Relations of P-wave velocity with porosity, shale content and water saturation gas zone

Based on the analysis of logging data, it is found that effect of porosity and shale content on acoustic velocity is heavier than that of water saturation on it. But, if gas exists in rock with low porosity and low permeability, relation between P-wave velocity and water saturation should be considered differently in view of lithology. In addition, accuracy of porosity derived from S-wave velocity is lower than that from P-wave velocity with the present methods. Therefore, the porosity obtained from S-wave should be used cautiously.