Timothy R. Klett

Assessment of undiscovered oil and gas in the Arctic.

Arctic Energy Reserves The Arctic consists of approximately equal fractions of terrain above sea level, continental shelves with depths less than 500 meters, and deep ocean basins that have been mostly covered in ice. While the deep ocean regions probably have limited petroleum reserves, the shelf areas are likely to contain abundant ones. Based on the limited amount of exploration data available, Gautier et al. (p. 1175) have constructed a probabilistic, geology-based estimate of how much oil and gas may be found. Approximately 30% of the worlds undiscovered gas, and 13% of its undiscovered oil, may be found north of the Arctic Circle. Advances in the technology of hydrocarbon recovery, as well as vanishing ice cover around the North Pole, make the Arctic an increasingly attractive region for energy source development, although the existing reserves are probably not large enough to shift current production patterns significantly. About 30 percent of the world’s undiscovered gas and 13 percent of the world’s undiscovered oil probably exist north of the Arctic Circle. Among the greatest uncertainties in future energy supply and a subject of considerable environmental concern is the amount of oil and gas yet to be found in the Arctic. By using a probabilistic geology-based methodology, the United States Geological Survey has assessed the area north of the Arctic Circle and concluded that about 30% of the world’s undiscovered gas and 13% of the world’s undiscovered oil may be found there, mostly offshore under less than 500 meters of water. Undiscovered natural gas is three times more abundant than oil in the Arctic and is largely concentrated in Russia. Oil resources, although important to the interests of Arctic countries, are probably not sufficient to substantially shift the current geographic pattern of world oil production.

An evaluation of the U.S. Geological Survey World Petroleum Assessment 2000

This study compares the additions to conventional crude oil and natural gas reserves as reported from January 1996 to December 2003 with the estimated undiscovered and reserve-growth volumes assessed in the U.S. Geological Survey World Petroleum Assessment 2000, which used data current through 1995. Approximately 28% of the estimated additions to oil reserves by reserve growth and approximately 11% of the estimated undiscovered oil volumes were realized in the 8 yr since the assessment (27% of the time frame for the assessment). Slightly more than half of the estimated additions to gas reserves by reserve growth and approximately 10% of the estimated undiscovered gas volumes were realized. Between 1995 and 2003, growth of oil reserves in previously discovered fields exceeded new-field discoveries as a source of global additions to reserves of conventional oil by a ratio of 3:1. The greatest amount of reserve growth for crude oil occurred in the Middle East and North Africa, whereas the greatest contribution from new-field discoveries occurred in sub-Saharan Africa. The greatest amount of reserve growth for natural gas occurred in the Middle East and North Africa, whereas the greatest contribution from new-field discoveries occurred in the Asia Pacific region. On an energy-equivalent basis, volumes of new gas-field discoveries exceeded new oil-field discoveries.

Chapter 43 Assessment of NE Greenland: prototype for development of Circum-Arctic Resource Appraisal methodology

Abstract Geological features of NE Greenland suggest large petroleum potential, as well as high uncertainty and risk. The area was the prototype for development of methodology used in the US Geological Survey (USGS) Circum-Arctic Resource Appraisal (CARA), and was the first area evaluated. In collaboration with the Geological Survey of Denmark and Greenland (GEUS), eight ‘assessment units’ (AU) were defined, six of which were probabilistically assessed. The most prospective areas are offshore in the Danmarkshavn Basin. This study supersedes a previous USGS assessment, from which it differs in several important respects: oil estimates are reduced and natural gas estimates are increased to reflect revised understanding of offshore geology. Despite the reduced estimates, the CARA indicates that NE Greenland may be an important future petroleum province.

Chapter 9: Oil and gas resource potential north of the Arctic Circle

Abstract The US Geological Survey recently assessed the potential for undiscovered conventional petroleum in the Arctic. Using a new map compilation of sedimentary elements, the area north of the Arctic Circle was subdivided into 70 assessment units, 48 of which were quantitatively assessed. The Circum-Arctic Resource Appraisal (CARA) was a geologically based, probabilistic study that relied mainly on burial history analysis and analogue modelling to estimate sizes and numbers of undiscovered oil and gas accumulations. The results of the CARA suggest the Arctic is gas-prone with an estimated 770–2990 trillion cubic feet of undiscovered conventional natural gas, most of which is in Russian territory. On an energy-equivalent basis, the quantity of natural gas is more than three times the quantity of oil and the largest undiscovered gas field is expected to be about 10 times the size of the largest undiscovered oil field. In addition to gas, the gas accumulations may contain an estimated 39 billion barrels of liquids. The South Kara Sea is the most prospective gas assessment unit, but giant gas fields containing more than 6 trillion cubic feet of recoverable gas are possible at a 50% chance in 10 assessment units. Sixty per cent of the estimated undiscovered oil resource is in just six assessment units, of which the Alaska Platform, with 31% of the resource, is the most prospective. Overall, the Arctic is estimated to contain between 44 and 157 billion barrels of recoverable oil. Billion barrel oil fields are possible at a 50% chance in seven assessment units. Undiscovered oil resources could be significant to the Arctic nations, but are probably not sufficient to shift the world oil balance away from the Middle East.

Chapter 19 Geology and petroleum potential of the East Barents Sea Basins and Admiralty Arch

Abstract The US Geological Survey (USGS) recently assessed the potential for undiscovered oil and gas resources of the East Barents Basins and Novaya Zemlya Basins and Admiralty Arch Provinces as part of the USGS Circum-Arctic Resource Appraisal. These two provinces are located NE of Scandinavia and the northwestern Russian Federation, on the Barents Sea Shelf between Novaya Zemlya to the east and the Barents Platform to the west. Three assessment units (AUs) were defined in the East Barents Basins for this study – Kolguyev Terrace Assessment Unit (AU), South Barents Basin and Ludlov Saddle AU, and North Barents Basin AU. A fourth, defined as Novaya Zemlya Basins and Admiralty Arch AU, is coincident with the Novaya Zemlya basins and Admiralty Arch Province. These AUs, all lying north of the Arctic Circle, were assessed for undiscovered, technically recoverable resources resulting in total estimated mean volumes of approximately 7.4 billion barrels of crude oil, 318 trillion cubic feet of natural gas and 1.4 billion barrels of natural gas liquids.

Assessment of undiscovered conventional oil and gas resources in the Wyoming Thrust Belt Province, Wyoming, Idaho, and Utah, 2017

The U.S. Geological Survey (USGS) quantitatively assessed the potential for undiscovered, technically recoverable conventional oil and gas resources in the Wyoming Thrust Belt Province, which is located west of the Southwestern Wyoming Province, east of the Eastern Great Basin Province, south of the Idaho-Snake River Downwarp Province, and north of the Uinta-Piceance Basin Province (fig. 1). The Wyoming Thrust Belt developed by east-directed compression associated with steeply dipping subduction during the Late Jurassic to Late Cretaceous Sevier Orogeny (Lamerson, 1982; Webel, 1987). Compression resulted in a series of stacked thrust sheets that are progressively younger in age to the east. The major thrusts in the Wyoming Thrust Belt Province are the Paris-Willard, Meade, Crawford, Absaroka, Hogsback-Darby, and Prospect (fig. 1). Exploration in the mid-1970s resulted in the discovery of more than 30 oil and gas fields, most of which are associated with the Absaroka thrust sheet. Compared to the Absaroka, exploration along the other thrust sheets has been largely unsuccessful. The temporal sequence of thrust loading and structural deformation has resulted in a complex evolution of petroleum systems in the Wyoming Thrust Belt Province (Warner, 1982; Edman and Surdam, 1984; Burtner and Nigrini, 1994).

Assessment of continuous oil and gas resources of the Timan-Pechora Basin Province, Russia, 2018

The U.S. Geological Survey (USGS) quantitatively assessed the potential for undiscovered, technically recoverable continuous (unconventional) oil and gas resources in the Timan-Pechora Basin Province of Russia (fig. 1). The development of three petroleum systems in the province is related to the tectonic history (Otto and Bailey, 1995; IsmailZadeh and others, 1997; Martirosyan and others, 1998; Lindquist, 1999; Fossum and others, 2001; O’Leary and others, 2004; Sliaupa and others, 2006). The progressive closure of the Uralian Ocean in the Late Permian to Early Jurassic led to the formation of the Ural fold and thrust belt and a west-facing foredeep along the fold belt. As much as 8 kilometers of sediment in the foredeep resulted in the thermal maturation of petroleum source rocks into the gas-generation window and into the oil-maturation window west of the foredeep. Compressional deformation in the Cretaceous effectively ended the maturation process and resulted in erosion of as much as 800 meters. Mild compression in the Oligocene was likely related to the far-field effect of the India-Eurasia plate collision. Uncertainty in this assessment relates to the retention of oil or gas in the reservoirs following compressive deformation and migration.

Assessment of undiscovered oil and gas resources in the Lower Indus Basin, Pakistan, 2017

The U.S. Geological Survey (USGS) completed an assessment of undiscovered, technically recoverable oil and gas resources within the Lower Indus Basin, Pakistan (fig. 1). The Lower Indus Basin is on the Indian-Pakistan plate, and as part of the supercontinent Gondwana during the Permian to Middle Jurassic, it underwent multiple phases of extension culminating in the separation of the Indian-Pakistan plate from Somalia in the Late Jurassic to Early Cretaceous (Robison and others, 1999; Zaigham and Mallick, 2000; Ahmad and others, 2012a). Subsequent separation of the Madagascar and Seychelles blocks from the IndianPakistan plate in the Late Cretaceous to Paleogene led to further extension and the initial formation of conventional structural traps that have been the focus of petroleum exploration (fig. 2) (Naeem and others, 2016). The western margin of the Indian-Pakistan plate was passive from the Early Cretaceous to Eocene, and petroleum source rocks of the Lower Goru and Sembar Formations were deposited along the west-facing passive margin during the Early Cretaceous. Beginning in the Eocene, the IndianPakistan plate collided with Eurasia, which led to the formation of the Kirthar fold belt and the adjacent foreland basin. The Eocene collision also resulted in inversion, uplift, and erosion across the Indus Basin area, but deformation was focused within the fold belt. Geologic Models for Assessment

Assessment of continuous oil and gas resources of the Maracaibo Basin Province of Venezuela and Colombia, 2016

The U.S. Geological Survey (USGS) completed an assessment of undiscovered, technically recoverable continuous oil and gas resources within the Maracaibo Basin Province of Venezuela and Colombia (fig. 1). The Maracaibo Basin Province is a structurally complex region encompassing approximately 58,000 square kilometers between the Sierra de Perijá and Cordillera de Mérida, with the northern boundary generally placed at the Oca-Ancón fault (Mann and others, 2006). More than 30 billion barrels of conventional oil have been produced from the basin, which ranks it as one of the top petroleum-producing basins in the world. Organicrich shales of the Upper Cretaceous La Luna Formation are the main petroleum source rock, and La Luna shales have reached adequate thermal maturity for oil and gas generation throughout much of the basin (Talukdar and others, 1986; Talukdar and Marcano, 1994; Escalona and Mann, 2006). The purposes of this study are (1) to estimate the volumes of recoverable continuous oil and gas remaining in La Luna Formation source rocks following two phases of petroleum generation and expulsion and (2) to postulate the presence of gas resources in low-permeability (tight) sandstones. Although the La Luna Formation is mapped as being partly in the gas generation window, little information is available on potential gas resource distribution and the possible presence of gas resources remaining in the La Luna source rock or in deeply buried, tight sandstones.

Assessment of continuous oil and gas resources in the Pannonian Basin Province, Hungary, 2016

The U.S. Geological Survey (USGS) completed an assessment of undiscovered, technically recoverable continuous oil and gas resources within the Hungarian part of the Pannonian Basin Province (fig. 1). The Neogene Pannonian Basin Province is a structurally complex region surrounded by the eastern Alps, west Carpathians, Munții Apuseni, outer Carpathians, south Carpathians, and Dinaric Alps fold belts (Royden, 1988; Dolton, 2006; Tari and Horváth, 2006; Matenco and Radivojević, 2012). Badics and Veto (2012) summarized all of the pertinent geologic and geochemical data on potential continuous (shale oil and shale gas) reservoirs in the Hungarian part of the Pannonian Basin Province. Badics and Veto (2012) concluded that the most viable continuous reservoirs are within the Triassic Kossen Shale, the Lower Jurassic Mecsek Unit, and the lower Oligocene Tard Shale. The purpose of this study is to estimate potential volumes of recoverable continuous oil and gas resources within these three stratigraphic intervals.