Comparison of Diagnostic Tools for Selecting Completion Intervals in Devonian Shale Wells

Abstract

Commonly available tools used by producers for selecting intervals for stimulation provide different, and sometimes conflicting, information on which zones have the best potential to produce gas. Data on the presence of hydrocarbons and permeable features required for migration of hydrocarbons to a well can be acquired from mud logs, noise and temperature logs, borehole television logs, and geophysical well logs. The Gas Research Inst. (GRI) has funded the collection of these data in more than 30 Devonian shale wells as part of its Eastern Devonian Gas Shales project area, permitting an evaluation of the utility of these diagnostic tools for selecting treatment intervals. Special interpretive methods were developed for analyses of data from geophysical logs, borehole television logs, and experimental mud-logging techniques. Data from each technique were analyzed to determine the geologic and reservoir characteristics of the zones with gas production potential. Production logs were collected in the study wells after stimulation and cleanup to determine the relative contribution of each completed zone to the total production of the well. The comparison of actual productivity of each completed zone to the anticipated gas potential as indicated by each diagnostic technique can provide producers with a better understanding of howmore » to interpret and use the diagnostic data collected during drilling and completion of Devonian shale wells.« less