The carbonate rock reservoir on the northern slope of Yingshan Formation

Tazhong uplift

has undergone multistage diagenetic modifications of various kinds

featuring large thickness and deep burial depth.Based on the observation of core and thin section

the interpretation of well-logging data and the fracture identification by seismic attribute inversion

combined with the statistical analysis of logging and formation testing data

we found that the karst reservoir of the Yingshan Formation has gone through multistage dissolution and tectonic fracturing

and the reservoir space has experienced intensive

constructive rework

while the destructive cementation-filling is relatively weak.In comparison

the adjacent tight interval is mainly caused by intensive cementation and filling

and because the interval is remarkably weak in dissolution

its electric resistivity is significantly higher than that of adjacent reservoir intervals.So it is called "high-resistivity interval"

a diagnostic character to identify tight layers.There are significant differences in diagenesis between the carbonate reservoirs and its adjacent tight caprocks.It is the differential diagenesis that results in the formation of multiple reservoir-caprock assemblages inside thick-bedded carbonate units.Vertically

multiple fracture-cavity sections (reservoir) alternate with tight sections (caprocks)

having formed multiple superimposing reservoir-caprock assemblages.This has led to multiple hydrocarbon-bearing zones in the thick-bedded carbonate unit.Horizontally

due to the heterogeneity of carbonate rocks and the segmentation of strike-slip faults

the distribution of both karst reservoirs and tight high-resistivity caprock is restricted

leading to the hydrocarbon accumulation pattern in the Yingshan Formation characterized by vertical zonation and lateral compartmentalization.