厄瓜多尔Oriente盆地南部区块沉积特征

Sedimentary characteristics in the South Block of Oriente Basin,Ecuador

陈诗望 姜在兴 田继军 秦兰芝 徐小林

Chen Shiwang Jiang Zaixing Tian Jijun Qin Lanzhi Xu Xiaolin

中国地质大学能源学院, 北京 100083; 中国科学院广州地球化学所, 广东广州 510640; 中国石油勘探开发研究院廊坊分院, 河北廊坊 065007

China University of Geosciences, Beijing 100083; Guangzhou Geochemical Institute, CAS, Guangzhou, 510640; Langfang Branch of Research Institute of Petroleum Exploration & Development, PetroChina, Langfang 065007

通过构造演化和地层发育特征分析,将厄瓜多尔Oriente盆地南部区块Napo组划分为4个层序。根据岩心中的潮汐层理、羽状交错层理、冲洗交错层理、具有大量贝壳等特征,识别研究区具有潮坪沉积环境。针对其沉积坡度缓,碎屑岩和碳酸盐岩互层沉积的特点,建立了缓坡混积陆棚边缘的沉积相模式,认为Oriente盆地南部区块Napo组发育有海岸平原、潮坪、局限台地和混积陆棚相。相序的垂向组合和平面迁移受海平面升降的控制,指出潮坪砂岩主要出现在各层序的陆架边缘体系域,水下浅滩砂岩出现在海侵体系域。从沉积角度看,潮汐水道砂体是最好的储层砂体。

Through study on structural evolution and analysis of sequence growth characteristics,Napo for-mation in South Block of Oriente Basin,Ecuador was divided into 4 sequences.On the basis of tidal bed-ding,herringbone cross-bedding,flush cross bedding and plenty of shells,it has been identified that the sedimentary environment of the study area is of tidal flat environment.In view of gentle slopes and interbe-ded sedimentation of siliciclastic rocks and carbonates,the sedimentary facies model was built that is mixed sedimentation of siliciclastic and carbonate on the gentle slope shelf margin.It's believed that the sedimentary facies of coastal plain,tidal flat,restricted platform and continental shelf are developed in Napo Formation in the South Block.Vertical array and plane migration of phase sequences were controlled by sea level fluctuation.The author pointed out that tidal flat sandstone mainly existed in shelf margin system in every sequence,and subaqueous shoal sandstone existed in transgression system.Through the analysis of sedimen-tation,the sand body of tidal channel was considered as the favorite reservoir.