Speaker: Steven Pinta
Topic: Hunton Limestone: A Highly Fractured, Natural Gas-Driven, Multiple Play Carbonate Reservoir Within the STACK Play, Central Oklahoma
Bio: Steven Pinta is Chief Geologist and Exploration Manager – Husky Ventures, Inc.
• 12 Years of Oil and Gas Industry Experience
• 7 years of experience in the Mid-Continent basins including the SCOOP/STACK Plays
• Additional experience in multiple regions and basins across the United States which include the Rocky Mountain regions (DJ, Powder River, Green River, and Paradox Basins), the Appalachian region (Marcellus), the Permian Basin (Midland Basin), and Mid-Continent (STACK/SCOOP, Cherokee Platform) with such notable companies as Schlumberger and Devon
• B.S in Geology and a B.S. in Geophysics from the University of Minnesota and a master’s degree in Geology from the University of Utah.
Abstract: The Hunton Limestone formation lies within the STACK play in central Oklahoma, as well as beyond the defined boundary in north-central and northwest Oklahoma. Structurally, the productive formation lies along the border of the Anadarko basin to the southwest and the Anadarko shelf to the northeast. The Hunton Limestone does not contain primarily conventional porosity as viewed through electric logs from thousands of historic vertical wells. However, this carbonate reservoir, sourced from the overlying Devonian Woodford shale, internally provides multiple characteristics of secondary porosity, such as: diagenesis, karsting, vugular porosity, dolomite, and regional fracturing. From 70+ horizontal wells drilled in central Oklahoma, image log analysis has determined that the entire Hunton interval contains a large network of partial and open fractures that span across the region. These fractures are the primary feature that provides the pooling of hydrocarbons within the reservoir. The Hunton formation is both truncated structurally by the Anadarko shelf and stratigraphically by pinching out to the northeast by the underlying Sylvan Shale. The Hunton formation can be sub-divided into three different producing formation: Upper Hunton (Frisco and Bois d’arc limestones), Middle Hunton, and Lower Hunton (Chimney Hill formation composed of the Clarita and Cochrane limestones).
As a carbonate formation with unconventional porosity, the completion process must also be viewed unconventionally. The fracture network within the formation must be exploited to obtain a long term producing and naturally flowing horizontal well. With a higher than average recovery efficiencies for STACK horizontal wells, EUR’s for the Hunton Limestone intervals range from 125k BO to 385k BO and 2.5 BCFG to 3.5 BCFG. The secondary porosity inherent within the formation, the regional fracture network, and custom fracturing design, ultimately provides evidence for a large and economically viable hydrocarbon reservoir within the STACK play of central Oklahoma.