南沙东北部海域礼乐盆地含油气组合静态地质要素分析

Analysis of static geological elements of petroleum-bearing combinations in the Lile basin, northeastern Nansha

针对礼乐盆地含油气组合静态地质要素的分析表明,盆地内主要发育中生界、古新统—中始新统和下渐新统3套烃源岩,并以中、下两套源岩生烃潜力最好;砂岩、碳酸盐岩和生物礁是盆地的主要储层类型,砂岩储层在中、新生界内广泛发育,而碳酸盐岩和生物礁储层则主要发育于上渐新统—第四系;盆地总体上缺少广泛发育、封盖性能良好的区域性盖层,但局部性盖层发育,且封闭性能良好。盆地主要存在3套含油气组合:中生界含油气组合,这是盆地内较有远景的一套含油气组合;古近系含油气组合,这是盆地最主要的勘探目的层系;新近系含油气组合,该套组合在盆地中部隆起难以形成良好的油气组合关系,而在盆地坳陷区,尤其是南部坳陷则可形成良好的油气组合关系。

Analysis of static geological elements of petroleum combinations in the Lile basin indicates that there are three suites of source rock in the Lile basin, i.e. lower Oligocene, Paleocene to Miocene and Mesozoic, of which the second and third suites have better hydrocarbon-generating potential. Sandstone, carbonate rocks and organic reefs are the main reservoir types, of which the sandstone reservoir is widely developed in the Meso-Cenozoic strata, while the carbonate and organic reef reservoirs are mainly developed in the upper Oligocene to Quaternary. Generally, the basin is lacking in widespread regional cap rocks with good sealing properties, but locally the cap rocks are well developed and have good sealing properties.. There are three petroleum-bearing combinations in this basin, i.e. the Mesozoic, Paleogene and Neogene petroleum-bearing combinations. The Mesozoic one has good oil-gas prospects; the Paleogene one is the most important exploration target in the basin and has the best prospect; and for the Neogene one, it is possibly difficult to form a good petroleum combination in the uplift in the central part of the basin, whereas in the depressions of the basin, especially in the southern depression, a good petroleum combination may be formed.