The Zhujiangkou basin is a special tectonic location of passive continental margin with complex regional background and oil and gas geological conditions. The region has not only basic characteristics of Cenozoic continental rift and fault basin in eastern China but also its unique features. Because oil and gas geological conditions are different in different basin zones, there exist the regularity of migration and accumulation of oil in the north and that of gas in the south, and the characteristics of association and superimposition of various resources are obvious: The north rift zone and the East Sha uplift shallow water zone constitute the thinning location of the continental crust, with the scale of the fault depression and sedimentation being smaller than that of the deep water area in the north rift zone; in addition, the area has low geothermal gradient and small heat flow, its thermal evolution of source rocks is in the range of oil window, and it produces large quantities of oil accompanied by a small amount of oil type gas, thus forming a petroleum accumulation zone in the sallow water of north continental shelf, which mainly includes Wenchang, Yunping, Xijiang, Huizhou, Lufeng and Liuhua oil fields. The exotic source mechanism of the oil and gas migration and accumulation system is the Oligocene delta sandstone and Miocene reef limestone in the area. There exist large quantities of natural gas and a small amount of light oil, which mainly include gas reservoirs of LW3-1, LH34-2 and LH29-1 and oil reservoir of LH16-2 in eastern Baiyun depression and a small gas reservoir group in Panyu uplift of Baiyun depression, which constitute a rich natural gas district with resource potential of oil and oil-gas in the south rift zone and the south uplift zone. Because the south rift zone and the deep water zone of southern uplift constitute the location of near -ocean crust characterized by thin crust and large -scale fault depression, the area has more marine hydrocarbon source rocks than northern shallow water. There exist high geothermal gradient and large heat flow ' in this area, and the thermal evolution of the source rocks is at the stage of mature-highly mature condensate oil and wet gas; besides, there is mixed source mechanism of hydrocarbon migration and accumulation characterized by the hydrocarbon system of Oligocene delta coastal sandstone and the deep -water fan system, and there also exists the paragenetic and superimposition relationship between gas hydrates in the seafloor and shallow gas and conventional oil and gas in the deep water.%珠江口盆地处在南海东北部准被动大陆边缘的特殊大地构造位置,其区域背景及油气地质条件复杂.该区不仅具有中国东部新生代陆相断陷盆地的基本特征,亦具本身的特殊性.由于盆地不同区带油气地质条件的差异,故具有明显的“北油南气”分布规律及纵向上多种资源叠置共生与复合的特点:北部裂陷带及东沙隆起浅水区,处于减薄的洋陆过渡型地壳靠近陆缘一侧,其古近系断陷规模及半地堑洼陷沉积充填规模均比相邻的南部裂陷带深水区小,且地温梯度低、大地热流小,烃源岩有机质热演化处在油窗范围,以产大量石油为主伴有少量油型气,构成了以文昌、恩平、西江、惠州及陆丰油田群和流花油田群为主的北部浅水油气富集区.该区具有上渐新统三角洲砂岩及中新统礁灰岩外源型油气运聚成藏机制及含油气系统；南部裂陷带及南部隆起周缘深水区,以邻近深水区的白云凹陷北坡—番禺低隆起中小气田群和白云凹陷东部深水区LW3 -1、LH34-2及LH29-1等天然气藏为代表,构成了以天然气为主但亦具石油及水合物资源潜力的深水油气富集区.由于南部裂陷带深水区处在洋陆过渡型地壳靠近洋壳一侧,地壳薄而裂陷深、断陷规模大,其与北部浅水区相比多了一套上渐新统海相烃源岩.该区地温梯度及大地热流偏高,烃源岩多处在成熟-高熟凝析油及湿气阶段,以产大量天然气及少量轻质油和凝析油为主,具有上渐新统陆架边缘三角洲砂岩和中新统深水扇混源型天然气运聚成藏机制及含油气系统.油气纵向分布具有深水海底天然气水合物及浅层气/生物气与深部常规油气共生叠置的关系.
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