黔南、黔北及南盘江坳陷古生代碳酸盐岩储层特征

Reservoir characteristics of Paleozoic carbonate rock in southern and northern Guizhou and Nanpanjiang sags

黔南、黔北及南盘江坳陷发育有相当规模的古生代海相碳酸盐岩沉积,沉积厚度大;重要储层岩性为微晶-亮晶生物碎屑灰岩、藻礁-生物礁灰岩和生物碎屑叠层泥晶灰岩;储集空间类型为原生和次生孔隙:原生孔隙有生物体腔孔、生物骨架孔和原生粒间孔,次生孔隙有晶间孔、粒内溶孔、铸模孔、溶蚀孔和微孔,以及缝合线孔隙和裂隙。本区溶蚀作用形成的次生孔隙增大了储层储集空间,使面孔率达到8.7%,而后期形成的构造裂缝又改善了储层的连通性,提高了储层的渗透能力;从储集空间的配置关系角度对碳酸盐岩储层进行油气资源评价分析,得出黔南坳陷碳酸盐岩储层为I类储集层;南盘江坳陷和黔北坳陷碳酸盐岩储层为II类储集层。

The Paleozoic carbonate reservoir rocks are developed widely in the studied area, which are big in thickness of deposit. The main reservoir rocks are micrite and sparite with biological detritus, algal reef and biolithite, nappe micrite with biological detritus through studying of the carbonate reservoir rocks. The reservoir space types in the area include primary pores and secondary pores, of which the primary pores are composed of biological coelome pore, biological framework pore, primary intergrain pore, while secondary pores include intercrystalline pore, intragranular dissolved pore, mold pore, corrosion pore, micropore as well as stylolite pore and fissure. The secondary pores produced by corrosion in the area increased the reservoir space dramatically, which resulted in the percent of area pores increasing to 8.7 %. The telogenetic structural fracture improved the connectivity of the reservoir and its permeability. The carbonate reservoir in southern Guizhou sag is Ⅰ-type reservoir, the northern Guizhou- and Nanpanjiang sags belong to Ⅱ-type reservoir based on the analysis of space distribution of reservoir.