[This article belongs to Volume - 47, Issue - 02]

Characteristics and comparison of karst reservoirs of lower Paleozoic in Nanpu Sag and outcrops

The carbonate buried hill in Nanpu Sag is an important deep oil and gas exploration field with deep burial and old age., complex tectonic movements and the characteristics of multi-stage karstification. Based on the drilling, core, logging and seismic data of outcrops around Tangshan and Nanpu Sag, the characteristics of karst reservoirs in outcrops and sag were compared and analyzed. The results show that: outcrops around Tangshan and Nanpu sag The Lower Paleozoic structural-karst background in the sag is basically consistent and has good contrast. The typical fault-controlled karst reservoirs and karst collapse bodies in the outcrops provide reference for the karst reservoirs in the Nanpu sag; the karst reservoirs in the Nanpu sag have fault-controlled and The collapse has dual characteristics. The reservoir is located in the rising plate of a high-angle tensile-torsion fault. Affected by the combined collapse, the karst reservoir range can reach 170 m below the unconformity surface. There are no obvious voids in the reservoir section, with increased fracture density and natural acceleration. The characteristics of horse rising and increasing mud content; there are various types of fracture-cavity filling materials, collapse breccia and clast-filled sand and mudstone are more common. Different types of fracture-cavity filling materials have a greater impact on the physical properties of the reservoir, among which clastic filling materials The physical properties are good; fault-controlled karst and combined collapse can form a pore-fracture-cavity composite reservoir space system.