Devonian Shale Oil Production in the Burning Springs Anticline, West Virginia
Devonian aged shales produce gas throughout most of southwestern West Virginia, eastern Kentucky and southeast Ohio. The vast majority of wells produce only natural gas with no associated liquids. There are a few areas where significant volumes of liquids (>20,000 BO per well) have been produced and nearly all of those are located either on, or adjacent to, the Burning Springs Anticline. The Burning Springs Anticline is an unusual north to south trending fold which is approximately 40 miles long and 3 to 5 miles wide. The flanks of the anticline dip steeply to the east and west. The formation of the anticline has been studied by many geologists over the years and is thought to be the result of the western terminus of a thrust sheet whose decollement is the Silurian Salina salt. The anticline was formed during the Alleghenian Orogeny by thrusting along reactivated basement faults. The productive shales have been highly fractured by these tectonic features, which have increased the porosity and permeability of the formation. The Devonian Shale is composed of the Upper Devonian undivided, Lower Huron, Java, Rhinestreet and Marcellus shales. The upper Devonian undivided and the Lower Huron shales contain numerous thin bedded siltstones in the shale which are easily fractured. The oil in the Burning Springs area is produced from intervals in these two shales. These shales can be over 2,400 ft. thick in the area. The Burning Springs drilling boom began in 1980 with the drilling by PDC Energy of a high-volume well in Ritchie County, WV that flowed condensate at rates in excess of 1,000 BOPD. Over the next several years more than 5,000 wells were drilled in pursuit of similar high-volume wells in the areas either on or to adjacent to the anticline. All of the liquids produced were high API gravity condensates. A Berea structure map with cumulative oil production bubbles shows that the best areas for oil production are along the crest of the anticline and near strike-slip faults. The Grow area lies along the crest of the southern terminus of the anticline and has 26 wells that have produced 598,362 BO. The wells’ average production is 88,123 Mcf and 23,934 BO. The Mellin Ridge area is near a strike-slip fault and the area contains 19 wells that have produced 530,615 BO and the wells’ average production is 115,101 Mcf and 27,941 BO. The wells in both areas were drilled with air, their rock pressure is below normal and the wells were fracked with nitrogen or foam. There are many areas in the Burning Springs Anticline and near the strike-slip faults that can be developed in the Devonian Shale for oil and gas. There has been much research done on shale reservoir characterization during the past 15 years. New wells drilled in the Burning Springs area should have petrophysical analyses performed to identify the best intervals for oil and gas production. This information will help the operator decide whether to drill vertical or horizontal wells.
AAPG Datapages/Search and Discovery Article #90373 © 2019 AAPG Eastern Section Meeting, Energy from the Heartland, Columbus, Ohio, October 12-16, 2019