南海东北部潮汕坳陷及陆上邻区中生界烃源岩初步研究

Preliminary Studies on the Mesozoic Source Rocks in Chaoshan Depression,Northeastern South China Sea

潮汕坳陷属南海东北部陆坡区的一个中生代大型残留盆地,油气勘探及研究程度甚低。根据近年来潮汕坳陷及陆上邻区粤东、粤中的油气地质调查和LF35-1-1井钻探成果,系统分析了中生界烃源岩地质地球化学特征。初步研究表明,潮汕坳陷中生界侏罗系海相暗色泥岩为该区主要烃源岩,其母质类型以Ⅲ型干酪根为主,成熟度偏高,分布范围较广且稳定,具有较好的生烃潜力,属差—好烃源岩;白垩系暗色泥岩为次要烃源岩,母质类型亦以Ⅲ型干酪根为主,成熟度亦偏高。据层序地层分析,下白垩统下部地层具有一定生烃潜力,属差—中等烃源岩。海陆中生代地层对比表明,潮汕坳陷生烃条件比陆上邻区粤东、粤中好,海域大范围发育和保存的与陆上下侏罗统桥源组等烃源岩相当的沉积岩系,其有机质生成和保存条件较好,具较大生烃潜力。

The Chaoshan depression is a large Mesozoic residual basin in the continent of the northeastern South China Sea. On the basis of the geological survey and the data of the LF35- 1 -1 well in the Chaoshan depression and the Guangdong continental area, we analyzed the geological and geochemical characteristics of the Mesozoic source rocks. The results show that the main source rocks in the Chaoshan depression are Jurassic dark mudstones whose matrix is mature kerogen of type Ⅲ, and are widespread and stable with better hydrocarbon potential. The less important source rocks are Cretaceous mudstones, and the lower layers of the Lower Cretaceous also have some hydrocarbon potential according to sequence analysis. The Chaoshan depression has sedimentary rocks equivalent to the Jurassic Qiaoyuan and has good conditions for hydrocarbon generation.