南海北部潮汕坳陷中生界烃源岩特征及分布预测  

Characteristics and distribution prediction of Mesozoic source rocks in Chaoshan depression, northern South China Sea

作　　者：何敏 朱晓军[3,4] 朱伟林 张青林[1,2] HE Min;ZHU Xiaojun;ZHU Weilin;ZHANG Qinglin(CNOOC Deepuuter Development Ltd.,Shenzhen,Guangdong 518054,China;CNOOC Chima Limited,Shenuzhen Branch,Shenzher,Guangdong 518054,China;State Key Laboratory of Marime Geology,Tongji Umiversity,Shanghai 200092,China;Research Center for Marine Resources,Tongji Unriversity,Shanghai 200092,China)

机构地区：[1]中海石油深海开发有限公司,广东深圳518054 [2]中海石油(中国)有限公司深圳分公司,广东深圳518054 [3]同济大学海洋地质国家重点实验室,上海200092 [4]同济大学海洋资源研究中心,上海200092

出　　处：《中国海上油气》2023年第1期40-49,共10页China Offshore Oil and Gas

基　　金：国家自然科学基金重点基金项目“南亚-东南亚特提斯演化的油气资源效应(编号:92055203)”;“十三五”国家重点研发计划子课题“南海多类型水合物藏富集规律及成藏模式(编号:2017YFC0307301-1)”;中海石油(中国)有限公司科研项目“南海北部中生界油气成藏主控因素及勘探方向研究(编号:YXKY-2018-SHENHAI-01)”部分研究成果。

摘　　要：潮汕坳陷是南海北部迄今钻遇中生界为数不多的区域,对其开展中生界烃源岩特征及分布预测,有助于南海北部中生代油气资源评价。本文通过分析潮汕坳陷及其围区华南陆缘、台西南盆地的中生界烃源岩特征,结合弧前盆地的热流分布,对潮汕坳陷中生界烃源岩及其分布特征作出评价。研究结果表明,南海北部潮汕坳陷中生界烃源岩TOC含量可达1%以上,坳陷围区烃源岩TOC含量可达2%以上,且随着时代变老,烃源岩TOC含量有增大的趋势。坳陷内中生界烃源岩有机质类型主要为Ⅱ—Ⅲ型,有机母质主要来自陆生高等植物的输入,水生低等生物贡献少。坳陷围区烃源岩处于成熟—过成熟阶段,基于弧前盆地的热流分布特征推测坳陷内部热流值低,坳陷内中生界具备发育有利烃源岩的成熟演化条件。整体上,潮汕坳陷中生界具备发育有利烃源岩的地质条件,主要发育于海陆过渡相、与三角洲前缘相关的浅海陆棚相以及半深海—深海相,相对优质的烃源岩发育于地层时代偏老的中生界地层,该区可作为南海北部油气资源勘探重要的战略接替领域。The Chaoshan depression is one of the rare regions that have drilled the Mesozoic strata in the northern South China Sea. To assess the Mesozoic petroleum resources in the northern South China Sea, it is significant to characterize the Mesozoic source rocks of the Chaoshan depression and predict its distribution. This study utilizes the Mesozoic source rocks collected from the Chaoshan depression and its adjacent regions(including the continental margin of South China, and Taixinan basin) to examine the characteristics and distribution of Mesozoic source rocks of the Chaoshan depression, with the aid of analyzing the heat-flow distribution of the fore-arc basin. The results show that total organic carbon(TOC) content can be more than 1% in the Mesozoic source rocks of the Chaoshan depression and up to over 2% in its adjacent regions, and the TOC is elevated with the stratigraphic age of source rocks. In the Chaoshan depression, the organic matter of the Mesozoic source rocks is mainly type Ⅱ—Ⅲ, which is dominantly contributed from the input of terrestrial plants with scarce aquatic organisms. The Mesozoic source rocks in its adjacent regions are in mature-over-mature stages. Considering the heat-flow distribution of the fore-arc basin, we speculate that the heat-flow values are low in the inner part of the Chaoshan depression, and the Mesozoic strata in the depression possess the maturation conditions for the development of favorable source rocks. Overall, the Mesozoic in the Chaoshan depression has geologic environments for the development of favorable source rocks, which are mainly developed in marine-continental transition facies, shallow marine continental-shelf facies related to prodelta, and semi abyssal-abyssal facies, and the source rocks with relatively high quality are developed in the Mesozoic strata with older stratigraphic age. Therefore, the Chaoshan depression can be regarded as an important strategic replacement region for oil and gas exploration in the northern South China Sea.

关 键 词：烃源岩 中生界 潮汕坳陷 南海北部 弧前盆地 

分 类 号：TE121.1[石油与天然气工程—油气勘探]