New Mexico Geological Society Annual Spring Meeting — Abstracts

In September 2016, Apache Corporation announced the discovery of the giant Alpine High oil and gas field in western Reeves County, Texas, about 30 miles north of the town of Alpine. They estimated 3 billion barrels of oil and 75 TCF gas, the largest find ever in the lower United States. Seventeen wells had been completed, mostly in the Devonian Woodford and Mississippian Barnett Shales. The wells produce in the oil and wet gas window at depths between 8,000 and 13,000 feet. Additional pay zones are thought to exist in the shallower Permian Bone Springs and Wolfcamp and in Pennsylvanian black shales, for a total of 5,000 feet of potential pay. The Alpine High is along the eastern edge of the Diablo Platform along the western flank of the Delaware Basin, where one third of the world’s active drilling rigs are working on mostly horizontally drilled unconventional plays. Source/reservoir quality is analyzed by cores, logs and after-frac production tests. Woodford shale here is characterized by low clay, high TOC and porosity and fractured high silica content. Maturation history curves show the oil and wet gas window (Ro – 0.7 to 1.6%) was delayed by Mesozoic uplift until subsequent Laramide and Basin and Range deformation. Similar tectonic histories exist from southern New Mexico to Big Bend, Texas. Thermal evolution can be evaluated for individual areas. Geologic and economic parameters for the Alpine High may exceed well-known successes of the Oklahoma Woodford, Pennsylvania Marcellus Shale and south Texas Eagle Ford plays. This structurally high area was highlighted in articles in the West Texas Geological Society guidebooks in 1994 and 1995 for seismic stratigraphy and conventional play potential. A southeast extension of the play concept has been studied by this author for the JM Burguieres Company Hovey Ranches, where previous wells and 3 – D seismic defined a similar multizone oil shale play. An areally large 3 – D seismic survey surrounding the Apache lease block of 182,000 acres is currently underway, and a large leasing effort is going on to the northwest and southeast of the Apache holdings. A vast number of papers have been published on the structural geology of adjacent areas and have an impact on extending this unconventional play concept, dating back to P. B. King’s work on the Glass Mountains and Marathon Uplift in the 1930s. NW-SE- trending structures and faults extend from Big Bend National Park to New Mexico, including the Marathon Uplift. These have Laramide through Basin and Range ages and heating events. Many deep wells were drilled following the large gas discoveries like Gomez Field in the 1960s, but were mostly CO₂ gas. Small oil fields were found on the overthrusted Marathon fold belt in the 1990s. There is plentiful data to document the existence of structures and source rock/unconventional reservoirs; with migration timing to be unraveled.