oa Total Organic Carbon Evaluation of Heterogeneous Coaly Facies Using Well Logs Data, Carboniferous Lorraine Basin (France).

Continental fluvio-lacustrine coal bearing strata in the Carboniferous of the Saar-Lorraine basin are particularly heterogenous in their distribution. This renders source-rock volume evaluation difficult. This study focuses on the TOC determination along well-log. When cores are available, sample picking and TOC measurements through lab methods is not satisfactory since it generates discontinuous data sets. An alternative method is to use continuous well-log data and calculate TOC using DeltalogR or Carbolog methods. TOC assessment is quite accurate for sandy facies but underestimates values for coaly shales, shaly coals and coals seams. Objectives of this presentation will be to explain why TOC are underestimated for shales and coal seams, how to correct the calculated values and how this impacts the source-rock volumes estimates in these unconventional reservoirs.