塔里木盆地志留系沉积构造及沥青砂岩的特征

研究了塔里木盆地志留系的沉积特征、构造特征与演化,以及沥青砂岩在志留系的分布规律。塔中地区志留系在纵向上分为三个储盖组合。塔中、塔北及柯坪三大古隆起控制着沥青砂岩的分布。在塔中地区志留系沥青砂岩主要分布在五个次级构造带上,塔北地区的均分布在晚加里东期的区域隆起部位。研究还表明,塔里木盆地志留系沥青砂岩的分布均受控于泥岩盖层和物性,两种情况都说明这些沥青砂岩主要为古油气藏破坏的产物。志留系砂岩中沥青分布在微观上有两种赋存状态:一种是块状,另一种是浸染状。在偏光镜下,可分为油质沥青(晚期)和胶质—沥青质沥青(早期)两种,两者常常共存,含量为互补关系。

THE DEPOSITIONAL AND STRUCTURAL SETTINGS AND THE BITUMINOUS SANDSTONE DISTRIBU-TION CHARACTERS OF THE SILURIAN IN TARIM BASIN

The depositional and structural characters and the tectonic evolution,as well as the distributional patterns of bituminous sandstone of the Silurian in Tarim B asin were studied in detail in this paper.In Tazhong area,vertically,the Siluria n can be divided into three sets of reservoir/cap rocks combination.The three pa leo-uplifts of Tazhong,Tabei and Keping controlled the bituminous sandstone dis tribution in the basin.In Tazhong area,the Silurian bituminous sandstone are mai nly distributed in five sub-structural zones,and in Tabei area,all distributed in regional uplifts of late Caledonian.The study also shows that the distributio n of the Silurian bituminous sandstone in Tarim is controlled by the distributio n and physical property of muddy cap rocks,and these indicate that the bituminou s sandstone are mainly the products of the destroyed palaeo-oil pools.Microscop ically,there are two types of occurrence for the bitumen in the Silurian sandsto nes:one is massive,and another is disseminating.Under polarizer,two kinds of bit umen,oily(late hydrocarbon filling) and colloidal/asphaltic (early filling),resp ectively,can be observed,and both of them often co-exist and their amounts are complementary.