伦坡拉盆地牛堡组砂砾岩致密化与孔隙成因

依据岩芯、薄片、物性和扫描电镜等资料，开展伦坡拉盆地牛堡组砂砾岩储层岩石学及储集特征研究，着重从成岩角度分析了储层致密化因素，结合孔隙形成的有利因素，开展成岩作用和石油充注的关系及顺序研究，首次探索了储层孔隙的发育过程。结果表明，砂砾岩储集空间以残余孔隙为主，混积的沉积环境、较弱的抗机械压实能力和中晚成岩期碳酸盐的强烈胶结是导致储层致密的3大因素，酸性流体对易溶颗粒的溶蚀是次生孔隙形成的主要因素，石油充注是孔隙保存的有利因素，主要表现在石油充注使部分孔隙溶蚀扩大，并在孔隙周缘形成油膜抑制碳酸盐胶结；压实作用在浅埋藏阶段对储层的破坏较大，随埋深增大，酸性溶蚀、石英次生加大及石油充注发生，之后，早期碳酸盐胶结物形成，成岩中晚期含铁碳酸盐胶结物交代早期碳酸盐矿物，堵塞了大部分孔隙，晚期的构造挤压使储层形成裂缝。孔隙的形成经历了原生粒间孔隙形成，压实作用减孔，酸性溶蚀扩大孔隙，石油充注保护孔隙，碳酸盐胶结破坏孔隙等过程，石油充注较充分与碳酸盐胶结较弱的叠合区是孔隙保存的有利区。

Glutenite Compaction and Pore Formation in the Niubao Formation,Lunpola Basin

This study investigated the lithology and reservoir characteristics of the glutenite reservoir in the Niubao Formation of the Lunpola Basin using core, thin section and physical property analysis, and SEM data. In particular, several factors of rock compaction were analyzed from the viewpoint of diagenesis, and the relationship and sequential order between diagenesis and oil emplacement was investigated with reference to favorable conditions for pore formation. This study investigates for the first time the developmental process of reservoir pores. The results show that the reservoir space mainly comprises residual pores. A mixed sedimentation environment, relatively weak resistance to mechanical compaction, and intense carbonate cementation in the mid-late diagenetic phase are the three leading causes of reservoir compaction. Dissolution of soluble parties by acidic fluids is the main factor controlling the formation of secondary pores, whereas oil emplacement favors porosity preservation in that it causes dissolution and enlargement in some pores and forms oil films in the periphery to prevent carbonate cementation. Compaction causes significant damage to the reservoir during the shallow burial stage. As burial depth increases, acid dissolution and quartz overgrowth are enhanced and oil emplacement takes place. These lead to the formation of early carbonate cements. In the mid-late diagenesis, iron-containing carbonate cements replace early carbonate minerals and block most of the pores. The late-stage tectonic compression that follows leads to cracking in the reservoir. Based on the above, it can be concluded that pores are first formed among the primary grains, and then eliminated by compaction. Acid dissolution enlarges the pores, while oil emplacement preserves porosity and carbonate cementation destroys pores. The overlap between regions with sufficient oil emplacement and those with weak carbonate cementation is favorable for porosity preservation.