曾母盆地油气地质条件、分布特征及有利勘探方向

Hydrocarbon geology,distribution and favorable exploration direction in Zengmu basin,South China Sea

以前人大量研究成果为基础,综合利用钻井、地震等资料,对中国南海曾母盆地构造单元进行了重新划分。结合南海构造演化背景分析,认为曾母盆地新生代经历了渐新世—早中新世断拗期和中中新世—第四纪拗陷期2个构造演化阶段,发育了不同的物源体系和沉积相带,具有不同的沉积充填特征,断拗期形成煤系和陆源海相2类主力烃源岩,拗陷期形成中—上中新统生物礁主力储层与上新统—第四系区域泥岩盖层。曾母盆地油气分布在平面上呈南油北气的特征,垂向上主要分布于中—上中新统;发育生物礁和构造2种油气藏类型,具有下生上储型和自生自储型2种成藏模式。曾母盆地西北部的康西凹陷中北部,特别是深水区,是下步油气勘探的有利区。

Based on a lot of previous research results, drilling and seismic data were comprehensively used to redivide Zengmu basin into tectonic units in South China Sea. By an analysis in combination with tectonic evolution in South China Sea, it is considered that there are two tectonic evolution stages in Cenozoic Zeng- mu basin, i.e. Oligocene-Early Miocene faulted depression and Middle Miocene-Quaternary depression, with different provenance systems and sedimentary facies developed. Two types of major source rocks, i. e. the coal measures and terrigenous marine facies, formed in the faulted depression stage, and Mid-Upper Miocene reef （the main reservoir rock） and Pliocene-Quaternary regional mudstone deposited in the depres- sion stage. Hydrocarbon distribution in Zengmu basin may be areally characterized by south oil and north gas, and vertically concentrated in Mid-Upper Miocene. There are reef and structural hydrocarbon traps and two accumulation patterns, i.e. the lower-generation and upper-reservoiring and the self-generation and self-reservoiring. The central-north part of Kangxi sag in the northwestern Zengmu basin will be a fa- vorable direction for the future exploration, especially its deep water area.