In 1998, Burlington Resources (BR) initiated a study to characterize the Lewis Shale (Lewis) gas potential in the San Juan Basin (SJB) and optimize exploitation. Historically, most SJB production has been from naturally fractured, low permeability, Cretaceous sandstones (Dakota, Mesaverde, and Pictured Cliffs) or from the prolific Fruitland Coal. In the past, the Lewis, which lies between the Mesaverde and Pictured Cliffs Formations, was completed in only the few wells where large Lewis flow rates were encountered while air-drilling for deeper targets. However, the Lewis lies behind pipe in thousands of existing wells across the SJB. In a large number of these wells and in new Mesaverde/Dakota wells, the Lewis can be completed. The BR program includes performing geological, petrophysical, reservoir, stimulation, and production data analysis. From this data, reservoir characterization, completion optimization, and forecasting models were developed that indicate commercial Lewis potential through much of the SJB in both new and existing wells. Furthermore, the Lewis is more accurately characterized as a sandy siltstone, rather than a true shale such as the Devonian or Antrim Shale.

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