Abstract:

In Maling oilfield and its vicinity,the process of pore evolution in Yan-10 sandstones of Jurassic during diagenesis is discussed in this paper.The main conclusion proposed are as follows:1)The pore evolution is in fact a process of gradual substitution of secondary pores for the primary ones;2)The decrease of porosity in quartz arenites is mainly due to the precipitation of authigenic minerals in the sandstone pores during diagenesis;while the decrease of porosity in arenites with more flexible component is mainly caused by compaction during diagenesis;3)The secondary solution pore mainly developed after its diagenetic stage by dissolution and kaolinization in arenite which is abundant in feldspar.This process is likely to be related to the decarboxylation of organic matter in interbedded coal seams and carbonaceous shales by thermalizatin;4)The clastic constituents of sandstone controlled by source materal distinctly affect the development of pores.Therefore,the primary and secondary pores in sandstones favourable can be predicted on the basis of finding out the source material of sediments;5)Diagenesis obviously affects on the texture and the uniformity of pores in sandstones.