UGA 50:03 - Lacustrine Source Rocks and Unconventional Oil Resource Plays; A Case Study from the Eocene Green River Formation of the Uinta Basin, Utah

  • David E. Schmude - Axia Energy II LLC
  • Brian R. Berwick - Axia Energy II LLC

DOI: https://doi.org/10.31711/ugap.v50i.107

Abstract

Much information exists on unconventional oil resource plays, their drivers to success and sweet-spot fair- ways. To date, most of the successful oil resource plays are marine Type II kerogen driven systems. Little to  no information is available on successful oil resource plays with lacustrine type I kerogen source rocks and in rock as young as Tertiary age. This paper sets out to define the drivers and provide a case study for such plays  with the Green River oil resource play of Utah’s Uinta Basin as an example. The Green River petroleum sys- tem of the Uinta Basin has generated vast amounts of hydrocarbons, in the form of gilsonite (~10 billion barrels), tar sands (~12 billion barrels), and oil (>700 million barrels) (Johnson, 2016; Schamel, 2015). In addition, the USGS estimates an additional 1.32 trillion barrels of in-place resource in the oil shales of the Green  River Formation. Lacustrine source rocks and their type I kerogen follow a different generative path to immiscible oil generation than the more common marine derived type II kerogens. The oil generative capacity of this  lacustrine source is much greater than that of type II kerogen and is characterized by a distinctive highly paraffinic crude oil. These unique aspects provide exceptionally elevated formation pressures within the source rock  in the oil generative window, setting it apart from other unconventional oil resource plays. As in all unconventional oil resource plays, identification and mapping of the best source rock is key to defining sweet-spots  within the play. With an understanding of source rock distribution and thermal maturity, the extents of the play  and resource in-place can be defined aerially for the numerous productive intervals of the Green River Formation. Finally, we will address the key attributes of this petroleum system such that it may be used as a model  for other possible lacustrine sourced unconventional oil resource plays.