Abstract:

The sandstone reservoirs containing pore-lining chlorite are commonly high-quality reservoir which is believed to be due to the pore-lining chlorite by weakening authigenic quartz cement growth on detrital grains. Based on the source of iron, the formation mechanism of pore-lining chlorite consists of transformation of precursor clay minerals, direct precipitation from iron-rich substance dissolution, and mixture of precursor clay and direct precipitation. Comparative study of domestic and foreign sandstone reservoirs with abundant pore-lining chlorite shows that the pore-lining chlorite can influence reservoir quality by retarding authigenic quartz cement growth，enhancing sandstone resistance ability to compaction, indicating the degree of early alkaline dissolution and blocking pore throat. The influence way and degree on reservoir are determined by chlorite genesis and diagenetic stage. Before period A of middle diagenetic stage, the transformed chlorite affects sandstone reservoir quality by suppressing quartz overgrowth and raising sandstone resistance ability to compaction, and the direct precipitation chlorite affects by indicating the degree of early alkaline dissolution. After accessing to period B of middle diagenetic stage, the pore-lining chlorite show full ability to weaken quartz cementation in sandstone reservoirs.

Key words: chlorite, reservoirs, dissolution, sandstone, diagensis