珠江口盆地岩性油气藏类型及形成条件——以惠西南地区中新统珠江组为例

珠江口盆地惠西南地区新近系珠江组发育古珠江三角洲前缘的连续型尖灭砂体和受波浪或潮流等改造再沉积的独立型尖灭砂体。根据研究区珠江组岩性油气藏的勘探实践,综合砂体类型与构造背景,把珠江组岩性油气藏分为3类:上倾尖灭型岩性油气藏,主要发育在东沙隆起区侧翼的鼻状构造带;背斜-上倾尖灭复合型岩性油气藏,主要发育在凹陷内部的古潜山构造带;断层-上倾尖灭复合型岩性油气藏,主要发育在断层下降盘的逆牵引构造带以及由倾向相反的正断层所夹持的凸起带。珠江组岩性油气藏为下生上储型,古近系文昌组提供了充足的油源,有利的构造背景和由断层、不整合面、渗透性砂岩及构造脊联合形成的油气垂向、横向运移路径是岩性油气藏成藏的重要条件。

Types and Forming Conditions of Lithologic Oil and Gas Reservoirs in Zhujiangkou Basin:A Case in Miocene Zhujiang Formation,Southwestern Huizhou Sag,Zhujiangkou Basin

The ancient Zhujiang delta developed in Neogene Zhujiang Formation, Zhujiangkou Basin. In the southwestern Huizhou Sag and in the western Dongsha Uplift, the continuous sand bodies and the independent sand bodies developed on the delta front, and the latter is modified by waves or tidal currents. Considering the sand body type and tectonic setting, the lithologic reservoirs in Zhujiang Formation can be divided into three categories:monocline-uplifting type, mainly developed in a nasal tectonic zone on the flanks of Dongsha Uplift; anticline-uplifting type, mainly developed in the buried hill; and fault-uplifting type, mainly developed in the hanging wall of rol-over anticline or in the horst. The reservoir in Zhujiang Formation has a lower-generation and upper-storage pat ern. Paleogene Wenchang Formation is a sufficient source-rock layer. The favorable tectonic setting and the transport system which is composed of fault, unconformity, permeable sandstone and structural ridge are the important conditions for the lithologic reservoirs in Zhujiangkou Basin.