羌塘盆地有机质热演化与成烃史研究

STUDY ON ORGANIC MATTER’S MATURATION AND HYDROCARBON-GENERATING HISTORY IN THE QIANGTANG BASIN

秦建中

Qin Jianzhong

中国石油化工股份有限公司 石油勘探开发研究院 无锡石油地质研究所, 江苏 无锡 214151

Wuxi Research Institute of Petroleum Geology, SINOPEC, Wuxi, Jiangsu 214151, China

对青藏高原羌塘盆地中生界7 000多块样品的分析数据进行筛选和综合研究可知,侏罗系烃源岩在羌塘盆地中部尚处于成熟生油阶段,向四周成熟度逐渐增高;上三叠统肖茶卡组烃源岩几乎全部处于高成熟—过成熟,成熟生油范围已经很小.羌塘盆地有机质成熟度主要受古地温、构造变形程度和火成岩及深成热流的控制.盆地中部及东部主要受最高古地温或最大古埋藏深度的影响;盆地断裂或褶皱带附近及其盆地边缘主要受强烈不均衡压力的影响;而在盆地西部,基底断裂带的深成地下热流可能是主要影响因素.盆地中部具有2次(或3次)主要生烃过程(侏罗纪晚期—白垩纪早期与第三系沉积时期),特别是新近纪中新世早期至中新世后期,侏罗系烃源层的生烃过程对油气藏勘探更为有利.

Researches on the analytical data more than seven thousands of Mesozoic samples from the Qiangtang Basin in Qinghai-Tibet Plateau show that the Jurassic source rock is still mature and generating oil in the center of Qiangtang Basin.The Jurassic source rock is more and more mature from the center to the margin of the basin.Almost all the T3x source rocks are high-mature to over-mature and the range of oil generation has already very small.The maturity of the organic matters in this basin is mainlly controlled by the palaeo-geotemperature,the degree of tectonic deformation and pyrogenetic rock and plutonic hot fluid.In the center and the east of the basin,the main influential factor of organic matter's maturation is the maximum palaeo-geotemperture or palaeoburial depth.Near the fault or folded zone in the basin and the margin of the basin,organic matter's maturation is mainlly affected by the strongly unbalanced pressure.And in the west of the basin,the plutonic hot fluid in the basement fracture zone may be the main influence factor of organic matter's maturation.There are two (or three) hydrocarbon-generating processes occurring in the Late Jurassic-Early Cretaceous and the time of Tertiary sedimenting.In particular,the hydrocarbon-generating process caused by the Jurassic source rock in the Early Miocene to the Late Miocene is more favorable to the petroleum exploration in this basin.

国家重点基础研究发展计划(973)项目(2005CB422102).

https://doi.org/10.11781/sysydz200604350