Three Levels of Well Log Data Interpretation In Geomechanical Modelling

Historically, standard log data interpretation has been required for geological modelling, while rock physics modelling and analysis traditionally prepare the foundation for seismic inversion, since rock physics is used to determine relationship between elastic parameters and reservoir properties of porous rock types. This is different for complex unconventional reservoirs, where matrix component contributes a small part to the overall productivity. In this case geomechanical parameters become more important for further field development of complex unconventional reservoirs: initial principal stresses in the rock, brittleness, changes of rock properties after hydraulic fracturing. In this case the role of seismic inversion is lessened to the prediction of elastic parameters between wells to progress the transition to a geomechanical model, calibrated to well data. The role of interpretation of well log data is fundamental in this process and includes three stages: the first stage is petrophysical interpretation to obtain a bulk petrophysical model, then petrophysical model is built for recovery and correction of compressional and shear velocities, finally, the last stage is determining relationship between elastic and geomechanical parameters. The suggested approach allows to constantly account for changes in the formation parameters in field development process and to make adjustments to geomechanical model accordingly.