珠江口盆地文昌B凹陷及周边油气成藏特征与有利勘探领域

利用烃源岩分析、油—源对比和成藏综合分析等技术,研究了文昌B凹陷及周边的油气来源和成藏历程,阐明了不同区带的主力烃源岩与油气成藏特征,深化了油气成藏主控因素认识,提出了有利油气勘探方向。研究认为,文昌B凹陷文昌组浅湖相烃源岩是凸起区成藏的主要贡献者,是该区除众所周知的中深湖相优质烃源岩外的另一种优质烃源岩。南断裂带下降盘文昌组湖相烃源岩沉积期末经历了构造反转抬升,具有"延迟生排油、多期持续油充注"的成藏过程,三号断裂带下降盘具有"早期生排油、多期油气充注"的成藏过程。良好的文昌组湖相烃源岩、多幕式断裂活动、多套区域性优质储盖组合是该区复式油气成藏的主控因素。提出文昌B凹陷反转陡坡带、北斜坡中深层古近系、琼海凸起珠江组一段上部是有利油气勘探方向。

Petroleum accumulation characteristics and favorable exploration directions in Wenchang B Sag and its surrounding areas, Pearl River Mouth Basin

Based on source rock analysis,oil—source correlation and accumulation comprehensive analysis,oil source and accumulation process in the Wenchang B Sag and its surrounding areas were studied.Main source rock and hydrocarbon accumulation features in different regions were illustrated.Main controlling factors of hydrocarbon accumulation and favorable exploration directions were pointed out.Sha-llow lacustrine source rock of the Wenchang Formation in the Wenchang B Sag was the main contributor for accumulation in uplifting region besides the well-known middle—deep lacustrine source rock.At the end of deposition,lacustrine source rock of the Wenchang Formation in the downthrow of southern fault experienced tectonic inversion,resulting in the delay of oil generation and expulsion as well as the multi-stages of oil charging.The downthrow of fault No.3 was also characterized by early oil generation and expulsion as well as multi-stages of oil charging.Favorable lacustrine source rock of the Wenchang Formation,multi-stages of fault activities and sets of reservoir—caprock assemblages worked as the main controlling factors for hydrocarbon accumulation.Favorable exploration directions were pointed out,including the inverse abrupt slope and the middle—deep buried Paleogene of the northern slope in the Wenchang B Sag as well as the first member of Zhujiang Formation in the Qionghai uplift.