碎屑组分差异对成岩作用的约束——以苏里格气田东二区砂岩储层为例

成岩物质基础的不同是否能在一定程度上影响成岩微环境、成岩矿物和成岩强度，是一个值得深入探讨的问题。为此，以鄂尔多斯盆地苏里格气田东二区二叠系砂岩储层（位于盆地北部两大物源分区的交汇部位，其主要含气层段为下二叠统山西组一段和和下石盒子组盒8段）为例，采用薄片鉴定、铸体、阴极发光、扫描电镜、流体包裹体激光拉曼等分析实验方法，深入研究了长石石英砂岩和岩屑砂岩在成岩流体性质、成岩微环境和成岩产物等方面的差异。结果表明：①该区砂岩储层成岩现象多样，不同的岩石类型成岩序列也不同；②储层中成岩古流体的演化复杂，具有多流体性质和成岩环境变化相叠合的特点，在不同的砂岩类型中具有不同的表现；③埋深和温度是该区储层成岩环境变化的主导因素，此外，岩性及原始物质组分的差异不仅影响了局部流体性质和成岩微环境的变化，而且还导致了成岩反应、成岩序列和成岩产物的差异；④受差异成岩作用控制，该区长石石英砂岩的成岩演化相对简单，其孔隙特征明显好于岩屑砂岩。

Constraints of clastic component difference on diagenesis : A case study of sandstone reservoirs in Dong-2 Block of the Sulige Gasfield,Ordos Basin

〗It is necessary to discuss if diagenetic micro-environments, minerals and intensities can be, to some extent, influenced by diagenetic material basis. In view of this, a case study was performed on the Permian sandstone reservoirs in Dong-2 Block of the Sulige Gasfield, which is located in the intersecting part of two major material source subzones in northern Ordos Basin. The main gas-bearing intervals are the 1^st Member of Shanxi Formation and the 8^th Member of Lower Shihezi Formation in Lower Permian. Thorough analysis was conducted on the difference of diagenetic fluid properties, micro-environment and products between feldspathic quartzose sandstones and lithic sandstones by means of thin section analysis, cast, cathodeluminescence, scanning electron microscope, fluid inclusion laser Raman methods. It is shown that there are various diagenesis in sandstone reservoirs in this area and diagenesis sequences vary with rock types. Diagenetic paleofluids in the reservoirs have experienced complex evolution and present superimposition features of both multi-fluid properties and diagenetic environment change, whose appearance varies with sandstone types. The diagenetic environment of the reservoirs in this area is mainly controlled by burial depth and temperature. And moreover, the differences of lithology and original material components not only affect the change of local fluid properties and diagenetic micro-environment, but result in the diversity of diagenetic reactions, sequences and products. Under the effect of differential diagenesis, the feldspathic quartzose sandstones in this area experienced relatively simple diagenetic evolution and are better in pore characteristics than lithic sandstones.