西非北加蓬次盆G区块UPC段油气成藏模式及主控因素

Reservior Formation Model and Main Controlling Factors of G Block in North Gabon Sub-basin

加蓬盆地作为西非被动大陆边缘重要的含油气沉积盆地,是目前油气勘探的热点地区,而G区块是中国在北加蓬次盆地的重要投资勘探开发区块。对该区块地层和沉积特征,以及烃源岩、储层、盖层、输导体系等油气成藏条件的分析表明,G区块石油地质条件优越,发育有优质烃源岩,而UPC段作为G区块的主力产油层,储层物性很好,且该区块储盖组合配置关系良好。G区块油藏多为受构造控制的断背斜、断块油藏,油气主要富集在构造高点。研究表明,G区块油气成藏模式为"深源充注,断层盐边砂体输导,构造成藏",油气成藏的主控因素为与盐运动相关的构造圈闭。

The Gabon basin is a sedimentary basin with oil and gas in the passive continental margin of West Africa, and is considered as a main hydrocarbon exploration area. The G block is a key investment block in north Gabon sub-basin. The petroleum geological conditions of the G block are favorable. As a typical oil and gas reservoir in the passive continental margin basin, the oilfield in the G block could be a good reference for other blocks in terms of the geological condition and the hydrocarbon accumulation and distribution. In order to reveal the hydrocarbon accumulation and its main control factors for the oilfields in the G block, this paper analyzes the source rock, the reservoir, the cap rock, the trap and the hydrocarbon migration system in terms of stratigraphic and structural characteristics. It is confirmed that in the G block there are high quality resource rocks, sand reservoirs of good petrophysical properties, and the reservoir and seal assemblage is good. The UPC member is the main pay zone in the G block. The oil reservoirs in the G block are mainly structural traps such as the anticline and fault blocks controlled by tectonic activities, and the hydrocarbon accumulates mainly in the high structural closer. This paper presents the accumulation model in the G block, including the generation and feed from the deeper source rock, the migration through faults, salt and sandstone, the oil and gas accumulation in structural traps, and the main factors for the hydrocarbon accumulation are traps related with salt structure.