Acoustic Velocity Study of Low Porosity and Low Permeability Reservoir Based on Gas Inclusion Model

According to the evaluation difficulty of middle-deep gas reservoir with low porosity and low permeability, the study of rock physics using modified White gas inclusion model is carried out in this paper. Firstly, the gas inclusion model is analyzed to get the calculation formula of P-wave and S-wave velocity. Then, the parameters of acoustic velocity, porosity, saturation, pressure and temperature are theoretically calculated. Finally, the calculated results are verified by laboratory experiments. This study indicated that P-wave velocity changed obviously with the water saturation variation, and S-wave velocity changed slightly with the water saturation variation. Compaction makes the P-wave velocity increases rapidly and the S-wave velocity increases slowly, which is caused by the changes of elastic modulus and shear modulus. Effect of temperature on the acoustic velocity can be neglected. The study of this paper can provide technical support for the acoustic wave velocity measurement and interpretation of complex reservoir with low porosity and low permeability.