Coupling Relationship between Multistage Fluid Activity and Reservoir Abnormally High-Porosity Zones in the Songtao–Baodao Region, Qiongdongnan Basin

Table 1

Diagenetic stages in the Yacheng region of the Qiongdongnan basin.

Diagenetic stage			Now geothermal temperature (°C)	Ro (%)	TAL	Tmax (°C)	Maturity	S (%)	I/S mixed layer type	Pore type	Depth (m)
Early stage	A	Early compaction and cementation	80	0.35		405	Immature	70	Smectite	Primary pore	1600
	B	Early dissolution	115	0.5	dark-orange yellow 2.6-2.8	425	Half mature	40	Chaotic mixed	Secondary pore	2400
Middle stage	A1	Middle dissolution	140	0.7	dark-orange yellow 2.8-3	435	Low mature	25	Order mixed		3200
	A2		195	1.3	dark yellow-light brown 2.8-3	455	Mature	10	Superlattice order mixed		4500
	B	Late dissolution	>195	>1.3		>455	High mature	5			>4500