The paper presents analysis of geo-temperature, hydrodynamic and hydrogeochemical data in comparison with the complex results of geological, geophysical, paleontological, geochemical and other studies in assessment of the petroleum potential of Mesozoic sediments in the Karabash zone. The results obtained indicate a low efficiency of the traditional hydrogeological criteria application for the zone under consideration, due to the unevenness of the deposits study, small ranges of changes in hydrogeological indicators and the use of many different criteria. Under these conditions, the task of developing methods for a comprehensive analysis of all hydrogeological data becomes urgent.