根据38口井岩石学、物性等相关资料,研究了广安地区上三叠统须家河组砂岩储层特征,分析了不同含气层岩石类型,探讨了成岩作用对气藏分布的控制。研究区须家河储层岩石类型呈现结构成熟度中等,成份成熟度较低的特点,以岩屑长石砂岩、长石石英砂岩和长石岩屑砂岩为主；从须二段到须六段,岩石成分在变化,岩屑含量逐渐增多；富气砂岩主要为长石岩屑砂岩。砂岩储层物性整体属于低孔、低渗特征,主要发育粒间溶孔、残余粒间孔、粒内溶孔,其中粒间溶孔、残余原生粒间孔发育程度的好坏直接影响到储层的储集能力。研究区存在石英加大—绿泥石衬边、石英加大—溶蚀、绿泥石衬边—溶蚀、绿泥石衬边—碳酸盐胶结和石英加大—碳酸盐胶结等6大类成岩相。绿泥石衬边—溶蚀相和石英加大—溶蚀相为最好的成岩相类型,研究区须家河组气井都分布在该2类成岩相中。

Based on the petrologic data，sandstone thin sections and molded thin sections of about 38 wells, this paper describes the reservoir characteristics of the Upper Triassic sandstone reservoirs in the Guang′an gas field, analyzes the different rock type of gas reservoir, discusses diagenesis control on the distribution of gas reservoirs. The reservoirs have the medium texture maturity and lower maturity composition. Reservoir lithology is mainly feldspathic litharenite, feldspar quartz sandstone, lithic feldspar sandstone. The content of debris gradually increases from Xu2 to Xu6. Feldspathic litharenite sandstones are rich in gas. The reservoirs are low porosity and permeability. The main reservoir space includes primary intergranular pores, intragranular pores and intergranular pores (intergranular dissolved pores). The development degree of primary intergranular pores decides the reservoir basic properties. The reservoir has diagenetic facies of quartz secondary enlargement-lining chlorite facies, quartz secondary enlargement-dissolution facies, lining chlorite dissolution facies, lining chlorite-carbonate cementation facies, quartz secondary enlargement-carbonate cementation facies. The lining chlorite-dissolution facies and quartz secondary enlargement-dissolution facies are favorable for reservoir formation.