西藏比如盆地下白垩统烃源岩特征  

Characteristics of the Lower Cretaceous source rock in Biru Basin,Tibet

作　　者：王先美[1] 郑和荣[1] 王毅[1] 祁开令[2] 伍新和[1] 

机构地区：[1]中国石化石油勘探开发研究院,北京100083 [2]中国石化南方勘探公司,四川成都610041

出　　处：《石油学报》2012年第5期822-829,共8页Acta Petrolei Sinica

基　　金：国家自然科学基金项目(No.41072160);中国石化海相前瞻性项目"青藏特提斯活动古地理与油气远景"(T060007ZS15)资助

摘　　要：比如盆地下白垩统多尼组以海陆过渡相沉积体系为主,发育典型三角洲相沉积构造。通过对残留盆地不同部位观测点数据统计、样品测试与分析,认为多尼组烃源岩累计厚度巨大,有机质类型以Ⅱ1型与Ⅲ型为主,有机质丰度较高,TOC主峰分布在0.40%～1.20%;有机质Ro主峰分布在2.00%～5.00%,处于高—过成熟演化阶段。对多尼组烃源岩热演化指标Ro偏高的原因进行探讨,初步认为特提斯构造域独特的构造演化背景下,中生界的褶皱、堆垛加厚,以及燕山期—喜马拉雅期岩浆、热液等方面作用引起的中生界区域变质作用与局部构造变质作用,是导致中生界有机质高演化及其出现演化程度地区性差异的重要因素。由此提出,青藏高原油气勘探与评价应注重喜马拉雅期构造演化对油气富集与保存的研究。The Lower Cretaceous Duoni Formation in Biru Basin is dominated by paralic deposits with sedimentary structures of well- developed typical delta facies. Statistical data from different observation points of the residual basin, sample analyses and measure- ments showed that source rocks of Duoni Formation have a great accumulated thickness, dominant type Ⅱ and type Ⅲ kerogens and a high abundance of organic carbon. The TOC ranges mostly from 0.40% to 1.20%, and Ro varies mainly between 2.0% and 5.0%, indicating a high to post maturity stage. Major factors that result in a higher maturity of Duoni Formation hydrocarbon source rock were preliminarily attributed to the Mesozoic regional metamorphism and local tectonic metamorphism caused by forma- tion thickening of the Mesozoic folding, superimposition, magma intrusion and hydrothermal fluid having developed from the late Yanshanian to Himalayan stages under unique evolutionary settings of the Tethys structural domain. As one of residual basins of Ti- bet, Biru Basin is of Mesozoic source rocks with higher Ro values and regional differences in thermal evolution, therefore, the tecton- ic evolutionary history of the Himalayan stage should be regarded as a key factor controlling oil ＆ gas accumulation and preservation conditions in Tibet Plateau.

关 键 词：比如盆地 中生界 有机质丰度 有机质成熟度 有机质类型 

分 类 号：TE122[石油与天然气工程—油气勘探]