塔里木盆地北部古近系-白垩系成岩相及其储集性能

塔里木盆地北部地区白垩系-古近系储集层岩性主要为处于中成岩阶段的岩屑砂岩和长石岩屑砂岩。在不同地区和不同层段, 岩石组成、成岩矿物组合、成岩演化、孔隙组合类型有明显的差异; 根据储集层中自生矿物种类、分布、生成顺序、孔隙类型组合和孔隙形成特征以及构造作用等对储集性能的影响, 将古近系-白垩系储集层成岩相划分为强胶结挤压致密型成岩相、中等胶结溶解型成岩相和弱胶结成岩相, 其中以方沸石和白云石组合胶结为主的储集层物性最好。根据不同地区、不同构造带古近系、白垩系储集层岩性、物性参数等将本区储集层分为4 个级别: Ⅰ、Ⅱ类储集层可以作为油气勘探的主要目的层, Ⅲ类储集层属低渗透储集层可以作为寻找天然气的目的层, 而Ⅳ类储 集层为特低孔特低渗非常致密型储集层, 甚至为非储集层。

Diagenetic Facies and Reservoir Quality of Paleogene-Cretaceous in Northern Tarim Basin

The Paleogene-Cretaceous reservoirs with lithic sandstone and greywacke lithic sandstone in northern Tarim basin is mainly in stage of medium diagenesis, and have obvious differentces among them in different areas, different intervals, rock composition, diagenetic evolution, diagentic mineral assemblage and pore type. This paper presents the diagenesis classification in terms of authigenic mineral type, distribution and genetic order as well as the effect of pore type assemblage, pore characteristic and tectonic action on the reservoirs, including the intense cementation and compaction diagenetic facies, the medium cementation and dissolution diagenetic facies and weak cementation diagenetic facies, among which the reservoirs with analcite-dolomite cementation are the best ones. Also, the reservoir quality is divided into four types of reservoirs base on the lithologic and pethophysical parameters of Paleogene and Cretaceous in different areas and different structural belts. TypeⅠ and Type II reservoirs could be as the main targets for oil and gas exploration, Type III low permeability reservoir is as the target for gas exploration, and Type IV reservoir with super low porosity-permeability and compaction even belongs to non-reservoir.