Characteristics and petrophysics experiment of low-poros-ity and low-permeability sandstone reservoir

With the extension of petroleum exploration and devel- opment,the proportion of low-porosity and low-permea- bility reservoir takes more and more advantageous position. The low-porosity and low-permeability sandstone reser- voir is of high compaction degree and of complicated diagene- sis.Therefore,it is hard to match the geologic interpretation model with the logging interpretation model.The study indi- cates that the formation and the evolution of its porosity are dominated by the diagenesis.And the diageneses mainly comprise the cementation,the compaction and the dissolu- tion.Among the diageneses,the cementation and the com- paction are unfavorable to the pore evolution,while the dis- solution is favorable to the formation of secondary pores.On the basis of petrophysics experiments,a study is performed on the relation of formation factors of the low-porosity and low-permeability sandstone reservoirs with porosity,re- sistance increase rate and oil saturation,and on the character of NMR (nuclear magnetic resonance)cross relaxation (T2 spectrum).Through contrast analysis on the low-porosity and low-permeability reservoir with regular one,the partic- ularity of the physical properties of the low-porosity and low-permeability reservoir is presented,which provides a scientific basis for obtaining accurate logging interpretation.