四川盆地雷口坡组三段颗粒滩储层特征及成因分析

Characteristics and genetic analysis of grain shoal reservoirs in Lei 3 member of Middle Triassic Leikoupo formation,Sichuan Basin

通过对钻井、录井、测井及岩心等地质资料的综合分析,对四川盆地中三叠统雷口坡组三段颗粒碳酸盐岩储层特征及成因进行研究。结果表明:残余粒间孔保存型储层和同生期岩溶型储层是研究区雷三段颗粒碳酸盐岩储层的两种主要成因类型;残余粒间孔保存型储层以残余粒间孔和粒间溶孔为主要的储集空间,管状喉道和缩颈喉道发育,较好的孔喉配置关系使储层多表现为中孔中渗、储渗能力较好的特征;同生期岩溶型储层以孤立的粒内溶孔和铸模孔为主要储集空间,喉道欠发育,中孔微喉的配置关系导致储层多表现为中孔低渗、渗透性偏低的特征;分别形成于台地边缘和台地内部的颗粒碳酸盐岩为两种颗粒滩储层的形成提供了早期物质基础;单滩体的厚度直接控制着两种颗粒滩储层的储渗形式;成岩演化是两种颗粒滩储层定型的关键。

The characteristics and genesis of grain shoal carbonate reservoirs were studied by using the data of drilling, log-ging and core in Lei 3 member of Middle Triassic Leikoupo formation in Sichuan Basin. The results show that the residual in-tergranular preservation reservoirs and syngenetic karst reservoirs are the main genetic types of grain shoal carbonate reser- voirs. Residual intergranular pores and intergranular dissolved pores are main reservoir space of residual intergranular preser-vation reservoirs, and tubular throats and neck throats are developed. Relatively good configuration of the pore throat leads to the characteristics of medium porosity and medium permeability and good capacity. The isolate intragranular corroded pores and mould pores are main reservoir space of syngenetic karst reservoirs, and throat is less developed. Configuration of medi- um pore and micro-throat leads to the characteristics of medium pore and low permeability. The grain carbonate developed in the marginal platform and interior platform provides the early material basis for the two types of grain shoal reservoirs. The thickness of a single shoal body directly controls the reservoir and permeation form of the two types of grain shoal reservoirs. Diagenetic evolution plays a key role in finalizing the shape of the two types of grain shoal reservoirs.