Low-velocity Zone Of Buried Hills In Lower Paleozoic Group In Zhuang-hai Area Jiyang Depression

Reservoir of oil gas in buried hills is a kind of special bedrock reservoir. It is a prominent oil-bearing object in the older stratum under the surface of unconformity. Its oil-source mainly comes from oil-forming overlying and side direct stratum. Surface of unconformity or fracture is the major channel for movement of oil gas.Earthquake wave velocity changed greatly in diffrernt kinds of buried hill reservoirs. Velocity of carbonatite is usually faster than other kinds of rock. Low-velocity zone in carbonatite is possiblly good reservoir.In all kinds of reservoirs, secondary silicon rock and porosity dolostone are special. Discovery of them is important meaning for exploration of buried hill reservoirs.This paper studies the characteristics of Lower Paleozoic buried hills in Zhuang-hai area of Shengli oi1 field , probes into the sedimentation and geophysical characteristics of Lower Paleozoic buried hills,analyses the function of regional tectonic movement in low-velocity zone. The author research the formative reason of low-velocity zone in Lower Paleozoic buried hills. Emphasize on the form of porosity and silicified stratum. Exert geochemical method to test character of isotope and temperature of inclusion. Conclude that induced-porosity is primary in Zhuang-hai area. Classify the Lower Paleozoic carbonate reservoir of buried hills in Zhuang-hai area. Then the author discusses formative mode of silicified stratum in Zhuang-hai area from analysing single well and karst in studying area.Finally,the author points out the richly producing zone and analyses the relationship between reservoir characteristics and low-velocity zone,Points out the main direction of later exploration. The Paper includes several fresh views that will be useful in later exploration.