THE DIAGENETIC EVOLUTIVE LAW OF DEEP BURIAL STRATA AT SHAHEJIE FORMATION IN EASTERN AND WESTERN DEPRESSIONS OF LIAOHE OIL FIELD

The development of secondary porosity of sandstones has evidence law at deep burial strata of Shahejie Formation in eastern and western depressions of Liaohe oil field. The eastern depression has three secondary porosity zones in vertical, but western only two. The secondary porosity zone of the second member lower to the third member top of Shahejie Formation, viz the upper secondary porosity, is the result of leached by surface fresh water and integrated process along unconformity interface later period by inorganic acid in open water circulation. The mechanism of lower two zones of secondary porosity is similar to two secondary porosity in western depression which silicate mineral had been made solution by organic acid in seal water circulation. The geological conditions of these two zones forming are following as:temperature is about 100 to 130 Celsius, pressure coefficient is 1.2 to 1.3 around, the phase and depth are during source rock had made abundant expulsion hydrocarbon.