Predicting S-Wave Velocity from Wire-Line Logs for Organic-Rich Rocks

Lacking of S-wave velocity in logging will negatively affect the process of reservoir prediction and formation evaluation for organic rich rock reservoir. In this paper, a simple but effective method is presented to predict the S-wave velocity from P-wave velocity based on the combination of the critical porosity consolidation coefficient (CPCC) model with dual-variable parameters and quantum particle swarm optimization (QPSO) algorithm. In the presented method, the P-and S-wave velocities of organic-rich rock are linked by consolidation coefficient and critical porosity. Then, the error between the measured and calculated P-wave velocity is used to establish the inverse objective function. Moreover, the QPSO algorithm is introduced to invert the critical porosity and consolidation coefficient. Finally, the S-wave velocity can be predicted using the inverted parameters. Compared with two existing single-parameter adaptive methods, the predicted S-wave velocity of the proposed method is superior, which can be satisfactorily implemented for laboratory measurement and on logging data.