People often associate Utah with spectacular canyons cut into the Colorado Plateau, the state’s five national parks, incredible skiing in the beautiful mountains, the opportunity to wade around in the briny water of Great Salt Lake or hearing the Mormon Tabernacle Choir sing the “Hallelujah Chorus.” Visitors to the state, as well as most of its citizens, don’t think of Utah as a major producer of oil and gas.
However, Utah has consistently ranked 15th in gas production in the United States, having produced more than 14 trillion cubic feet. Utah generally ranks around 12th in oil production, having produced almost 1.8 billion barrels. Utah has about 14,000 active wells and more than 200 fields have been discovered, ranging from small fields consisting of a single well to fields with hundreds of wells that have produced millions of barrels of oil or trillions of cubic feet of gas.
There are four major producing regions in Utah: the Uinta Basin in eastern Utah, the Paradox Basin in southeastern Utah, the Ferron gas plays in central Utah and the thrust belt, as well as scattered small fields and larger “one-field wonders.”
Why is Utah a major hydrocarbon producer?
Basically, it has “the right stuff” – the right geologic history. The ages of the rocks exposed in Utah include every geologic eon, era, period and epoch. Three geologic provinces come together in Utah: the Colorado Plateau, Middle Rocky Mountains and Basin and Range. Many of the rocks in these provinces have the qualities necessary to serve as oil and gas reservoirs, sources or seals, combined with depositional and structural events to create the major hydrocarbon-producing regions in Utah.
Utah’s oil and gas exploration history extends back almost 130 years. Like their colleagues elsewhere, early wildcatters took great risks and drilled wells in some of the most remote and unusual places in the United States. The geologic knowledge gained from these exploration efforts helped to piece together Utah’s geologic history and led the way to the discovery of the large reserves of oil and gas that have made Utah a great producer into the 21st century.
First Drilling and Early Discoveries
In 1891, the Bamberger and Millis No. 1 well in east-central Utah was drilled to a depth of 1,000 feet at a cost of $4,000. Although a dry hole, it was the first well in Utah to specifically target hydrocarbons.
While the well was being drilled, the legendary outlaw Butch Cassidy and his gang, the Wild Bunch, were robbing banks and then hiding out at Robbers Roost 60 miles south of the drill site. That same year, natural gas was accidentally discovered near Farmington Bay on the eastern shore of Great Salt Lake during the drilling of a water well. Named Farmington field, the reservoir consisted of Quaternary lenticular sand and silt beds with gas sourced from marsh and peat deposits. Between 1895 and 1896 before the field was abandoned, an estimated 150,000 MCF of gas from several wells was transported to Salt Lake City in a wooden pipe, marking Utah’s first use of local gas or oil and the beginning of a rich history of exploration.
Wildcats drilled in the early part of the 20th century targeted areas with oil seeps and surface anticlines. Discoveries produced only small, non-commercial amounts of oil and gas. However, they were just the precursors of the major Utah discoveries to follow.
In 1904, oil seeps along the north shore of Great Salt Lake led to the discovery of Rozel Point oil field. In its early history, wells at Rozel Point were drilled “offshore” in the lake. The reservoir was fractured Pliocene basalts within a fault block. The hydrocarbon source was lacustrine strata of the Miocene-Pliocene Salt Lake Group. The oil was extremely heavy, having an API gravity of 5 to 9 degrees with 13-percent sulfur. Well depths reached a maximum of 300 feet. About 2,700 barrels of oil were produced before the field was abandoned.
Oil seeps also led to the 1907 discovery of Virgin Field just to the west of what is now Zion National Park in southwestern Utah near the small town of Virgin. The town was founded in 1858 by Mormon settlers along the Virgin River. A large portion of the local population often came out to watch early drilling operations. The field produced out of fractured carbonates in the Triassic Moenkopi Formation along a structural nose. The field produced a few more than 2,000 barrels of oil before it, too, was abandoned.
In 1908, Mexican Hat Field was discovered based on oil seeps along the San Juan River in southeastern Utah near Monument Valley. The field lies in the shadow of Mexican Hat Rock, an unusual landmark with a capping sombrero-shaped rock measuring 60-by-12 feet and the site of numerous old Westerns and other motion pictures. The reservoir is sandstone in the shallow marine Pennsylvanian Honaker Trail Formation. Wells range in depth from 50 to 500 feet. The field produces to this day with cumulative production of more than 315,000 barrels of oil. It currently produces 2 to 3 barrels per day and produced more than 900 barrels in 2021. Newer wells use PVC pipe for casing and some pump jacks are the size of sewing machines!
Beginning in the 1920s, explorationists began targeting large surface anticlines. Cane Creek oil field was discovered in 1925 in the Paradox fold and fault belt in the northern Paradox Basin. The structure was the large northwest- to southeast-trending, salt-flow-created Cane Creek anticline. A cable-tool rig was floated 20 miles down the Colorado River from the town of Moab, Utah. After encountering oil and gas in the Cane Creek shale of the Paradox Formation, the well blew out, the rig caught fire and was destroyed. Cumulative production was about 1,900 barrels of oil before the field was abandoned. Exploration has continued sporadically for subsidiary structures along the Cane Creek anticline. However, it wasn’t until the 1960s that commercial oil was discovered in a number of fields. In the 1990s, horizontal drilling technology was successfully applied to the Cane Creek shale, and exploration continues to this day. More than 10 million barrels have been produced from the Cane Creek.
In 1927, Clay Basin field was discovered in northeastern-most part of Utah. It was the first commercial gas discovery for the state. Clay Basin is a large surface anticline located just south of the Wyoming border along the northern flank of the eastern Uinta Mountains. Reservoirs include the fluvial Cretaceous Muddy (formerly Dakota) and marine shoreface Frontier Formations. Cumulative production is more than 192 billion cubic feet of gas. The field produced more than 730 million cubic feet of gas in 2021 from the Frontier, whereas the Muddy serves as a gas storage reservoir – the largest facility in the Rocky Mountain region. As a result of the discovery of Clay Basin and new fields found in the Baxter Basin area of southwest Wyoming, gas pipelines were constructed to northern Utah during the late 1920s to early ‘30s. Once through Wyoming, the pipelines had to pass over Utah’s Wasatch Range before ultimately reaching downtown Salt Lake City.
Early Uinta Basin Discoveries
After World War II, the industry turned its attention to eastern Utah and the Uinta Basin area. In 1948, Ashley Valley field was discovered along the southern flank of the eastern Uinta Mountains. It was Utah’s first commercial oil discovery. The trap is a subtle anticline with fault closure defined by surface mapping and drilling. The primary reservoir is the eolian Pennsylvanian-Permian Weber Sandstone containing oil sourced from both the Permian Phosphoria Formation and Cretaceous Mancos Shale. The Weber and the entire stratigraphic section to the surface are exposed a mere 10 miles from the field. After more than 70 years, Ashley Valley field has produced over 21 million barrels of oil and still produces to this day.
Although no fields like Ashley Valley have been found in Utah since, major discoveries not long after the discovery of Ashley Valley opened the Uinta Basin just to the south and southwest where most of the drilling activities continue today. The primary oil-producing reservoir in the basin is the Green River Formation, which was deposited in ancient Lake Uinta during the Eocene. Roosevelt (now Bluebell) and Redwash fields were discovered in 1949 and 1951, respectively. Later production was discovered in the alluvial/fluvial Paleocene-Eocene Wasatch Formation. The traps are anticlines (structural noses) combined with stratigraphic pinchouts of alluvial and marginal lacustrine sandstone beds into offshore marlstone and kerogen-rich shale, the source of the hydrocarbons.
In 1952, Utah’s largest gas field, Natural Buttes, was discovered in the eastern Uinta Basin, where the basin tends to be more gas prone. The major reservoirs in the eastern Uinta Basin fields consist of the Late Cretaceous Mesaverde Group and the Wasatch Formation. Fluvial sandstones of the Mesaverde were derived from the Sevier Highlands to the west, and wave-dominated deltaic sandstones were deposited along the Interior Seaway. Alluvial and fluvial deposits of the Wasatch were associated with the early stages of Lake Uinta. Stratigraphic traps within Natural Buttes and other fields consist of updip pinchouts of fluvial channel, deltaic and shoreface sandstones. Coal in the Mesaverde is the source of the gas. Natural Buttes field has more than 4,800 wells and has produced more than 4 trillion cubic feet of gas. The Uinta Basin fields have produced more than 830 million barrels of oil and 7 trillion cubic feet of gas.
Early Paradox Basin Discoveries
In the late 1940s, new exploration occurred in the Paradox Basin, leading to the first commercial oil discovery there in 1948 – Boundary Butte Field. The trap is a simple surface anticline with tilted oil/water contacts and two reservoirs: the eolian Permian De Chelly Sandstone (oil) and shallow-shelf carbonates of the Pennsylvanian Paradox Formation (gas). The hydrocarbon source is the organic-rich shales of the Paradox Formation. Boundary Butte was particularly significant because the Paradox Formation proved productive for the first time in the southern part of the basin. It led to the discovery of numerous other fields in the region including Greater Aneth – the largest oil field in Utah – in 1956, the same year Elvis came out with “Hound Dog” and the New York Yankees beat the Brooklyn Dodgers in game seven of the World Series. Cumulative production is more than 500 million barrels of oil and nearly 480 billion cubic feet of gas. About 90 fields are in the Utah part of the Paradox Basin, created by stratigraphic traps consisting mainly of algal mounds, oolitic banks and bioclastic shoals. Since the discovery of Boundary Butte, total Paradox Basin production in Utah is more than 610 million barrels of oil and 1.5 trillion cubic feet of gas.
First Cretaceous Conventional Gas and Coalbed Methane Discoveries
The first Cretaceous conventional gas fields in east-central Utah were discovered in the 1950s. During the Late Cretaceous the Interior Seaway covered most of eastern Utah, while the Sevier Highlands continued to rise in the west. Eastward-flowing rivers created large deltaic complexes and coal-forming swamps, including those found in the Ferron Sandstone, a member of the Mancos Shale. Clear Creek field was discovered in 1951 on the Wasatch Plateau. The field is a north-south-trending faulted anticline that produced about 115 billion cubic feet of gas before it was shut in.
In the 1980s, companies began testing the potential for coalbed methane in several of Utah’s large nearby coalfields. In 1992, Drunkards Wash Field was discovered in what is referred to as the Ferron CBM Fairway. It is the second largest gas field in Utah having produced 1.1 trillion cubic feet of gas. Combined, fields in the Ferron Sandstone have produced more than 1.5 trillion cubic feet of gas.
Thrust Belt Discoveries
“I’ll drink all the oil found in…” is a phrase that has sometimes been invoked by geologists and others when discussing regions thought to have no hydrocarbon potential. This was the case for the Utah-Wyoming thrust belt after years of drilling failures. Everything changed with the 1975 discovery of Pineview field in northern Utah, followed by a series of major oil and gas finds in the thrust belt during the late 1970s and early ‘80s. The traps for these fields are ramp anticlines along the leading edge of the Sevier-age Absaroka thrust. The primary reservoir is the eolian Triassic-Jurassic Nugget Sandstone, having hydrocarbons sourced from subthrust Cretaceous marine shale. Cumulative production is more than 33 million barrels of oil and 44 billion cubic feet of gas. Cumulative production from Utah thrust belt fields is more than 170 million barrels of oil and 3.2 trillion cubic feet of gas.
It took longer to extend the producing thrust belt trend into central Utah. After Placid Oil Company drilled 10 dry holes during the late 1970s and early ‘80s in the central Utah thrust belt, its former exploration manager, Doug Sprinkel, proclaimed, “Our drilling program was somewhat successful as we showed others where not to drill!”
A Chevron geologist added that Placid contributed great holes to the advancement of science. The 2004 discovery of Covenant Field (see cover and lead article in the April 2005 issue of the EXPLORER) finally turned the region from one of speculation to proven potential. Ironically, the discovery well was drilled updip to a Chevron dry hole! The trapping mechanism for Covenant is similar to those in northern Utah but with a Carboniferous source. The reservoirs are the Jurassic Navajo and Temple Cap Formations. Covenant has produced essentially no gas but more than 29 million barrels of oil.
Exploration in Great Salt Lake
Perhaps one of the most unusual drilling programs in Utah took place between 1978 and 1980 when Amoco drilled 15 wells “offshore” in Great Salt Lake. The result was the 1979 discovery of the West Rozel heavy oil field in the north arm of the lake. Seismic surveys identified closures in a faulted anticline of a horst and graben system. The reservoir was late Pliocene fractured basalts like those found at the old nearby Rozel Point field. Due to the high sulfur content of the oil and the extremely harsh drilling environment of the highly saline lake water, West Rozel field was abandoned after having produced only 33,028 barrels of oil.
Early Horizontal Drilling Efforts
In 1982, a then-new experimental drilling program was initiated in Grassy Trail Field, a small Moenkopi Formation oil producer in east-central Utah. The new technique was horizontal drilling. Sixty-eight short-radius horizontal laterals (averaging 332 feet in length) were drilled from 18 wells. The program significantly improved production and the ultimate recovery, and it was a precursor to the horizontal drilling that is now the standard practice for wells targeting the Cane Creek shale and the Green River Formation.
This Is The Place
In 1847, Mormon pioneer leader Brigham Young led his followers across the plains to escape religious persecution. As they entered the Salt Lake Valley on July 24, Young proclaimed, “This is the place.”
Not only was it the place for these pioneers to settle, but a place of unparalleled geology and major oil and gas potential beginning with the Bamberger and Millis No. 1 well 44 years later. The exploration efforts, successes, and even the failures of the past provided a great legacy for Utah and laid the groundwork for more unconventional drilling taking place today.