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东沙断隆位于香港东南约250km处的南海北部陆架～陆坡区的东沙台阶上,台阶水深介于100～400m之间。它是大型NE向中、新生代断隆带的一个组成部分,该断隆带把珠江口盆地分隔成南北两个地堑区。东沙断隆的基底由燕山陆绿活化带和燕山褶皱带组成。珠江口地堑的盖层由第三系和第四系组成,以第三系为主,厚达7000～10000m。但东沙断隆区在古新世至始新世期间大幅度隆升,下构造层(下第三系)仅在断隆区的小凹陷中存在。东沙断隆的形成和演化可划分为五个阶段:①基底形成阶段(J_2～K_1);②缓慢隆升阶段(K_2～E_2~2);⑦风化剥蚀阶段(E_2~3～E_3~1);④整体沉降阶段(E_3~2～N_1~2);⑤后期隆升阶段(N_1~3～Q)。东沙断隆的形成和演化对油气藏的形成起着明显的控制作用。在断隆区有较好的储集层和盖层,运移通道发育,而且,断隆长期处于较高部位,是周围断拗油气运移的主要目的地,上述所有因素,为在东沙新陛区形成大型油气藏创造了有利的条件。
The Dongsha Discontinuity is located on the Dongsha step of the northern South China Sea Shelf-slope region about 250km southeast of Hong Kong with a water depth of between 100 and 400m. It is a component of a large NE-trending Mesozoic and Cenozoic uplift belt that divides the Pearl River Mouth Basin into two northern and southern graben areas. The basement of the East Sha segment is composed of Yanshan land-green belt and Yanshan fold belt. The caprock of the Pearl River Mouth Graben is composed of Tertiary and Quaternary systems, mainly Tertiary, with a thickness of 7000-10000m. However, the Dongsha uplift zone was greatly uplifted during the Pliocene to the beginning of the Eocene, and the lower tectonic (lower Tertiary) only existed in the small sag in the uplift zone. The formation and evolution of the Dongsha fault can be divided into five stages: (1) the basement formation phase (J_2 ~ K_1); ② the slowly uplifting phase (K_2 ~ E_2 ~ 2); ② the weathering and erasing stage (E_2 ~ 3 ~ E_3 ~ 1) ; ④ overall sedimentation stage (E_3 ~ 2 ~ N_1 ~ 2); ⑤ late uplift stage (N_1 ~ 3 ~ Q). The formation and evolution of the Dongsha dyke uplift play a significant role in controlling the formation of oil and gas reservoirs. There are better reservoirs and caprocks in the uplifted area, and the migration channels develop. Moreover, the long-term breakage is at a higher level and is the main destination for the offshore oil and gas migration. All of the above factors are in the new The formation of large-scale oil and gas reservoirs in Maizhou district has created favorable conditions.