General screening criteria for shale gas reservoirs and production data analysis of Barnett shale

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2009-05-15

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Shale gas reservoirs are gaining importance in United States as conventional oil and gas resources are dwindling at a very fast pace. The purpose of this study is twofold. First aim is to help operators with simple screening criteria which can help them in making certain decisions while going after shale gas reservoirs. A guideline chart has been created with the help of available literature published so far on different shale gas basins across the US. For evaluating potential of a productive shale gas play, one has to be able to answer the following questions:

  1. What are the parameters affecting the decision to drill a horizontal well or a vertical well in shale gas reservoirs?
  2. Will the shale gas well flow naturally or is an artificial lift required post stimulation?
  3. What are the considerations for stimulation treatment design in shale gas reservoirs? A comprehensive analysis is presented about different properties of shale gas reservoirs and how these properties can affect the completion decisions. A decision chart presents which decision best answers the above mentioned questions. Secondly, research focuses on production data analysis of Barnett Shale Gas reservoir. The purpose of this study is to better understand production mechanisms in Barnett shale. Barnett Shale core producing region is chosen for the study as it best represents behavior of Barnett Shale. A field wide moving domain analysis is performed over Wise, Denton and Tarrant County wells for understanding decline behavior of the field. It is found that in all of these three counties, Barnett shale field wells could be said to have established pressure communication within the reservoir. We have also studied the effect of thermal maturity (Ro %), thickness, horizontal well completion and vertical well completion on production of Barnett Shale wells. Thermal maturity is found to have more importance than thickness of shale. Areas with more thermal maturity and less shale thickness are performing better than areas with less thermal maturity and more shale thickness. An interactive tool is developed to access the production data according to the leases in the region and some suggestions are made regarding the selection of the sample for future studies on Barnett Shale.

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