Predicting Gas Production in the Marcellus Shale From Sedimentological and Tectono-Stratigraphical Variations in East Lycoming, NE Pennsylvania, USA

Abstract

The Marcellus Shale gas play accounts for nearly 40% of all shale gas production and over 18% of all natural gas supply in the USA. However, exploration and development wells in the play have had mixed results. Improved integration of the sedimentological, tectono-stratigraphical and petrophysical properties of the shale successions with production data is key to understanding the controls on gas production. Using electrical logs data from the Lycoming area, core data, seismic data and the results of laboratory analysis, 11 different Marcellus shale facies types were identified on the six available core data. Calibration of the interpreted facies type against electrical logs and total organic content (TOC) data aided the identification of areas with favorable TOC development, hence improved source rock efficiency and areas with lower clay content and higher calcite content, increased brittleness and thus better reservoir efficiency. Where the basal Marcellus (M1) portion of the Union Springs Member of the Marcellus Shale is dominated by non-calcareous mudstone and pyritic siliceous mudstone facies, higher TOC was observed and better source rock efficiencies were interpreted. Where the upper part (M2) of the Union Springs Member is dominated by calcareous-siliceous mudstone and calcareous pyritic-siliceous mudstone facies, lower clay contents and higher calcite contents were observed and better reservoir efficiencies were interpreted. Trap effectiveness issues associated with the depth of burial and the structural complexities involving the basal Marcellus (M1) was also found to be an important driver of gas production. Where M1 is thin or undeveloped and/or M2 is thin and/or where the Union Springs Member has been negatively impacted by pre-existing structures created by the Taconic, Acadian or Alleghanian orogenies, wells with poor gas production or higher water influx were observed. This study suggest that it is possible to predict source rock efficiency (resource concentration) and reservoir efficiency and trap effectiveness (deliverability) by understanding the facies variations and the tectono-stratigraphic variations within existing well-bores and that such knowledge can be used to predict production away from existing well-bores. The integration of the production predictions with actual production data normalized for completion practices shows that there is a connection between Marcellus shale sedimentology, tectono-stratigraphy and gas production.

AAPG Datapages/Search and Discovery Article #90259 ©2016 AAPG Annual Convention and Exhibition, Calgary, Alberta, Canada, June 19-22, 2016