Abstract:

Kaolinite widely distributed in the sandstone reservoir of the Shahejie Formation in Dongying depression，which is an important factor affecting the reservoir physical properties. But the research on its distribution characteristics and controlling factors is less comparatively. This paper goes on to research the distribution characteristics and controlling factors of kaolinite by analyzing the data from casting lamella，X-ray diffraction，cathode luminescence image，electron scan microscope. Research results show that kaolinite mainly developed in the range of depth 1，200一3，600 m. The average relatively content of kaolinite are much higher in Es₂ and Es ₃ .As to the kaolinite content in Es₁ to Es₃，the central uplift belt is higher than northern steep slope and southern ramp zone of Dongying depression. Distribution of kaolinite in the sandstone reservoirs of Shahejie Fororation is obviously affected by thermal evolution of organic matter. Different temperatures(buried depth)affect the content of kaolinite in different horizons of Shahejie Formation and its distribution in plane and profile by controlling the formation and transformation of clav minerals .The overpressure has an important influence or the distribution of kaolinite. Due to overpressure，the overpressured top boundary is generally characterized by well-developed kaolinite. Tectonic activity of central uplift belt of Dongying is strong，which is advantageous to the acidic fluid from deep to shallow filling. And hydrodynamic force is strong，leading to kaolinite content in Es₁ to Es₃ of the central uplift belt is higher. The pathway system composed of fault and unconformitv surface transport a large number of acidic fluid into the shallow reservoirs，which lead to considerable development of kaolinite. Lithology and sedimentary microfacies change the fluid chemistry and hydrodynamic conditions，thus has an important influence on kaolinite distribution.

Key words: kaolinite, distribution characteristic, influencing factor, Dongying depression, Shahejie Formation