ to 3.757‰ and 0.049‰ to 2.527 ‰, re spectively. Organic matter in abundance varies greatly, but the content of the s oluble is relatively high. Organic matter, in which type Ⅱ 1 of organic matter accounts for more than 50%, suggesting that it is better for hydrocarbon genera ting, is mainly composed of amorphous matter, degraded from herbal plants and al gae, accounting for 60 % to 80 % in organic matter. The geothermal gradient in C hagan sag is relatively high, and the reflectance of vitrinite ( R o) varies from 0.8% to 2.0%, showing that the organic matter should be at the stage of oi l generation to wet gas. Also, the parameters on GC and GCMS of saturated hydroc arbon indicate that source rocks have been maturated. The value of TTI shows that hydrocarbon is largely generated at late Cretaceous for the primary source rocks in Chagan sag. From the integrated analyses mentioned above, it is consid ered that Lower Cretaceous source rocks are favorable for petroleum generation a nd have a certain hydrocarbon potential.更多还原