Abstract: The complexity of volcanic reservoir rock component,structure,and gas-water relationship,multiplicity and highly uneven random distribution of pore space result in the strong heterogeneity,low porosity and low permeability of the reservoir,so gas identification is always a challenge to logging reservoir evaluation.In this paper,NMR-density logging method,synthetic S-wave logging overlapping,compression coefficient-Poisson ratio overlapping and pressure gradient method are adopted to identify gas layers in igneous reservoir,and good effects have been achieved in the identification of the fluid property in Songnan gas field.Research shows that the response mechanism of the logging methods in different pore-fracture system is different,resulting in significant difference in result of natural gas identification.For different reservoir characteristics,different gas layer identifying methods are used,and better identification result can be achieved in igneous reservoir.

Key words: volcanic rock, natural gas, reservoir evaluation, NMR, logging interpretation