阿联酋下白垩统舒艾巴组生物礁沉积模式

Sedimentary model for the organic reefs from the Lower Cretaceous Shuaiba Formation in the United Arab Emirates

关键词:  阿联酋  舒艾巴组  生物礁  厚壳蛤  沉积模式

Key words:  United Arab Emirates  Shuaiba Formation  organic reefs  rudist  sedimentary model

摘要:

本文在露头分析和钻井资料研究的基础上,结合区域地质背景,对阿联酋地区下白垩统舒艾巴组生物礁沉积特征进行了分析,确定了该区生物礁的沉积模式及有利储层发育相带。舒艾巴组沉积时期,具备优越的生物礁发育条件,造礁生物主要为厚壳蛤。研究区舒艾巴组碳酸盐台地具有"缓斜坡镶边台地"沉积特征,自盆地边缘向盆地内部,依次发育浅海低能碳酸盐陆架、浅海高能碳酸盐陆架、深水低能碳酸盐陆架、盆地斜坡相和深海盆地相。浅海高能碳酸盐陆架-盆地斜坡相带为生物礁发育带及油气富集区。其中浅海陆架边缘的高能相带为厚壳蛤生物礁发育的最有利区域,储层物性最好,厚壳蛤礁主要形成于早期存在的藻类粘结灰岩台地高点和台地边缘,礁核和礁前为优质储层发育带。研究该区生物礁的沉积模式与分布规律,对该区生物礁储层油气勘探具有重要的指导意义。

Abstract:

Sedimentary characteristics of the organic reefs from the Lower Cretaceous Shuaiba Formation in the United Arab Emirates are discussed on the basis of outcrop and drilling data in integration with regional geological background. During the deposition of the Lower Cretaceous Shuaiba Formation,abundant reef-building organisms such as rudists and algae were well developed in the United Arab Emirates. The carbonate platforms in the Shuaiba Formation appear as the "ramp-rimmed platforms",and basinwards display the arrangement of shallow-sea low-energy carbonate shelf,shallow-sea high-energy carbonate shelf,deep-water low-energy carbonate shelf,basin-slope facies and deep-sea basin facies. The shallow-sea high-energy carbonate shelf and basin-slope facies zones are believed to be the profic areas due to the development of organic reefs. The high-energy facies zone on the shallow-sea shelf margins is delineated as the favourable area for the development of the rudistid reefs. The sedimentary models for the development of organic reefs and division of sedimentary facies for the favourable reservoirs are constructed for the Shuaiba Formation,and will be of significance to the oil and gas exploration in the organic reef reservoirs in the study area.