The analysis of the geological and petrophysical characteristics of a subsurface reservoir is the primary purpose of most core studies. However, a thorough reservoir analysis requires the integration of core and log data, as there are often uncored intervals and uncored wells within a reservoir. This integration should begin with a key well where high quality data from both sources are available. With newly drilled wells the well-site examination of core or well cuttings can be an input to an improved interpretation of log measurements. The log study can give an insight which allows an efficient and effective study of the geological and petrophysical characteristics of a core or reservoir.