2014 Rocky Mountain Section AAPG Annual Meeting

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Serendipity, Sandstone, and Shale in a Revitalized San Juan Basin


The San Juan Basin is experiencing an oil and gas industry revitalization as the result of completions in unconventional reservoirs in the Mancos Shale and Gallup Sandstone formations. Legacy drilling and completion operations have targeted conventional reservoirs in both the Mancos and Gallup formations for decades. Presently, the application of new technology is fueling development in previously bypassed pays in these formations. While the Mancos Shale and Gallup Sandstone reservoirs were deposited relative to the same shoreline in the Cretaceous Western Interior Seaway, they differ in depositional environment and reservoir characteristics. Serendipitously, Mancos source rock changes phase from volatile oil to dry gas coincident to changes in the nature of the reservoir. This talk will discuss the regional interplay between the changes in source rock maturity and regional stratigraphy in the San Juan Basin Mancos and Gallup Formations.