The Greater Green River Basin (GGRB) is a 21,000 square mile basin located in Southwestern Wyoming. The Basin was formed during the Cretaceous period sourced by underlying Permian and Cretaceous deposits. The GGRB is host to many anticlines created during the Laramide Orogeny trapping many of its hydrocarbon resources. It is bounded by the Rawlins Uplift, Uinta Mountains, Sevier overthrust belt, Sierra Madre Mountains, and the Wind River Mountain Range. [1] The Greater Green River Basin is subdivided into four smaller basins, the Green River Basin, Great Divide Basin, Washakie Basin, and Sand Wash Basin. Each of these possesses hydrocarbons that have been economically exploited. There are 303 named fields throughout the basin, the majority of which produce natural gas; the largest of these gas fields is the Jonah Field. [1]
The GGRB was formed during the Laramide Orogeny and is split into an east and west region by the Rock Springs Uplift; an intrabasin anticline uplift that consists of units formed at the end of the Cretaceous into the Eocene. Prior to the basins formation in the Cretaceous, many of the basins source rocks come from the Permian Phosphoria Formation. The Phosphoria Formation of Wyoming was deposited in a Successor Basin (a basin that is formed directly after a tectonic event) [2] that lies between the Sevier Orogeny to the west and the ancient Rocky Mountain orogeny to the east. The Phosphoria Sea was a shallow, sediment starved sea that produced lots of carbonates and phosphorus rich sediments that source many of the hydrocarbon reservoirs found in the Rocky Mountain region today. [3] The Laramide Orogeny was not a single event, but a prolonged tectonic event that had different affects across the large Greater Green River basin. Due to the GGRB size each sub-basin has its own unique geologic history and deposition. [4]
The Rock Springs Uplift is a 1,200 square mile asymmetric anticline composed of Late Cretaceous Baxter Shale. This anticlinal uplift separates the Green River Basin to the West from the Greateat Divide, Washakie, and Sand Wash Basins to the East. The Baxter Shale is extremely eroded forming a deep depression surrounded by sandstone escarpments that are part of the Mesaverde Group. Above the Mesaverde Group escarpments are incised valleys that contain the Lewis Shale, Fox Hills Sandstone, and the Lance Formation. The next unit exposed is the Fort Union Formation deposited in the Paleocene, followed by lower Eocene Wasatch Formation. Most of these are easily eroded marine shale units deposited from Late Cretaceous into the Early Eocene. [4]
The Green River Basin is the largest sub-basin in the GGRB area at 10,500 square miles. It is defined by multiple outcrops the most prominent being Oyster Ridge, a North to South angled hogback that exposes the Cretaceous Frontier Formation sandstone. The next outcrop is White Mountain containing Mid-Eocene exposure. The North and South margins of the basin are composed of gravels and conglomerates that are Tertiary in age. Eocene deposits dominate the outcrops in the Green River Basin. [4]
The Great Divide Basin is located in the Northeastern part of the GGRB. Earned its name due to its location right on the Continental Divide. The basin is 3,500 square miles with no significant outcropping. It is made up of low hills, dunes, alkali flats, and arid lakes. It is a desert plains environment separated from the Green River Basin by the Rock Springs Uplift to the West. [4]
The Washakie Basin is a 3,000 square mile, rimmed basin in the South central part of the GGRB just below the Great Divide Basin. The rimmed parts of the basin are about 1,000 ft higher than the basin floor and are capped by the Laney Member of the Green River Formation (Mid-Eocene). Below the Laney Member is the exposure of the Wasatch Formation (Lower Eocene). [4]
The Sand Wash is the smallest of the four sub-basins at just 2,000 square miles in size. It is in the Southeastern portion of the GGRB and dips into Northwestern Colorado. There are a few central exposures of Eocene aged rocks that form ridges. The Laney Member of the Green River Formation is exposed along these ridges followed by the Wasatch Formation. Similar to the Washakie Basin just to the North. [4]
There are many source rocks in the GGRB, up to 9 viable units, but the most abundant producers of hydrocarbons are the Permian Phosphoria Formation, the Cretaceous Mowry Shale, and the Cretaceous Mesaverde Group. [1] [5] The Cretaceous source rocks are all marine shales that were deposited in a foreland basin created by the Cretaceous seaway. The marine shales experienced subsidence from the erosion of the Sevier Orogeny as well as Progradational accumulation that topped these anoxic marine shales with clastic alluvium. [1] The clastic alluvium units now serve as a great reservoir rock for the marine shales deposited from the Permian into the Cretaceous. [1]
Phosphoria Formation is made up of Permian Shales. It is believed that the organic rich shales are the primary source to much of the oil in the region. It is thought that the oil from these shales have migrated into the Pennsylvanian Tensleep Formation, and Paleozoic reservoirs of Central and Eastern Wyoming. Due to its carbonate and chert rich depositional environment, the oil found in the Phosphoria Formation as a high sulfur content making it Type-IIS kerogen. This is important to note because sulfur rich oils have been known to mature at much lower temperatures than normal. [6] The Tensleep Formation is the most prominent reservoir rock hosting approximately 142 million barrels of oil with about 12 fields producing from this unit. [7] The Phosphoria Formation was sealed by the marine shale units of the Triassic Dinwoody Formation. This shale seal was broken during the Laramide Orogeny leading to the migration of oil into the Tensleep Formation. The oil now is trapped in anticlines formed by the Laramide. [7]
The Mowry Shale is a well-known source rock of Paleozoic reservoirs in Wyoming with the highest total organic content in the area. [5] It is known to source the Dakota Sandstone and Frontier Formation both prolific reservoirs in the Rocky Mountain Region. [1] The Mowry Shale is oil prone for the most part due to the collection of Type-II kerogen at deposition. [6] The Mowry is unique because it is sealed by marine shales and trapped by both anticlines and faults. [7] The Mowry Shales are estimated to hold 6.6 million barrels of oil and about 2 billion cubic feet of gas. [7]
The Cretaceous Mesaverde Group supplies much of the gas to GGRB. The Mesaverde Group was a product of two major transgressions and regressions that lasted approximately 6 million years followed by another sequence that lasted 3 million years. Though much of the Mesaverde units were eroded and this is observed by the unconformity that splits the lower Mesaverde Group from the Upper. [8] The Mesaverde Group is dominated by Type-III Kerogen making it a great source for gas and a decent source for oil. [6] The Mesaverde Group is predominately sealed by marine shales that overlie the group. The Mesaverde Group experiences anticline traps, fault traps, and stratigraphic pinch-out traps in the fields it functions as source rock for throughout the GGRB. [9] The Mesaverde has an estimated production level of 2.3 million barrels of oil, and about 25.83 trillion cubic feet of gas making the Mesaverde Group the ideal source for gas exploration. [9]
The geology of the Grand Teton area consists of some of the oldest rocks and one of the youngest mountain ranges in North America. The Teton Range, partly located in Grand Teton National Park, started to grow some 9 million years ago. An older feature, Jackson Hole, is a basin that sits aside the range.
The San Juan Basin is a geologic structural basin located near the Four Corners region of the Southwestern United States. The basin covers 7,500 square miles and resides in northwestern New Mexico, southwestern Colorado, and parts of Utah and Arizona. Specifically, the basin occupies space in the San Juan, Rio Arriba, Sandoval, and McKinley counties in New Mexico, and La Plata and Archuleta counties in Colorado. The basin extends roughly 100 miles (160 km) N-S and 90 miles (140 km) E-W.
The Uinta Basin is a physiographic section of the larger Colorado Plateaus province, which in turn is part of the larger Intermontane Plateaus physiographic division. It is also a geologic structural basin in eastern Utah, east of the Wasatch Mountains and south of the Uinta Mountains. The Uinta Basin is fed by creeks and rivers flowing south from the Uinta Mountains. Many of the principal rivers flow into the Duchesne River which feeds the Green River—a tributary of the Colorado River. The Uinta Mountains form the northern border of the Uinta Basin. They contain the highest point in Utah, Kings Peak, with a summit 13,528 feet above sea level. The climate of the Uinta Basin is semi-arid, with occasionally severe winter cold.
The Piceance Basin is a geologic structural basin in northwestern Colorado, in the United States. It includes geologic formations from Cambrian to Holocene in age, but the thickest section is made up of rocks from the Cretaceous Period. The basin contains reserves of coal, natural gas, and oil shale. The name likely derives from the Shoshoni word /piasonittsi/ meaning “tall grass”.
The Williston Basin is a large intracratonic sedimentary basin in eastern Montana, western North Dakota, South Dakota, southern Saskatchewan, and south-western Manitoba that is known for its rich deposits of petroleum and potash. The basin is a geologic structural basin but not a topographic depression; it is transected by the Missouri River. The oval-shaped depression extends approximately 475 miles (764 km) north-south and 300 miles (480 km) east-west.
The Wind River Basin or Shoshone Basin is a semi-arid intermontane foreland basin in central Wyoming, United States. It is bounded by Laramide uplifts on all sides. On the west is the Wind River Range and on the North are the Absaroka Range and the Owl Creek Mountains. The Casper Arch separates the Wind River from the Powder River Basin to the east and the Sweetwater Uplift lies to the south. The basin contains a sequence of 10,000–12,000 feet of predominantly marine sediments deposited during the Paleozoic and Mesozoic Eras. During the Laramide over 18,000 feet of Eocene lacustrine and fluvial sediments were deposited within the basin. Following the Eocene an additional 3,000 feet of sediments were deposited before, and as the basin was uplifted in the late Tertiary.
Safaniya Oil Field, operated and owned by Saudi Aramco, is the largest offshore oil field in the world. It is located about 265 kilometres (165 mi) north of the company headquarters in Dhahran on the coast of the Persian Gulf, Saudi Arabia. Measuring 50 by 15 kilometres, the field has a producing capability of more than 1.2 million barrels per day.
The Mancos Shale or Mancos Group is a Late Cretaceous geologic formation of the Western United States.
The Weald Basin is a major topographic feature of the area that is now southern England and northern France from the Triassic to the Late Cretaceous. Its uplift in the Late Cretaceous marked the formation of the Wealden Anticline. The rock strata contain hydrocarbon deposits which have yielded coal, oil and gas.
The Rock Springs Uplift is an area of uplifted Cretaceous to Eocene rocks in Wyoming surrounded and once covered by sediments of the Green River Formation which were deposited in the Eocene Lake Gosiute. The Rock Springs Uplift formed in the Late Cretaceous through the Eocene and is related to the Laramide orogeny. The structure is a north–south trending anticline with a surface expression of approximately 56 miles (90 km) by 28 mi (45 km). The community of Rock Springs is located on the western margin of the uplift.
The Lewis Shale is a geologic formation in the Western United States. It preserves fossils dating back to the Campanian to Maastrichtian stages of the late Cretaceous period.
The Columbus Basin is a foreland basin located off the south eastern coast of Trinidad within the East Venezuela Basin (EVB). Due to the intensive deformation occurring along the Caribbean and South American plates in this region, the basin has a unique structural and stratigraphic relationship. The Columbus Basin has been a prime area for hydrocarbon exploration and production as its structures, sediments and burial history provide ideal conditions for generation and storage of hydrocarbon reserves. The Columbus Basin serves as a depocenter for the Orinoco River delta, where it is infilled with 15 km of fluvio-deltaic sediment. The area has also been extensively deformed by series of north west to southeast normal faults and northeast to southwest trending anticline structures.
The Bolivar Coastal Fields (BCF), also known as the Bolivar Coastal Complex, is located on the eastern margin of Lake Maracaibo, Venezuela. Bolivar Coastal Field is the largest oil field in South America with its 6,000-7,000 wells and forest of related derricks, stretches thirty-five miles along the north-east coast of Lake Maracaibo. They form the largest oil field outside of the Middle East and contain mostly heavy oil with a gravity less than 22 degrees API. Also known as the Eastern Coast Fields, Bolivar Coastal Oil Field consists of Tía Juana, Lagunillas, Bachaquero, Ceuta, Motatán, Barua and Ambrosio. The Bolivar Coast field lies in the Maracaibo dry forests ecoregion, which has been severely damaged by farming and ranching as well as oil exploitation. The oil field still plays an important role in production from the nation with approximately 2.6 million barrels of oil a day. It is important to note that the oil and gas industry refers to the Bolivar Coastal Complex as a single oilfield, in spite of the fact that the oilfield consists of many sub-fields as stated above.
The geology of Wyoming includes some of the oldest Archean rocks in North America, overlain by thick marine and terrestrial sediments formed during the Paleozoic, Mesozoic and Cenozoic, including oil, gas and coal deposits. Throughout its geologic history, Wyoming has been uplifted several times during the formation of the Rocky Mountains, which produced complicated faulting that traps hydrocarbons.
The geology of Utah, in the western United States, includes rocks formed at the edge of the proto-North American continent during the Precambrian. A shallow marine sedimentary environment covered the region for much of the Paleozoic and Mesozoic, followed by dryland conditions, volcanism, and the formation of the basin and range terrain in the Cenozoic.
The bedrock under the U.S. State of Colorado was assembled from island arcs accreted onto the edge of the ancient Wyoming Craton. The Sonoma orogeny uplifted the ancestral Rocky Mountains in parallel with the diversification of multicellular life. Shallow seas covered the regions, followed by the uplift current Rocky Mountains and intense volcanic activity. Colorado has thick sedimentary sequences with oil, gas and coal deposits, as well as base metals and other minerals.
The geology of North Dakota includes thick sequences oil and coal bearing sedimentary rocks formed in shallow seas in the Paleozoic and Mesozoic, as well as terrestrial deposits from the Cenozoic on top of ancient Precambrian crystalline basement rocks. The state has extensive oil and gas, sand and gravel, coal, groundwater and other natural resources.
The geology of Montana includes thick sequences of Paleozoic, Mesozoic and Cenozoic sedimentary rocks overlying ancient Archean and Proterozoic crystalline basement rock. Eastern Montana has considerable oil and gas resources, while the uplifted Rocky Mountains in the west, which resulted from the Laramide orogeny and other tectonic events have locations with metal ore.
Kapuni is an onshore natural gas-condensate field located in the Taranaki Basin, a ~100,000 km2 partially-inverted rift basin on the Taranaki Peninsula in the North Island, New Zealand. Discovered in 1959 and brought into production in 1970, Kapuni remained New Zealand's only producing gas-condensate field until the offshore Maui gas field began production in 1979.
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