珠江口盆地珠三坳陷断层特征及其对油气成藏的控制作用

珠江口盆地珠三坳陷是一个断裂系统十分发育的箕状断陷盆地,其形成和演化受断裂强烈控制。在坳陷内主干断裂的控制下,坳陷分割为文昌A凹等9个构造单元,其中,文昌A,B,C凹陷为生油凹陷。断裂以北东东向为主,按照主干断裂和次级断裂的组合形态,平面上可划分出平行、雁列、帚状、"入"字型等4种组合样式;剖面上可划分为同斜"Y"型、反斜"Y"型、复合"Y"型、同向断阶等4种组合样式。断裂对油气成藏的控制作用主要包括对烃源岩分布、储集体发育和展布、油气生成和运聚的控制。该作用表现为有利和不利2个方面,通过分析,确定将主干断裂,特别是"Y"型断层发育地区作为珠三坳陷下一步油气勘探的重点区,而距离生油中心较远、受断层阻断运移通道的边缘隆起带应作为远景目标给予进一步研究。 

FAULT CHARACTERISTICS AND CONTROL ON PETROLEUM ACCUMULATION IN THE ZHU Ⅲ DEPRESSION,THE PEARL RIVER MOUTH BASIN

The Zhu Ⅲ Depression in the Pearl River Mouth Basin is a halfgraben-like depression with well-developed fault system.Formation and evolution of the depression have been controlled by faults.Controlled by main faults,the depression can be divided into 9 tectonic units such as the Wenchang A Sag,among which the Wenchang A,B and C Sags are petroleum generative.Faults in the depression are mainly NEE oriented.According to combination of the main and the secondary faults,there are 4 combination styles in plane,including parallel,en echelon,broom-like and ‘Y'-like.In section,there are also 4 combination styles,including homoclinal ‘Y'-like,reverse ‘Y'-like,complex ‘Y'-like and accor-dant fault step.Faults control source rock distribution,reservoir generation and distribution as well as petroleum generation and migration.The controlling effects may be favorable or unfavorable.The main faults,especially the ‘Y'-like faults generative region,are the key targets for petroleum exploration in the Zhu Ⅲ Depression.Uplifts along the edge of the depression which are far away from oil generation center and blocked by faults should be taken as long-term targets.