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Production Profiles and Geologic Characteristics of the Niobrara Petroleum System

Abstract

The U.S. Energy Information Administration (EIA) is in the process of updating maps of the major tight oil and shale gas plays of the lower 48 states using publically available geologic data and a commercial well-level database (Drilling Info Inc.). Thematic maps on production trends from the Eagle Ford, Permian, and Bakken plays have recently been published in EIA Today in Energy articles. More complete map series of these plays will be posted to the EIA Maps webpage. For the Niobrara petroleum system, data from 7,359 producing oil and gas wells across Colorado, Wyoming, Montana, Nebraska, Kansas and New Mexico were assessed for geologic properties related to initial production (IP) and daily production volumes during 2013 and 2014. Production profiles, gas-to-oil ratios and recovery volumes vary across ten major Niobrara lithologies stratigraphic units deposited within the Denver-Julesburg, Wind River, Green River, Powder River, Piceance, Sweet Grass Arch, Las Animas Arch, North Park, Raton, Central Mountain Uplift, Williston and San Juan Basins. Niobrara sources rock are classified as dominantly Type II sapropelic and composed of low-permeability chalks, marlstones, shales, and sandstones deposited within the Western Interior Seaway during the Coniacian age of the Late Cretaceous epoch (89 to 86 Ma). Production from the Niobrara formation is primarily characterized by either (1) shallow, biogenic dry gas production, (2) thermogenic gas production within deeper gas-generating windows, or (3) production from a thermogenic oil window. Total organic carbon (TOC) has been observed up to 10% and formation porosity ranges from 8 to 14%. Natural fractures, clay content, comingled siliciclastics, formation depth, and thickness all influence production profiles. Production from the Niobrara formation began in 1901 however legacy oil production has declined over 34 thousand barrels per day and legacy gas production has declined 37 million cubic feet per day since 2007. The use of directional and horizontally drilled wells, multiple wells drilled per pad, and multi-stage hydraulic fracturing well completions are adding over six thousand barrels per day and 51 million cubic feet per day of new oil and gas production from the Niobrara formation since 2007. Additional map layers will be added as additional geologic data, such as porosity, organic content, and thermal maturity, becomes available.