NEWSLETTER: Wyoming Geological Survey Summer 2019

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Interpreting the past, providing for the future - summer 2019 newsletter

Interactive oil and gas map update reveals new trends in industry

When the Wyoming State Geological Survey (WSGS) set out in 2016 to launch an online, interactive version of the popular Oil and Gas Map of Wyoming, one of the goals that inspired the project was the ability to update the map more frequently to keep up with the state’s rapidly changing oil and gas industry.

The online map is currently updated annually and the most recent update was in May. Each update redefines the spatial extent of oil and gas fields by incorporating new wells drilled in the state during the previous year. In addition to providing up-to-date information, the routine updates allow geologists to see new trends occurring in Wyoming’s oil and gas industry.

Although the 2019 version of the Interactive Oil and Gas Map of Wyoming may not look much different from the outset, a closer look highlights significant activity statewide. Last year, 599 wells were completed in the state. Of these completions, 235 are in the Jonah and Pinedale fields in Sublette County, where operators are testing the field boundaries with nearly 2-mile-long laterals. These two fields produced 38 percent of Wyoming’s 2018 natural gas. 

More than 46 percent of the wells completed in 2018 were horizontal wells, with the majority producing from Upper Cretaceous-age reservoirs in Campbell, Converse, and Laramie counties. The Frontier Formation, Turner Sandstone, and Codell Sandstone continue to be operators’ primary targets in the Powder River and Denver basins. In 2018, the Frontier Formation and the Turner Sandstone accounted for 41 percent of the Powder River Basin and 23 percent of all Wyoming oil production. The Turner Sandstone was also the Powder River Basin’s highest non-coal gas-producing reservoir last year, accounting for 27 percent of all natural gas produced from the basin.

The map contains many layers, including fields, all wells from the Wyoming Oil and Gas Conservation Commission, the subset of wells used to create the fields, bottomhole locations for horizontal and directional wells, in addition to pipelines, surface and mineral management, and base layers including statewide geology.

More information can be found in the news release

WSGS report: significant reserves remain in Gas Hills uranium mining district

Gas Hills uranium mining district

Photo caption: Subtle outcrops of the lower fine-grained member of the early Eocene Wind River Formation near Sarcophagus Butte. View is looking northeast toward the Gas Hills hogbacks. 

The Gas Hills uranium mining district—Wyoming's all-time top-producing district, located in the central part of the state—is the focus of a new WSGS public information circular. The publication is available as a free download.

Uranium is a critical mineral and heavy metal used as a strategic military commodity and for nuclear power generation. The state of Wyoming produces the most uranium and hosts the largest-known uranium reserves in the United States.

Since its discovery in the 1950s, the Gas Hills district has been the top-uranium-producing district in the state. Although production ceased in the 1980s due to a weak market, significant unmined uranium reserves—upwards of 50 million pounds of uranium concentrate—remain in the district.

The new publication addresses geologic factors associated with uranium source rocks, mobilization, mineral precipitation, discovery, mining history, and future uranium-mining potential of the Gas Hills district. 

More information can be found in the news release

Statewide landslide susceptibility study

Landslides happen every year in Wyoming. Most go unnoticed because they occur in unpopulated, remote locations. In an effort to understand where landslides might occur in the future, a new WSGS study focuses on statewide susceptibility of deep-seated landslides, or landslides that involve bedrock.

The results of the investigation are accessible in two ways: a published map, available as a free download or as a hard copy for purchase, and as a new interactive layer on the online Wyoming Geologic Hazards Map.

The goal of the project is to aid in promoting awareness of landslides as a natural geologic hazard and to help focus attention on areas where landslides are not well understood.

“The results of this study are consistent with areas of the state known to have high potential for landslides, including much of northwestern Wyoming, the Wind River Mountains, and the flanks of the Bighorns,” said Seth Wittke, WSGS geologist and map co-author. “However, the results also highlight lesser-known areas of Wyoming that may be at risk for deep-seated landslides. We will focus much of our future work in these areas.”

The map and associated data are meant to be used at regional scales. The study’s results do not incorporate susceptibility to debris flows or other shallow landslides, and are not appropriate for site-specific evaluation.

More information can be found in the news release

Fourth pamphlet added to Wyoming state parks series

Keyhole State Park, Wyoming

Photo caption: Keyhole State Park is the focus of the latest pamphlet in a series about geology in Wyoming state parks.

The WSGS continues adding to its series of information pamphlets about geology in Wyoming’s state parks. The latest publication focuses on Keyhole State Park in the Black Hills region in northeast Wyoming.

The park’s geology preserves the story of Wyoming’s Jurassic and Cretaceous past, a time when much of the state was under water. The pamphlet includes a geologic map and a stratigraphic chart depicting the geologic formations exposed in the park.

There is also an overview of Keyhole Reservoir. The 37,000-acre reservoir on the Belle Fourche River is the largest body of water in the northeast corner of the state.

Available information pamphlets:

Pamphlets in production will cover geology in Bear River, Edness K. Wilkins, Boysen, and Hot Springs state parks. 

Geologic maps of Garden Gulch, Horatio Rock quadrangles now available

Geologists spent summer 2018 mapping the Garden Gulch and Horatio Rock quadrangles in southern Wyoming, resulting in two new 1:24,000-scale bedrock geologic maps:

The projects are continuations of previous mapping work and contribute to the understanding of the state’s complex geology. Written technical reports accompany the maps, and provide additional detail about each quadrangle’s unique geology, structure, and economics as well as geochemical and geochronological analyses.

Both maps are available for a fee at the WSGS office or as a download at no cost on the agency’s website. More about the two maps can be found in the news release, and more about the WSGS mapping program can be found on the agency's website

Director's Corner summer 2019

Summer field work in full swing

Geologists’ favorite time of the year is here—field season. Because our summers are so short in Wyoming, the WSGS is bustling with contractors, field equipment, field vehicles, and an influx of rock samples and new data. The hard work and long days in the field will result in new geologic maps that provide a better understanding of Wyoming’s energy resources and geologic hazards.

Geologic mapping is the first and fundamental step in almost all geologic studies. Geologic maps document rock types, faults, folds, and surficial deposits, which allows us to predict where resources are located, understand how groundwater is situated, identify potential geologic hazards, and reconstruct the geologic history that forms the land we see today. 

Surprisingly, a large portion of the state remains unmapped at a scale appropriate for geologists. Our Geologic Map of Wyoming is at a scale of 1:500,000; this scale provides a useful overview of the state but lacks the detail required to address areas of complex geology.

Maps at a scale of 1:100,000 (30 x 60 minutes) cover a smaller area than the 1:500,000-scale map but show more rock types and geologic structures. Geologic map coverage in Wyoming at this scale is at less than 60 percent for bedrock geology. 

For areas of complicated geology, maps need to be at a scale of 1:24,000 (7.5 minutes) or larger. Although not every area requires a map at this level of detail, currently less than 20 percent of the state is mapped at this scale. 

The WSGS, the U.S. Geological Survey, and several academic institutions continue to work toward better geologic map coverage for Wyoming, but we still have a long way to go. By the end of the summer, geologists at the WSGS will have completed field work to create five new 1:24,000-scale geologic maps: three in the resource-relevant Firehole Canyon area in southwest Wyoming and two in the hazard-prone area around Greys River in northwest Wyoming. These are small steps toward completing geologic map coverage for the state, but we continue to work toward that goal. 

--Dr. Erin Campbell, WSGS Director and State Geologist

Digital depth to Precambrian basement map of WY

The WSGS is creating a basement map that will provide valuable information about the Precambrian geology of Wyoming. The map will serve as the framework for related WSGS projects focused on constraining Precambrian lithology and geochronologic relationships, as well as identify potential areas of economically viable critical mineral deposits.

Critical minerals are important to U.S. national security and the economy. Wyoming hosts significant occurrences of many of these minerals, in part due to the wide variety of geologic environments present throughout the state. Many critical minerals in Wyoming are either found in, or originate from, Precambrian igneous and metamorphic basement rocks. These rocks are exposed at the surface in many of the basement-cored mountain ranges in the state, but can be buried below Phanerozoic strata in nearby basins.

The WSGS is compiling and preserving depth-to-basement and structure data from seismic interpretations, cross sections, and well logs. The data will be incorporated into a Geologic Map Schema-compliant geodatabase and utilized to generate a digital, publicly available depth to the Precambrian basement map.

The project is co-funded through a matching grant to the WSGS by the National Geological and Geophysical Data Preservation Program.

Re-analyzing legacy sediment samples with new technology

This project is focused on re-analyzing legacy sediment samples collected as part of the National Uranium Resource Evaluation in the late 1970s. The goal is to re-analyze the samples using modern analytical methods in search of new areas containing critical and strategic minerals, including uranium, vanadium, titanium, cobalt, and rare earth elements. The new geochemical dataset will contain results for 60 elements with better accuracy than the original data, which only contained analysis for 48 elements.