珠江口盆地白云凹陷烃源岩及北部油气成因

目前在珠江口盆地白云凹陷发现的最为重要的烃源岩分布于始新统和渐新统.其中始新统主要为Ⅰ-Ⅱ₁型文昌组湖相烃源岩,渐新统则以Ⅱ-Ⅲ型生气为主的恩平组泥岩为主,含煤及碳质泥岩夹层.油气源对比表明,白云凹陷北坡主要聚集了白云主洼恩平组Ⅱ₂型烃源岩在Ro值为1.2%~1.8%时生成的天然气.白云凹陷文昌组烃源岩厚度大,有机质丰度高,类型好,以早期生油为主,现今成熟生烃范围主要集中在凹陷的南部,是下一步勘探的重点方向.

Source rocks and origin of oil and gas in the northern Baiyun Depression of Pearl River Mouth Basin

The most important source rocks in Baiyun Depression of Pearl River Mouth Basin are the type Ⅰ─Ⅱ₁ lacustrine sediment of Eocene Wenchang Formation， and the type Ⅲ terrestrial shale and coalbearing strata of Oilgocene Enping Formation. The oilgas source correlation suggested that oil and gas in the north slope of Baiyun Depression was derived from the Oilgocene type Ⅱ₂terrestrial sediment. The pool filling process showed that natural gas was accumulated from Oilgocene source rocks in the stage of high vitrinite reflectance value from 1.2% to 1.8%. The abundance of source rocks in Wengchang Formation was evaluated as the best. The features of oilgas generation and accumulation of Wenchang Formation in early period were obvious. The mature source rocks are in the south areas of Baiyun Depression, which is the best region for oil exploration, and the northern slope of Baiyun Depression is the best region for gas exploration.