The latest USGS
resource assessment for the Mowry Composite Total Petroleum System, last
assessed in 2005, estimates in-place technically recoverable resources of 473
million barrels of oil (MMBbl) and 27 trillion cubic feet (TCF) of
natural gas.
Interior Secretary Doug
Burgum announced the assessment, part of which is on public lands in
Southwestern Wyoming. He noted that we “map, baby, map” before we
“drill, baby drill.” However, drilling rig counts are down by 34 rigs, or about
6%, from last year at this time. USGS typically focuses its assessments on
undiscovered resources. Thus, this petroleum system. According to World Oil:
“Since exploration began in the 1950s, the Mowry
Composite system, which includes the Dakota Sandstone, the Muddy Sandstone, the
Mowry Shale, and the Frontier Formation, has produced approximately 7.3
trillion cubic feet of natural gas… and 90
million barrels of oil…”
The age of the rocks is Early to Late Cretaceous (Albian to
Coniacian) and the assessment units (AUs) are of several geographically
overlapping units: a Mowry Eastern Conventional Oil and Gas AU, a Mowry Rock
Springs Uplift Conventional Gas AU, a Mowry Moxa Arch Conventional Oil and Gas
AU, a Mowry Moxa Arch Continuous Gas AU, a Mowry Deep Continuous Gas AU, a
Mowry Shale Oil AU, and a Mowry Shale Gas AU. According to the report, the
total organic carbon TOC of the Mowry Shale is significant, which makes it a
good source of rock. However, a clastic source area to the west dilutes the
shale facies as it interbeds with clastic deposits:
“The Mowry Shale is a marine, organic-rich, siliceous
shale that was deposited during the early stages of the second-order Greenhorn
transgressive cycle (Kauffman and Caldwell, 1993). Regional studies indicate
that the Mowry Shale has total organic carbon (TOC) content of as much as 5
weight percent (Burtner and Warner, 1984; French and others, 2022). However,
Mowry Shale facies change westward toward the clastic source area from anoxic,
laminated mudstones into oxic, bioturbated mudstones and sandstones (Burtner
and Warner, 1984). The Mowry Shale is the primary source of oil and gas for the
Mowry Composite TPS, but contributions from the Permian Phosphoria Formation
are possible.”
Most gas production has been
found along the Rock Springs Uplift and the Moxa Arch in Southwestern Wyoming.
The oil assessment units and the gas assessment units of the Mowry Shale are
shown below. Note that areas below 19,000 were exempted from the assessments
since they are too deep to tap with current horizontal drilling
technology.
The reservoirs are typically
overpressured and have porosity values less than 10 percent and permeabilities
less than 0.1 mD. Thus, they are generally “tight rocks.” There are structural
traps associated with uplifts and stratigraphic traps. Natural fractures along
the Moxa Arch have aided production rates in the past.
Below is a type log with
gamma ray (GR) and deep resistivity (ILD) showing the potential reservoirs and
source rocks.
USGS also recently assessed
(2020-2023) the source rock potential of the Mowry and Thermopolis Shales in
the Wind River Basin, Wyoming, just to the northeast of the area assessed here.
USGS assessment tables are
shown below.
References:
Significant
oil and gas resources found in western U.S., says Dept. of Interior. World Oil.
May 21, 2025. Significant
oil and gas resources found in western U.S., says Dept. of Interior
Assessment
of Conventional and Continuous Oil and Gas Resources in the Mowry Composite
Total Petroleum System in the Southwestern Wyoming Province, Wyoming, Colorado,
and Utah, 2024. 2025. Assessment
of Conventional and Continuous Oil and Gas Resources in the Mowry Composite
Total Petroleum System in the Southwestern Wyoming Province, Wyoming, Colorado,
and Utah, 2024
Baker
Hughes Rig Count. Baker Hughes. May 23, 2025. Rig Count Overview & Summary Count
| Baker Hughes Rig Count
New
source rock data for the Mowry and Thermopolis Shales in the Wind River Basin,
Wyoming. USGS. April 24, 2023. New
source rock data for the Mowry and Thermopolis Shales in the Wind River Basin,
Wyoming - ScienceBase-Catalog
No comments:
Post a Comment