Abstract:

The effect of diagenesis on pore structure of sandstones in third oil layer of Xingouzui Formation in Tuoshi area,Qianjiang Depression is discussed in this paper.The compaction and cementation decreased the pore throat and pore radius of the sandstones in different degrees,and caused the pores to disintegrate into micropores and intercrystal pores,the throats into schistose throats and tubebundle throats in sandstones.The dissolution increased the pore throat and pore radius of sandstones,turned the pores into coarse ones and tubular throat.The compaction resulted in better pore sorting,but the cementation and dissolution made it more complicated.In sandstones of compaction type and cemetation type,the permeability contributed peak position is inconsistent with that of the pore distribution peak position,and their permeability for air is usually less than 1 thousandth of square micron and devoted by few pore spaces with radius bigger than 8 micron.In sandstones of dissolution type,the permeability devoted peak position is usually consistent with that of the pore distribution,thus the main pore spaces of the sandstones are vadose pores.