The Wattenberg Gas Field is a large producing area of natural gas and condensate in the Denver Basin of central Colorado, USA. Discovered in 1970, the field was one of the first places where massive hydraulic fracturing was performed routinely and successfully on thousands of wells. The field now covers more than 2,000 square miles between the cities of Denver and Greeley, and includes more than 23,000 wells producing from a number of Cretaceous formations. The bulk of the field is in Weld County, but it extends into Adams, Boulder, Broomfield, Denver, and Larimer Counties.
Natural gas, also called "Fossil Gas" is a naturally occurring hydrocarbon gas mixture consisting primarily of methane, but commonly including varying amounts of other higher alkanes, and sometimes a small percentage of carbon dioxide, nitrogen, hydrogen sulfide, or helium. It is formed when layers of decomposing plant and animal matter are exposed to intense heat and pressure under the surface of the Earth over millions of years. The energy that the plants originally obtained from the sun is stored in the form of chemical bonds in the gas.
Natural-gas condensate, also called natural gas liquids, is a low-density mixture of hydrocarbon liquids that are present as gaseous components in the raw natural gas produced from many natural gas fields. Some gas species within the raw natural gas will condense to a liquid state if the temperature is reduced to below the hydrocarbon dew point temperature at a set pressure.
The Denver Basin, variously referred to as the Julesburg Basin, Denver-Julesburg Basin, or the D-J Basin, is a geologic structural basin centered in eastern Colorado in the United States, but extending into southeast Wyoming, western Nebraska, and western Kansas. It underlies the Denver-Aurora Metropolitan Area on the eastern side of the Rocky Mountains.
The reservoir rocks are Cretaceous sandstones, shales, and limestones deposited under marine conditions in the Western Interior Seaway.
Sandstone is a clastic sedimentary rock composed mainly of sand-sized mineral particles or rock fragments.
Shale is a fine-grained, clastic sedimentary rock composed of mud that is a mix of flakes of clay minerals and tiny fragments of other minerals, especially quartz and calcite. Shale is characterized by breaks along thin laminae or parallel layering or bedding less than one centimeter in thickness, called fissility. It is the most common sedimentary rock.
Limestone is a carbonate sedimentary rock that is often composed of the skeletal fragments of marine organisms such as coral, foraminifera, and molluscs. Its major materials are the minerals calcite and aragonite, which are different crystal forms of calcium carbonate (CaCO3). A closely related rock is dolomite, which contains a high percentage of the mineral dolomite, CaMg(CO3)2. In fact, in old USGS publications, dolomite was referred to as magnesian limestone, a term now reserved for magnesium-deficient dolomites or magnesium-rich limestones.
The gas and condensate is contained within Cretaceous formations in the deepest part of the Denver Basin, where the rocks were subject to enough heat and pressure to generate oil and gas from organic material in the rock. The field is a stratigraphic trap, basin-centered gas field. Most of the gas-producing formations are considered tight gas, having low natural permeability. Although the field today is in the deepest part of the basin, an unconformity at the base of the Pierre Shale shows that the field is on an early paleohigh active in the Middle Cretaceous.
Tight gas is natural gas produced from reservoir rocks with such low permeability that massive hydraulic fracturing is necessary to produce the well at economic rates. Tight gas reservoirs are generally defined as having less than 0.1 millidarcy (mD) matrix permeability and less than ten percent matrix porosity. Although shales have low permeability and low effective porosity, shale gas is usually considered separate from tight gas, which is contained most commonly in sandstone, but sometimes in limestone. Tight gas is considered an unconventional source of natural gas.
The Pierre Shale is a geologic formation or series in the Upper Cretaceous which occurs east of the Rocky Mountains in the Great Plains, from Pembina Valley in Canada to New Mexico.
Although numerous wells had drilled through the Wattenberg Field over the decades, and many drillers and wellsite geologists noticed gas “shows” (indications) in the "J" Sandstone and other strata, the "J" Sandstone and other gas-bearing formations had permeability too low to yield gas in commercial quantities. Core samples indicated the "J" Sandstone was similar to the Lower Cretaceous Dakota Sandstone reservoir in the San Juan Basin. This was supported with the Aug. 1967 discovery of the Roundup Field. Additionally, examination of outcrops and electrical logs showed the "J" Sandstone to be a delta-front sandstone.
A core sample is a cylindrical section of (usually) a naturally occurring substance. Most core samples are obtained by drilling with special drills into the substance, for example sediment or rock, with a hollow steel tube called a core drill. The hole made for the core sample is called the "core bowling". A variety of core samplers exist to sample different media under different conditions. More continue to be invented on a regular basis. In the coring process, the sample is pushed more or less intact into the tube. Removed from the tube in the laboratory, it is inspected and analyzed by different techniques and equipment depending on the type of data desired.
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 N-S and 90 miles E-W.
An outcrop or rocky outcrop is a visible exposure of bedrock or ancient superficial deposits on the surface of the Earth.
Amoco geologist Pete Matuszczak noticed that all the wells drilled over a large area recorded noncommercial gas shows, with no water, through the "J" Sandsone (also called the Muddy Sandstone) on the mudlogs, cores, and drillstem tests. He suggested that the area might be made to produce large economic quantities if the wells were treated with the new method of massive hydraulic fracturing, which Amoco was using successfully in the San Juan Basin of New Mexico.
Amoco Corporation, originally Standard Oil Company (Indiana), is a global chemical and oil company that was founded in 1889 around a refinery located in Whiting, Indiana, United States.
Drilling started in 1970, and wells were completed in the J Sandstone, at depths from 7350 to 8500 feet. Drilling deep gas also fortuitously found conventional oil in places in the shallower Terry and Hygiene sandstones.The D Sandstone, another conventional reservoir, also produces in limited areas within Wattenberg.
Additional producing formations were added to the field. Starting in 1981, operators discovered that the Codell Sandstone would yield economic quantities of oil and gas if hydraulically fractured. Hundreds of new wells were drilled and completed in the Codell in the early 1980s; the Codell was often co-completed with the overlying Niobrara Formation. Additional wells were drilled and hydraulically fractured in the Plainview and Lytle formations, below the J Sandstone.
The initial spacing of one "J" Sandstone well per 320 acres was found insufficient to drain the reservoir, so the Colorado Oil and Gas Conservation Commission approved infill wells.
Gas wells in Wattenberg were drilled vertically until 2009, when operators discovered that horizontal wells drilled in the chalk of the Niobrara Formation yielded better quantities of gas and condensate, setting off a new round of drilling.
In 1973, the field was thought to contain 1.1 trillion cubic feet of recoverable gas. Through 2008, the Wattenberg Field had produced 2.8 trillion cubic feet of gas,and an estimated 5.2 trillion cubic feet of recoverable gas remained. In 2013, the US Energy Information Administration listed Wattenberg as the 9th largest gas field in the US in terms of remaining proved gas reserves, 4th in remaining proved oil/condensate reserves. As of March 2018, the field was producing 1.92 billion cubic feet of gas and 331 thousand barrels of oil and condensate per day, from more than 23,000 active wells.
More than 40 companies operate wells in Wattenberg. As of 2017, the five largest producers of oil and gas in the field were: Kerr-McGee, Noble Energy, PDC Energy, Extraction Oil and Gas, and SRC Energy. Together, the top five producing companies produced 84 percent of the total gas produced in 2017.
Coalbed methane, coalbed gas, coal seam gas (CSG), or coal-mine methane (CMM) is a form of natural gas extracted from coal beds. In recent decades it has become an important source of energy in United States, Canada, Australia, and other countries.
Jonah Field is a large natural gas field in the Green River Basin in Sublette County, Wyoming, in the United States. The field is approximately 32 miles (51 km) south of Pinedale and 65 miles (105 km) north of Rock Springs in southwestern Wyoming, and is estimated to contain 10.5 trillion cubic feet (300 km3) of natural gas. Managed by the Bureau of Land Management, the field has a productive area of 21,000 acres (8,500 ha).
The Sirte Basin is a late Mesozoic and Cenozoic triple junction continental rift along northern Africa that was initiated during the late Jurassic Period. It borders a relatively stable Paleozoic craton and cratonic sag basins along its southern margins. The province extends offshore into the Mediterranean Sea, with the northern boundary drawn at the 2,000 meter (m) bathymetric contour. It borders in the north on the Gulf of Sidra and extends south into northern Chad.
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, and southern Saskatchewan, 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 Bakken Formation is a rock unit from the Late Devonian to Early Mississippian age occupying about 200,000 square miles (520,000 km2) of the subsurface of the Williston Basin, underlying parts of Montana, North Dakota, Saskatchewan and Manitoba. The formation was initially described by geologist J.W. Nordquist in 1953. The formation is entirely in the subsurface, and has no surface outcrop. It is named after Henry Bakken, a farmer in Tioga, North Dakota, who owned the land where the formation was initially discovered, during drilling for oil.
The Haynesville Shale is an informal, popular name for a Jurassic Period rock formation that underlies large parts of southwestern Arkansas, northwest Louisiana, and East Texas. It lies at depths of 10,500 to 13,000 feet below the land’s surface. It is part of a large rock formation which is known by geologists as the Haynesville Formation. The Haynesville Shale underlies an area of about 9,000 square miles and averages about 200 to 300 feet thick. The Haynesville Shale is overlain by sandstone of the Cotton Valley Group and underlain by limestone of the Smackover Formation.
The Montney Formation is a stratigraphical unit of Lower Triassic age in the Western Canadian Sedimentary Basin in British Columbia and Alberta.
The Cardium Formation is a stratigraphic unit of Late Cretaceous age in the Western Canada Sedimentary Basin. It takes the name from the fossilized Cockle (Cardiidae) shells that it contains, and it was first described along the Bow River banks by James Hector in 1895. It is present throughout western Alberta and in northeastern British Columbia, and it is a major source of petroleum and natural gas.
The Spraberry Trend is a large oil field in the Permian Basin of West Texas, covering large parts of six counties, and having a total area of approximately 2,500 square miles (6,500 km2). It is named for Abner Spraberry, the Dawson County farmer who owned the land containing the 1943 discovery well. The Spraberry Trend is itself part of a larger oil-producing region known as the Spraberry-Dean Play, within the Midland Basin. Discovery and development of the field began the postwar economic boom in the nearby city of Midland in the early 1950s. The oil in the Spraberry, however, proved difficult to recover. After about three years of enthusiastic drilling, during which most of the initially promising wells showed precipitous and mysterious production declines, the area was dubbed "the world's largest unrecoverable oil reserve."
Shale gas in the United States is rapidly increasing as an available source of natural gas. Led by new applications of hydraulic fracturing technology and horizontal drilling, development of new sources of shale gas has offset declines in production from conventional gas reservoirs, and has led to major increases in reserves of US natural gas. Largely due to shale gas discoveries, estimated reserves of natural gas in the United States in 2008 were 35% higher than in 2006.
The Duvernay Formation is a stratigraphical unit of Frasnian age in the Western Canadian Sedimentary Basin.
Tight oil is light crude oil contained in petroleum-bearing formations of low permeability, often shale or tight sandstone. Economic production from tight oil formations requires the same hydraulic fracturing and often uses the same horizontal well technology used in the production of shale gas. While sometimes called "shale oil", tight oil should not be confused with oil shale, which is shale rich in kerogen, or shale oil, which is oil produced from oil shales. Therefore, the International Energy Agency recommends using the term "light tight oil" for oil produced from shales or other very low permeability formations, while the World Energy Resources 2013 report by the World Energy Council uses the terms "tight oil" and "shale-hosted oil".
As of 2013 the Cline Shale, also referred to as the "Wolfcamp/Cline Shale", the "Lower Wolfcamp Shale", or the "Spraberry-Wolfcamp shale", or even the "Wolfberry", is a promising Pennsylvanian oil play east of Midland, Texas which underlies ten counties: Fisher, Nolan, Sterling, Coke, Glasscock, Tom Green, Howard, Mitchell, Borden and Scurry counties. Exploitation is projected to rely on hydraulic fracturing.
an organic rich shale, with Total Organic Content (TOC) of 1-8%, with silt and sand beds mixed in. It lies in a broad shelf, with minimal relief and has nice light oil of 38-42 gravity with excellent porosity of 6-12% in thickness varying 200 to 550 feet thick.
The Parshall Oil Field is an oil field producing from the Bakken Formation and Three Forks Formation near the town of Parshall, in Mountrail County, North Dakota. The field is in the Williston Basin. The field was discovered in 2006 by EOG Resources, which drilled, and now operates, most of the wells. It was the discovery of the Parshall Field that was largely responsible for the North Dakota oil boom. Parshall’s break-even price is at US$38/barrel, which is the lowest on the Bakken Formation; overall, Bakken’s break-even point is of US$62/barrel.
The Eagle Ford Group is a sedimentary rock formation deposited during the Cenomanian and Turonian ages of the Late Cretaceous over much of the modern-day state of Texas. The Eagle Ford is predominantly composed of organic matter-rich fossiliferous marine shales and marls with interbedded thin limestones. It derives its name from outcrops on the banks of the West Fork of the Trinity River near the old community of Eagle Ford, which is now a neighborhood within the city of Dallas. The Eagle Ford outcrop belt trends from the Oklahoma/Texas border southward to San Antonio, westward to the Rio Grande, Big Bend National Park, and the Quitman Mountains of West Texas. It also occurs in the subsurface of East Texas and South Texas, where it is the source rock for oil found in the Woodbine, Austin Chalk, and the Buda Limestone, and is produced unconventionally in South Texas and the "Eaglebine" play of East Texas. The Eagle Ford was one of the most actively drilled targets for unconventional oil and gas in the United States in 2010, but its output had dropped sharply by 2015. By the summer of 2016, Eagle Ford spending had dropped by two thirds from $30 billion in 2014 to $10 billion, according to an analysis from the research firm, Wood Mackenzie. This strike has been the hardest hit of any oil fields in the world. The spending is, however, expected to increase to $11.6 billion in 2017. A full recovery is not expected any time soon.
Hydraulic fracturing in Canada was first used in Alberta in 1953 to extract hydrocarbons from the giant Pembina oil field, the biggest conventional oil field in Alberta, which would have produced very little oil without fracturing. Since then, over 170,000 oil and gas wells have been fractured in Western Canada. Hydraulic fracturing is a process that stimulates natural gas or oil in wellbores to flow more easily by subjecting hydrocarbon reservoirs to pressure through the injection of fluids or gas at depth causing the rock to fracture or to widen existing cracks. New hydrocarbon production areas have been opened as hydraulic fracturing stimulating techniques are coupled with more recent advances in horizontal drilling. Complex wells that are many hundreds or thousands of metres below ground are extended even further through drilling of horizontal or directional sections. Massive fracturing has been widely used in Alberta since the late 1970s to recover gas from low-permeability sandstones such as the Spirit River Formation. The productivity of wells in the Cardium, Duvernay, and Viking formations in Alberta, Bakken formation in Saskatchewan, Montney and Horn River formations in British Columbia would not be possible without hydraulic fracturing technology. Hydraulic fracturing has revitalized legacy oilfields. "Hydraulic fracturing of horizontal wells in unconventional shale, silt and tight sand reservoirs unlocks gas, oil and liquids production that until recently was not considered possible." Conventional oil production in Canada was on a decrease since about 2004 but this changed with the increased production from these formations using hydraulic fracturing. Hydraulic fracturing is one of the primary technologies employed to extract shale gas or tight gas from unconventional reservoirs.