中国南方五省区陆相中小盆地石油地质特征分析

Petroleum geologic characteristics of medium-small continental basins in five provinces in South China

徐政语 姚根顺 张喜满 马庆林 黄羚 程刚 廖飞燕 王鹏万

Xu Zhengyu Yao Genshun Zhang Ximan Ma Qinglin Huang Ling Cheng Gang Liao Feiyan Wang Pengwan

中国石油勘探开发研究院杭州地质研究院, 杭州 310023 2. 南方石油勘探开发有限责任公司, 广州 510240

Hangzhou Research Institute of Petroleum Geology, Research Institute of Petroleum Exploration and Development, PetroChina, Hangzhou, Zhejiang 310023, China 2. South China Petroleum Exploration and Development Limited, Guangzhou, Guangdong 510240, China

中国南方5省区(琼、粤、滇、黔、桂)共发育晚白垩世-新生代陆相中小盆地63个,依据成盆背景可划分为6大盆地带、2种成盆环境,结合沉积充填过程归纳为4种沉积充填模式.东、中部盆地烃源岩发育时代早(以古近系为主)、厚度大(400～1000m、100～900m)、以湖相泥岩为主;西部复合与叠合盆地烃源岩发育时代晚(以新近系为主)、厚度偏薄(125～700 m)、以碳质泥岩及煤层为主;有机质丰度总体较高,但类型复杂,表现为"东好西差";烃源岩热演化程度总体呈现"东高西低"格局,东、中部盆地有机质处于未熟-低熟阶段,勘探应以未熟生物气-低熟油为主;西部处于未熟阶段,勘探应以未熟生物气为主.5省区盆地因沉积岩体系发育,砂岩储层物性总体较好,一般具有中-高孔、中-高渗的特征;同时,由于多数盆地在萎缩阶段充填有区域性展布的浅湖-湖沼相泥质岩,区域盖层相对发育,盆地储盖条件总体较好.据已有资料统计分析,5省区陆相中小盆地油气藏类型总体可归纳为构造、岩性、地层与复合4大类型.其中,东部盆地以构造类油气藏为主,西部盆地以岩性油气藏为主,中部盆地以复合型油气藏为主.

In 5 provinces (Hainan,Guangdong,Yunnan,Guizhou and Guangxi) in South China,about 63 medium-small continental basins generated from the Late Cretaceous to Cenozoic.6 basin zones and 2 basin generating environments were divided according to tectonic backgrounds.Combined with sedimentary and filling process,4 patterns were concluded.In the east and center of the study area,source rocks generated early (usually during Paleogene) and were featured by big thickness (400-1000,100-900m) and lacustrine mudstones.In the composite and superimposed basins in the west of the study area,source rocks generated late (mainly during Neogene) and were featured by smaller thickness (125-700m) and carbonate mudstones and coal beds.TOC values were high in these basins,but the organic types were complicated and decreased from east to west.The thermal evolution of source rocks also decreased from east to west.The eastern and central basins were during the immature and low-mature stages,and the exploration targets should be focused on immature biogas and low-mature oil.The western basins were during the immature stage,and immature biogas should be explored.As the result of abundant depositional system in these basins,physical property of sandstone reservoirs were fine,usually characterized by mid-high porosity and permeability.What's more,during the fading stage of basin,shallow lacustrine and swamp facies mudstones filled regionally and worked as seal.According to exploration data,petroleum pools in the study area were classified into 4 types including tectonic (mainly in the eastern basins),lithologic (mainly in the western basins),stratigraphic and composite (mainly in the central basins).

https://doi.org/10.11781/sysydz201202158