Solution pores are the main reservoir space of Fuyu reservoir in Fuyu-Xinli region. They are mainly particle solution pores

filler solution pores and particle-filler solution pores. The acid components that resulted in the solution pores were provided by organic matter which resulted from kerogen deacidify

thermo-catalysis and thermo-transformation in middle diagenesis from overlain dark mudstone and shale of the first member of the Qingshankou Formation.The formation of the pores is not only effected by original texture and composi-tion of sand beds

but also closely related to rigional structure position (such as syngenetic structure apex)

faults and fractures. A stable and appropriate tectonic condition may be particularly favourable for long term seepage and complement of acid water

and may result in various kinds of solution pores

especially feldspar pores.