束鹿凹陷沙河街组三段下亚段泥灰岩-砾岩致密储层储集空间类型及成因

通过偏光显微镜、荧光显微镜、阴极发光显微镜、场发射电镜和物性实验等手段,系统剖析了束鹿凹陷沙河街组三段下亚段泥灰岩-砾岩储层储集空间类型,探讨了储集空间成因及控制因素。研究区泥灰岩-砾岩主要发育纹层状泥灰岩、块状泥灰岩、颗粒支撑陆源砾岩、杂基支撑陆源砾岩、混源砾岩5种岩性,储层致密,孔渗极差,属特低孔特低渗储层。储集空间主要为次生孔隙和裂缝,发育溶孔、有机质孔、砾内孔、粒(晶)内孔隙、粒(晶)间孔隙等,以及构造缝、层间页理缝、贴砾缝、收缩缝、有机酸溶蚀缝等;其中,泥灰岩储集空间以有机质孔隙、页理缝、粒(晶)间孔隙为主,砾岩储集空间以砾内孔、溶孔、构造缝为主。储集空间的发育主要受构造作用、沉积作用、物源和成岩作用等因素综合影响。

Reservoir space types and its genesis in tight calcilutite-rudstone reservoir of the lower part of Member 3 of Shahejie Formation,Shulu sag

Using polarization microscope, fluorescence microscope, cathodoluminescence microscope, field emission scanning electron microscope and physical property experiments, reservoir space types of calcilutite-rudstone reservoirs in the lower part of Member 3 of Shahejie Formation, Shulu sag, were analyzed systematically, and genesis of reservoir space and its controlling factors were discussed. Five kinds of lithology, i.e., laminated calcilutite, massive calcilutite, grain-supported terrigenous rudstone, matrix-supported terrigenous rudstone and mixed-source rudstone are well developed in this calcilutite-rudstone reservoirs. This kind of reservoir is tight and characterized by extremely poor porosity and permeability, which belongs to low porosity and ultra-low permeability reservoir. Reservoir spaces mainly include secondary pores and fissures, such as dissolution pore, organic-matter pore, intra-gravel pore, intra-particle (crystal)pore, inter-particle (crystal)pore, tectonic fissure, interlayer bedding fissure, gravel-lined fissure, contraction fissure and organic-acid dissolution fissure. Reservoir spaces of calcilutite are dominated by organic-matter fissure, bedding fissure and inter-particle (crystal)pore, while those of rudstone are mainly intra-gravel pore, dissolution pore and tectonic fissure. Development of reservoir spaces are mainly influenced by combined effects of tectonism, sedimentation, provenance and diagenesis.