The first phase of any hydraulic fracturing (HF) operation is to select carefully the best layers and wells based on a specific set of criteria. Selecting HF candidates plays a pivotal role in achieving the desired objective such that any attempt to execute this treatment fails without performing comprehensive studies in this regard. In this paper, data from 3 wells in a fractured carbonate reservoir in one of the biggest oilfields of Iran are studied for selecting the best HF candidate. Of these wells, which are comprised of 45 evaluated layers, the best candidate wells/layers are selected from a geomechanical point of view. Initially, a new fracability index appropriate for carbonate reservoirs, namely total fracability index (TFI), is defined. This index integrates mechanical properties and horizontal stresses into an equation. In the next step, four main criteria, namely layer thickness, TFI, natural fractures state (including orientation and density), and fracture confinement, are employed to choose the candidate layers in the wells. Lastly, having used these criteria and analytic hierarchy process, candidate intervals are selected and a hydraulic fracturing simulation model (P3D) is used for evaluation.