苏里格气田储集层成岩作用及有效储集层成因

苏里格气田盒8段、山1段为河流相低渗透储集层，具有典型煤系地层成岩作用特征，强烈的压实作用是导致低渗的主要原因，有效储集层为低渗砂岩背景上的相对高渗单元。苏里格气田相对高渗储集层单元与砂岩岩石组构和成岩作用密切相关，沉积水动力条件控制砂岩结构和成分的分异，进而控制成岩作用和孔隙发育特征。粗砂岩石英颗粒和石英岩屑含量高，抗压实能力强，有利于原生孔隙保存和次生孔隙形成，从而成为优质储集层；中细砂岩塑性岩屑含量较高，呈致密压实相，不利于原生孔隙保存和次生孔隙形成，为差储集层或非储集层。将苏里格气田储集层划分为6种成岩相类型，建立了成岩相与沉积微相、沉积序列特征的关系，可预测有效储集层的空间分布规律。图4表1参7

Diagenesis and genesis of effective sandstone reservoirs in the Sulige Gas Field

The He 8-Shan 1 reservoirs in the Sulige Gas Field compose basically of low permeability fluvial sandstone with the coal-bearing stratum diagenetic patterns. The strong compaction is the main reason for the low permeability and the effective reservoirs are those units with relatively high permeability. The depositional hydro-dynamics controls the structure and components of the sandstone, and then, the following diagenetic processes and porosity evolution. The coarse sandstone prove relatively high reservoir quality, with high content of hard quartzite clasts and quartz grains, which favored the preservation of primary pores and occurrence of secondary pores. The medium and fine grain sandstone are poor or none reservoirs, with high content of soft lithic fragments, which led to tight compaction, poor preservation of primary pores and poor development of secondary pores. Six lapidofacies are classified in the Gas Field. The distribution of effective sandstone can be predicted through the integrated studies of lapidofacies and sedimentary microfacies.