琼海凸起新近系低幅-低阻油藏形成条件及成藏模式

综合应用油气地球化学、储层沉积学及成藏综合研究方法，剖析了琼海凸起文昌13区珠江组一段低幅-低阻油藏的油气来源、运移及成藏特征，深化了该区高阻、低阻油层成藏过程及运聚规律的认识。研究表明：1）文昌13-X珠江组一段低阻油层的原油主要来自文昌A凹陷恩平组浅湖相泥岩，该套烃源岩是文昌凹陷除文昌组中深湖泥岩之外的又一套优质生油岩。2）文昌13区珠江组一段低阻油层具备发育在低幅度披覆背斜上的构造＋岩性成藏模式，储层类型为浅海低能环境下发育的滨外砂坝泥质粉砂岩，储层岩性细、泥质含量高是低阻油层形成的主要原因。3）本区低阻油藏具备圈闭低幅度、储层低渗的特征，油气运移进入圈闭需要克服较大的毛细管阻力。4）本区珠江组一段低阻油层是其下覆高阻油层的次生油藏，形成纵向上高阻、低阻油层叠置伴生的油气富集带；低幅-低阻油藏勘探开发潜力大，是成熟区挖潜的重要领域。

Forming conditions and hydrocarbon accumulation patterns of the Neogene low resistivity reservoirs in low-amplitude structure of Qionghai Salient

Using geochemical,sedimentary and hydrocarbon accumulation analysis methods,this paper studied the characteristics of source rocks,hydrocarbon migration and accumulation of the low resistivity reservoirs of the 1^st Member of Zhujiang Formation(Zhu1)in the low-amplitude structure of Qionghai salient in Wenchang-13 block,Qionghai salient.The following results were obtained.The oil of the Zhu1 low resistivity reservoir in Wenchang 13-X is mainly sourced from the shallow lacustrine mudstone of Enping Formation in Wenchang sag,which is another high quality source rock in addition to the Wenchang Formation mudstone of mid-deep lacustrine faciesin.The low resistivity reservoirs of Zhu1 in Wenchang13 block are of structural-lithologic composite type developed in the low amplitude drape anticlines.The main reservoir consists of offshore fine muddy siltstone with fine grain and high mud content,which are the main causes of the low resistivity.The low resistivity reservoirs area characterized by low amplitude structure and low permeability.The low resistivity reservoirs are secondary accumulation with hydrocarbons sourced from the underlying high resistivity reservoir.The low resistivity and high resistivity reservoirs superimpose vertically to form a hydrocarbon enrichment zone.The low resistivity reservoirs in low amplitude structure are important targets for potential-tapping in mature area.