Application of DSI Log in Geomechanical and Petrophysical Evaluation of Carbonate Reservoirs: A Case Study in One of the SW Iranian Oil Fields

Carbonate formations are typically heterogeneous and anisotropic; hence, dipole sonic logs have great efficiencies in evaluating their geomechanical and petrophysical parameters. In this study, the various uses of DSI logs and processing approaches of its modes are presented as a case study in one of the SW Iranian fields. For this purpose, data from three modes (i.e. 3, 4, and X-dipole) of DSI logs, conventional logs, image log and porosity-permeability core data have been used. Moreover, using the DSI log data, it has been found out that stress state in the studied well is strike slip-normal, and the pore pressure is close to the hydrostatic pressure. In addition, regarding to the wellbore breakouts, the maximum horizontal stress direction is to NE-SW. Moreover, the fast shear wave azimuth is often aligned with the maximum horizontal stress direction. Furthermore, using the DSI log data, energy, traveltime and Dt anisotropies were calculated. The Dt anisotropy increases in fracture and washout zones and traveltime anisotropy which is affected by washouts. In this study, the factors which affect the reflection of the Stoneley waves, and the chevron patterns creation, have been investigated. Also, the most important factor in this case is the wellbore washouts. Finally, it has been found out that the Stoneley permeability has a relatively good correlation with the core permeability.