桑托斯盆地白垩系湖相碳酸盐岩微生物礁滩的成因

巴西桑托斯盆地为典型的南大西洋被动大陆边缘含盐盆地,裂谷期白垩系Barra Velha组发育湖相碳酸盐岩微生物礁滩,是盐下含油气系统主要储层,叠层石微生物灰岩是组成微生物礁滩的主要岩石成分。本文通过地震剖面的振幅反射结构、钻井岩性剖面、岩心观察、岩心薄片分析,研究微生物礁滩主要特征。叠层石颗粒组成岩石格架,粒间孔发育,是优质储层,主要分布在东部隆起带上。鲕粒灰岩颗粒为叠层石,颗粒形态多样、大小不一,为叠层石微生物礁破碎后就近堆积、经波浪改造后的产物。桑托斯盆地湖相碳酸盐岩微生物礁滩的形成主要受控于古环境、水体深度变化及藻类改造作用。

Genetic analysis of microbial reef-bank of Cretaceous lacustrine carbonate in Santos Basin,Brazil

Lacustrine environment is different from marine environment and the lacustrine carbonate rocks have its unique characteristics and genesis.In recent years a special reservoir of lacustrine carbonate is found in China and abroad.The study area of Santos Basin is a typical passive continental margin in the south Atlantic salt basins and lacustrine carbonate microbial reef-beach composed of stromatolites microbial limestone is the main reservoirs in the salt petroleum system.The main characteristics of microbial reef-beach is studied on the basis of comprehensive analysis of seismic reflection structure,properties of three-dimensional seismic sections,core deposit structure,drilling lithological profile,logging curve.The rock framework which is composed of stromatolites particles and the intergranular pores are main factors forming the high quality reservoir distributed mainly in the eastern uplift zone.The fragments of oolitic limestone are stromatolites with varied morphology and varied sizes.They are resulted from the nearby accumulation and wave reformation after the fragmentation of microbial reef-beach.It is considered that the formation of lacustrine carbonate microbial reefs in Santos Basin is controlled by ancient environment,changes of water depth and algae transformation.