FRACTURE-CAVE SYSTEM AND PETROLEUM DISTRIBUTION IN ORDOVICIAN IN MAIN REGION OF TAHE OIL FIELD

Macroscopic tectonic evolution and microscopic fluid geochemistry studies have proved that,petroleum distribution in the Tahe Oil Field is controlled by tectonic framework formed by combination of early and late Hercynian movements.Superposition of ancient structures controls generation of palaeo-geomorphology and fracture.Generation of palaeo-geomorphology and fracture controls ancestral rive orientation and erosion depth.They are the main controlling factors of karst effect.Especially in the superposition of ancient structure formed during late Hercynian and axle of the Akekule Uplift,karst and fracture generate in large scale.Commonly-found large angle fractures connect caves into large reserve,resulting in horizontal division of large fracture-cave system in main region of the field.Based on fluid heterogeneity and macroscopic tectonic evolution analysis in Ordovician in main region of the Tahe Oil Field,2 large and 1 middle-small fracture-cave systems are divided.