Sandstone reservoirs in Dongying Sag

the Bohai Bay Basin are rich in feldspar

dissolution of which is very common and has an important influence on reservoir physical properties. Polarizing microscope

SEM and X-ray powder diffraction technologies were used to study the distribution characteristics of feldspar and its dissolution products in the sandstone reservoirs in Dongying sag. The content of feldspar varies in different areas. The highest content of feldspar occurs in the north

followed by the south

and the lowest is in the central area. Vertically

Es1is the richest in content of feldspar

followed by Es2and Es4f

and Es3is lowest. The main dissolution products of feldspar in the sandstone reservoirs in Dongying sag include kaolinite

illite and chlorite. The transformation kaolinite to illite and chlorite causes the decrease of content of kaolinite. The illite and chlorite in the shallow layer are mainly transformed from I / S

while they come from kaolinitic alteration in the deep layer. The content of I / S is high in shallow layer

and reduces with the increasing depth.