PP 1824-T: Geology and Assessment of Undiscovered Oil and Gas

Geology and Assessment of Undiscovered Oil and Gas Resources of the Lena-Anabar Basin Province, 2008

Chapter T of The 2008 Circum-Arctic Resource Appraisal

Professional Paper 1824

U.S. Department of the Interior U.S. Geological Survey Cover. Eocene strata along the north side of Van Keulenfjorden, Svalbard, include basin-floor fan, marine slope, and deltaic to fluvial depositional facies. The age and facies of these strata are similar to Tertiary strata beneath the continental shelves of Arctic Eurasia, thus providing an analog for evaluating elements of those petroleum systems. Relief from sea level to top of upper bluff is approximately 1,500 feet. Photograph by David Houseknecht. Geology and Assessment of Undiscovered Oil and Gas Resources of the Lena-Anabar Basin Province, 2008

By Timothy R. Klett and Janet K. Pitman

Chapter T of The 2008 Circum-Arctic Resource Appraisal Edited by T.E. Moore and D.L. Gautier

Professional Paper 1824

U.S. Department of the Interior U.S. Geological Survey U.S. Department of the Interior RYAN K. ZINKE, Secretary U.S. Geological Survey James F. Reilly II, Director

U.S. Geological Survey, Reston, Virginia: 2018

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Suggested citation: Klett, T.R., and Pitman, J.K., 2018, Geology and assessment of undiscovered oil and gas resources of the Lena-Anabar Basin Province, 2008, chap. T of Moore, T.E., and Gautier, D.L., eds., The 2008 Circum-Arctic Resource Appraisal: U.S. Geological Survey Professional Paper 1824, 19 p., https://doi.org/10.3133/pp1824T.

ISSN 2330-7102 (online) iii

The 2008 Circum-Arctic Resource Appraisal

Chapters

A. Introduction to the 2008 Circum-Arctic Resource Appraisal (CARA) Professional Paper By Donald L. Gautier and Thomas E. Moore

B. Methodology for Assessment of Undiscovered Oil and Gas Resources for the 2008 Circum-Arctic Resource Appraisal By Ronald R. Charpentier

North America

C. Geology and Assessment of Undiscovered Oil and Gas Resources of the Chukchi Borderland Province, 2008 By Kenneth J. Bird and David W. Houseknecht

D. Geology and Assessment of Undiscovered Oil and Gas Resources of the Hope Basin Province, 2008 By Kenneth J. Bird, David W. Houseknecht, and Janet K. Pitman

E. Geology and Assessment of Undiscovered Oil and Gas Resources of the Arctic Alaska Petroleum Province, 2008 By David W. Houseknecht, Kenneth J. Bird, and Christopher P. Garrity

F. Geology and Assessment of Undiscovered Oil and Gas Resources of the Yukon Flats Basin Province, 2008 By Kenneth J. Bird and Richard G. Stanley

G. Geology and Assessment of Undiscovered Oil and Gas Resources of the Northwest Canada Interior Basins Province, Arctic Canada, 2008 By Marilyn E. Tennyson and Janet K. Pitman

H. Geology and Assessment of Undiscovered Oil and Gas Resources of the Franklinian Shelf Province, Arctic Canada and North Greenland, 2008 By Marilyn E. Tennyson and Janet K. Pitman

I. Geology and Assessment of Undiscovered Oil and Gas Resources of the Sverdrup Basin Province, Arctic Canada, 2008 By Marilyn E. Tennyson and Janet K. Pitman

Greenland

J. Geology and Assessment of Undiscovered Oil and Gas Resources of the West Greenland- East Canada Province, 2008 By Christopher J. Schenk iv

K. Geology and Assessment of Undiscovered Oil and Gas Resources of the East Greenland Rift Basins Province, 2008 By Donald L. Gautier

North Atlantic Ocean

L. Geology and Assessment of Undiscovered Oil and Gas Resources of the Jan Mayen Microcontinent Province, 2008 By Thomas E. Moore and Janet K. Pitman

Eurasia

M. Geology and Assessment of Undiscovered Oil and Gas Resources of the Mezen’ Basin Province, 2008 By Timothy R. Klett and Janet K. Pitman

N. Geology and Assessment of Undiscovered Oil and Gas Resources of the Timan-Pechora Basin Province, Russia, 2008 By Christopher J. Schenk

O. Geology and Assessment of Undiscovered Oil and Gas Resources of the East Barents Basins Province and the Novaya Zemlya Basins and Admiralty Arch Province By Timothy R. Klett

P. Geology and Assessment of Undiscovered Oil and Gas Resources of the North Kara Basins and Platforms Province, 2008 By Timothy R. Klett and Janet K. Pitman

Q. Geology and Assessment of Undiscovered Oil and Gas Resources of the Northern West Siberian Mesozoic Composite Total Petroleum System of the West Siberian Basin Province, Russia, 2008 By Christopher J. Schenk

R. Geology and Assessment of Undiscovered Oil and Gas Resources of the Yenisey-Khatanga Basin Province, 2008 By Timothy R. Klett and Janet K. Pitman

S. Geology and Assessment of Undiscovered Oil and Gas Resources of the Northwest Laptev Sea Shelf Province, 2008 By Timothy R. Klett and Janet K. Pitman

T. Geology and Assessment of Undiscovered Oil and Gas Resources of the Lena-Anabar Basin Province, 2008 By Timothy R. Klett and Janet K. Pitman v

U. Geology and Assessment of Undiscovered Oil and Gas Resources of the Tunguska Basin Province, 2008 By Craig J. Wandrey and Timothy R. Klett

V. Geology and Assessment of Undiscovered Oil and Gas Resources of the Lena-Vilyui Basin Province, 2008 By Timothy R. Klett and Janet K. Pitman

W. Geology and Assessment of Undiscovered Oil and Gas Resources of the Laptev Sea Shelf Province, 2008 By Timothy R. Klett and Janet K. Pitman

X. Geology and Assessment of Undiscovered Oil and Gas Resources of the Zyryanka Basin Province, 2008 By Timothy R. Klett and Janet K. Pitman

Y. Geology and Assessment of Undiscovered Oil and Gas Resources of the East Siberian Sea Basin Province, 2008 By Kenneth J. Bird, David W. Houseknecht, and Janet K. Pitman

Z. Geology and Assessment of Undiscovered Oil and Gas Resources of the Vilkitskii Basin Province, 2008 By Kenneth J. Bird, David W. Houseknecht, and Janet K. Pitman

AA. Geology and Assessment of Undiscovered Oil and Gas Resources of the Long Strait Province, Russian High Arctic, 2008 By Kenneth J. Bird, David W. Houseknecht, and Janet K. Pitman

Arctic Ocean

BB. Geology and Assessment of Undiscovered Oil and Gas Resources of the Amerasia Basin Petroleum Province, 2008 By David W. Houseknecht, Kenneth J. Bird, and Christopher P. Garrity

CC. Geology and Assessment of Undiscovered Oil and Gas Resources of the Lomonosov- Makarov Province, Central Arctic Ocean, 2008 By Thomas E. Moore, Kenneth J. Bird, and Janet K. Pitman

DD. Geology and Assessment of Undiscovered Oil and Gas Resources of the Eurasia Basin Province, Eastern Arctic Ocean, 2008 By Thomas E. Moore and Janet K. Pitman vi

Contents

Abstract...... 1 Lena-Anabar Basin Province...... 1 Province Boundary Definition...... 1 Petroleum Occurrence...... 1 Tectonostratigraphic Evolution...... 4 Proterozoic and Early Paleozoic...... 4 Late Paleozoic and Mesozoic...... 7 Petroleum System Elements...... 7 Source Rocks...... 7 Reservoir and Seal Rocks...... 11 Traps and Timing...... 11 Assessment Units...... 11 Lena-Anabar Basin Assessment Unit...... 13 Geological Analysis of Assessment Unit Probability...... 13 Geologic Analogs for Assessment...... 13 Lena-Anabar Basin Updip Assessment Unit...... 14 Geological Analysis of Assessment Unit Probability...... 14 Sukhan-Motorchun Riphean Rift Assessment Unit...... 14 Geological Analysis of Assessment Unit Probability...... 14 Lena-Anabar Basin Province Assessment Results...... 16 Acknowledgments...... 16 References Cited...... 16

Appendixes

[Available for download at https://doi.org/10.3133/pp1824T]

1. Input data for Lena-Anabar Basin Assessment Unit 2. Input data for Lena-Anabar Basin Updip Assessment Unit 3. Input data for Sukhan-Motorchun Riphean Rift Assessment Unit vii

Figures

1. Map of the Lena-Anabar Basin Province and assessment units...... 2 2. Map of the Lena-Anabar Basin Province’s major structural features, approximate depth to economic basement, and location of geologic cross sections and petroleum system models used in the assessment...... 3 3. Regional geologic cross sections in the Lena-Anabar Basin Province...... 4 4. Lithostratigraphic column and total petroleum system events chart for the Lena-Anabar Basin Province...... 6 5. Burial history model for pseudowells in the Lena-Anabar Basin Province assessment units, depicting thermal maturity...... 8

Tables

1. Geologic analogs used in the assessment of the Lena-Anabar Basin Assessment Unit...... 11 2. Field densities, median oil and gas field sizes, and exploration maturities of geologic analogs used in the Lena-Anabar Basin Assessment Unit assessment...... 15 3. Assessment results for the Lena-Anabar Basin Province...... 16

The 2008 Circum-Arctic Resource Appraisal Edited by T.E. Moore and D.L. Gautier U.S. Geological Survey Professional Paper 1824

Chapter T

Geology and Assessment of Undiscovered Oil and Gas Resources of the Lena-Anabar Basin Province, 2008

By Timothy R. Klett and Janet K. Pitman

Abstract and approximate depth to economic basement are shown in figure 2. The U.S. Geological Survey (USGS) assessed the Sedimentary rocks in the geologic province include potential for undiscovered oil and gas resources of the Lena- upper Proterozoic (Riphean and Vendian) carbonate and Anabar Basin Province as part of its Circum-Arctic Resource clastic rocks, Cambrian carbonate rocks with a karstified Appraisal program. The province is in the Russian High Arctic unconformity at the top, and Permian to Cretaceous clastic and is located between the Laptev Sea and the Siberian craton. rocks. Paleozoic (Ordovician through Carboniferous) rocks Three assessment units (AUs) were defined for this study— are absent along the Siberian craton in the southern part of the the Lena-Anabar Basin AU, the Lena-Anabar Basin Updip province because of nondeposition and erosion. To the north, AU, and the Sukhan-Motorchun Riphean Rift AU—and were however, the Paleozoic section becomes more complete and assessed for undiscovered, technically recoverable resources. progressively younger (Shishkin and Isaev, 1999). The estimated mean volumes of undiscovered oil and gas The Lena-Anabar Basin Province is divided into three resources for the Lena-Anabar Basin Province are ~2 billion assessment units (AUs) sufficiently homogeneous in terms of barrels of crude oil, ~2 trillion cubic feet of natural gas, and <1 geology and exploration maturity to be assessed—the Lena- billion barrels of natural gas liquids. All of the undiscovered Anabar Basin, the Lena-Anabar Basin Updip, and the Sukhan- petroleum resources are north of the Arctic Circle. Motorchun Riphean Rift AUs. Only the Lena-Anabar Basin AU was quantitatively assessed.

Lena-Anabar Basin Province Petroleum Occurrence Province Boundary Definition Approximately six exploration wells have been drilled in The boundary of the Lena-Anabar Basin Province is the Lena-Anabar Basin Province. A few wells had natural gas drawn to encompass the Lena-Anabar and Udzhin-Khastahk- shows, but no economic discoveries were made (IHS Energy Motorchun sedimentary basins of the northern Siberian plat- Group, 2007). Extensive degraded petroleum (bitumen) form (fig. 1). This geologic province is flanked by the Anabar deposits are present along the western and northeastern basin Anticlise on the east, the Olenek High and Muna Arch on the margins along the Anabar Anticlise and Olenek High (Ivanov, west, the Olenek fold-and-thrust belt (a Mesozoic compres- 1979). The deposits along the northeastern margin of the prov- sional or transpressional front) on the north, and the limit of ince are volumetrically enormous and potentially recoverable. upper Proterozoic (Riphean) rifts on the south. The province is These continuous (unconventional) accumulations, however, approximately 125,000 km2 in area. Major structural features were not assessed in this study. 2 The 2008 Circum-Arctic Resource Appraisal

100 E 110 E 120 E 130 E

LAPTEV SEA enisey- Khatanga Basin Province

ver Ri Khatanga

r e v i

R Lena-Anabar

r Basin AU

n A Lena-Anabar Basin Province 0 Siberian Craton Province Lena-Anabar Tiksi Updip AU

Olenek River

EPLANATON Sukhan- Motorchun r Lena-Anabar Basin Province e iv R Riphean Rift Assessement units

AU a Other Arctic province n e (except assessed) L Area of Oil or gas field province Gas Oil

Clare 18 Stereographic orth Pole 0 0 100 MLES Stereographic orth Pole 0 0 100 KLMETERS

Figure 1. Map of the Lena-Anabar Basin Province and assessment units (AUs). Oil and gas field data from IHS Energy Group (2007). Geology and Assessment of Undiscovered Oil and Gas Resources of the Lena-Anabar Basin Province, 2008 3

100 E 110 E 120 E 130 E 140 E

LAPTEV Pakhsa SEA Peninsula

y a B Olenek one ga tan Kha Lena-Anabar Basin I' II I

Anabar

Anticlise Udzhin aulacogen III Udzhin High III' Lena-Anabar IV' IV Updip Khastakh aulacogen II' Olenek 0 High

EPLANATON Depth to basement Sukhan- Less than 3 kilometers Motorchun Lena River Muna 3 to 6 kilometers Riphean Rift Arch Greater than 6 kilometers Oilgas field Location of petroleum model Location of cross section Maor fault

Clare 18 Stereographic orth Pole 0 100 200 MLES Stereographic orth Pole 0 100 200 KLMETERS

Figure 2. Map of the Lena-Anabar Basin Province’s major structural features, approximate depth to economic basement, and location of geologic cross sections and petroleum system models used in the assessment. Data from IHS Energy Group (2007) and Persits and Ulmishek (2003). 4 The 2008 Circum-Arctic Resource Appraisal

Tectonostratigraphic Evolution Proterozoic and Early Paleozoic

The Lena-Anabar Basin Province began as a system of Intracratonic extension and rifting occurred during late Proterozoic rifts upon which a carbonate platform and shelf Proterozoic (Riphean) time, along with deposition of carbon- formed. The area was a passive margin until the Cretaceous, ate and clastic sediments. A thick succession of sediments was when it became a foreland basin in front of the Olenek fold- deposited within the grabens (7 to 9 km thick in the Udzhin and-thrust belt. The geologic cross sections in figures A3 and graben between the Anabar Anticlise and Olenek High) B show the character of the basin fill and structure. (Zonenshain and others, 1990). Sediments were thickest along

I I' EST EAST Olenek Bay Anabar River 0 Cretaceous

1 Jurassic

Triassic 2

Pre-Permian Permian Depth, in kilometers 3

4 0 2 0 MLES

0 2 0 KLMETERS

II II'

Lena-Anabar Basin Province EST P-0 EAST Ulakhan-uryakh (Tyumatinskaya; R-0) D’yapal Lena River 0 L. Cretaceous

Jurassic Precambrian-Cambrian Triassic Permian Paleozoic 4 Depth, in kilometers 0 2 0 MLES EPLANATON Fault 0 2 0 KLMETERS Existing well or well field

B EPLANATON Fault

Lena-Anabar Updip Lena-Anabar Basin Existing well or well field Assessment Unit Assessment Unit Udzha Uplift III III' EST hastakh EAST hastakhskaya-930 Charchikskaya-1 aulacogen R-0 (Tyumatinskaya)

Permian-Lower Cretaceous 1

2 Cambrian 3 Vendian 4 Depth, in kilometers 0 MLES Riphean Crystalline basement 6 0 KLMETERS

IV hastakh IV' Udzha Lena-Anabar Updip Lena-Anabar Basin aulacogen EST Uplift Assessment Unit Assessment Unit Burskaya-3410 EAST

0 Permian-Jurassic Reef 1 Cambrian

2 Vendian

Riphean 3

4 Depth, in kilometers 0 MLES Crystalline basement 0 KLMETERS

Figure 3. Regional geologic cross sections in the Lena-Anabar Basin Province. Locations shown on figure 2. Vertical red lines are locations of wells or pseudowells used for petroleum-generation models. Modified from Filipiov and others (1999); Polyakova and others (1986); Shishkin and Isaev (1999); Sokolov (1989); and Surkova (1987).—Continued the passive continental margins of the Siberian craton, but thin open ocean by reefs along the present-day north and northeast elsewhere (Ulmishek, 2001). margins (Gogina and Leonov, 1983; Astashkin and others, Uplift, deformation, and erosion during late Proterozoic 1984; Bakhturov and others, 1990; Ulmishek, 2001). time resulted in an angular unconformity between Riphean Carbonate platform and shelf conditions continued along and overlying Vendian rocks (Zonenshain and others, 1990; the rifted passive margins of the Siberian craton into the early Ulmishek, 2001). Uplift and erosion caused the deposition of Paleozoic. Lower and Middle Cambrian rocks include carbonate rocks and mudstone. Organic-rich (bituminous) mudstone clastic rocks in the lower part of the Vendian section (fig. B4 ). was deposited beyond the reefs in the north and northeast part Rocks in the upper part of the Vendian section include dolos- of the craton during the Lower and Middle Cambrian (fig. B4 ) tone with local beds of anhydrite. Uplift was isolated within (Bakhturov and others, 1990). Permian rocks unconformably the southern part of the Siberian craton, allowing a large, shal- overlie Cambrian rocks in the Lena-Anabar Basin. Paleozoic low lagoon to form during the late Vendian and Early Cam- rocks younger than Cambrian but older than Permian might brian into which evaporites were deposited. The lagoon was exist in the present-day northern part of the basin. The rimmed by carbonate shelves on the present-day southeastern southern part of the province was a positive structural feature and southwestern margins of the craton and separated from the until Permian time. 6 The 2008 Circum-Arctic Resource Appraisal

A Earth system Petroleum system Comments

Sea level curve, in Geologic time scale meters Average global temperature, in degrees Celsius Source rocks raps Age Eon Era Period Epoch Ma

1 20 200 100 0 Rock type Source rock T Reservoir rock Seals Petroleum loss Maturation and migration

M Pleistocene E Gelasian Piacenzian Pliocene anclean Figure 4. Lithostratigraphic column and total petroleum Messinian Tortonian Serravallian Miocene Langhian

eogene system events chart for the Lena-Anabar Basin Province. Burdigalian 20 12. Auitanian Chattian Oligocene Source rocks column shows the percent of the world’s Rupelian Priabonian Cenozoic Bartonian 40 total petroleum reserves generated by source (modified Eocene Lutetian

Paleogene presian from Ulmishek and Klemme, 1990). Average global Thanetian Paleocene Selandian 60 2.8 Danian temperature data is from Frakes and others (1992) and Maastrichtian Barrett (2003). Sea level curve is from Golonka and Campanian 80 Late Santonian Kiessling (2002) and Hardenbol and others (1998). Geologic Coniacian Turonian Cenomanian time scale is that of Gradstein and others (2004). Data from 100 29.0 Albian Filipiov and others (1999); Grausman (1996); Kontorovich Cretaceous

Aptian 120 and others (1994); Lebchuk (1990); Shenfil’ (1991); Shishkin Early Barremian and Isaev (1999); and Surkova (1987). 2.6 Hauterivian Valanginian 140 Berriasian anovstanskaya Tithonian Mesozoic Late Kimmeridgian 2.0 Sigovskaya Oxfordian 160 Tochinskaya Callovian Bathonian uryung- Middle Bajocian Tumus Aalenian Arangostakh Jurassic Saybulakh Toarcian 180 Saybulak Airkat

Pliensbachian Airkat Early Sinemurian Hettangian imnyaya 200 Rhaetian

orian 1.2 Late 220 Carnian riassic T Ladinian Middle Anisian 240

Early Olenekian Induan Changhsingian Lopingian Wuchiapingian Phanerozoic 260 Capitanian Guadalupian Wordian Roadian Kungurian

Permian Artinskian 280 Cisuralian Sakmarian

8.0 Asselian 300 Gzhelian Late Kasimovian Middle Moscovian Early Bashkirian Pennsylvanian Coal-bearing 320 Late Serpukhovian 0.4 Carboniferous Middle Visean 340 EPLANATON

Mississippian Rock type Tournaisian Early Continental clastic rocks 360 earshore clastic rocks 8.0 Famennian Late Offshore clastic rocks

Frasnian 380 Organic-rich mudstone

Givetian Volcanic and volcaniclastic

Devonian Middle Eifelian rocks 0.3 400 Paleozoic Emsian Carbonate rocks Early Pragian Lochkovian Petroleum system Pridoli 420 Ludlow Ludfordian Gorstian Identified presence Wenlock Homerian 9.0 Sheinwoodian Telychian Possible presence Silurian Llandovery Aeronian 440 Ocean anoxic event Rhuddanian Hirnantian

Upper

460 Darriwilian Middle Ordovician

Lower 480 Tremadocian

1.0 Furongian Paibian 00

Middle

20 Cambrian

Lower

0.2 Ediacaran

Proterozoic 80 Neoproterozoic Snowball Earth Vendian Riphean Geology and Assessment of Undiscovered Oil and Gas Resources of the Lena-Anabar Basin Province, 2008 7

Lena-Anabar Basin Lena-Anabar Basin Updip Petroleum System Elements Kessyusa and Erkeket RTEST SUTEAST Fms., 120 m 0 0 B Cretaceous Cambrian Several total petroleum systems could exist in the Lena- Anabar Basin Province; possible source rocks include Pro- Khatyspyt and Turkut terozoic, Cambrian, Permian, and Triassic strata. Because of Fms., 360 m Vendian Jurassic 0. Maastakh Fm., m suspected mixing of petroleum, however, only one potential up to .0 m eroded system was identified: the Proterozoic-Paleozoic-Mesozoic composite total petroleum system (TPS). A lithostratigraphic 1.0 Khaipakh Fm., 630 m riassic T Permian- column and total petroleum system events chart showing 1.0 petroleum system elements are depicted in figure A4 , and detailed stratigraphy is shown in figure B4 .

Debengde Fm., 30 m

Permian 1. Source Rocks

2.0 Riphean

Sukhansk Fm. Solooli Group Lopar Fm. Arymas Fm., 280 m Oil stained The most likely petroleum source rocks in the Lena-Ana- 2.0 Approximate thickness, in kilometers bar Basin Province are Proterozoic and Cambrian mudstone. Kyutingde Fm., 230 m Proterozoic source rocks include organic-rich, in some places Charchik Sygynakhtakh Fm., Fm. Tyuessalin Cambrian 200 m bituminous, carbonate rocks and mudstone of the Riphean Approximate depth, in kilometers Fm. 3.0 Crystalline Basement Olenek or unkyulyabit- 2. Khaipakh Formation and the Vendian Khatyspyt Formation uryakh Fm. Bur Fm. Kuonam Fm. Erkeket Fm. (fig. 4B) associated with Proterozoic rift/sag areas (Shenfil’, (Emyaksin) oui Fm. KhastakhKessyusa Fm. 1991; Shishkin and Isaev, 1999). Cambrian source rocks stud- Turkut Fm. ied in outcrop and cores include the Chaburskaya Formation Khatyspyt Fm.

endian and the bituminous Kuonam Formation mudstone and carbon- V Maastakh Fm. 4.0 Khaipakh Fm. ate rocks, which probably did not generate petroleum in the shallower parts of the basin where they were studied (Ivanov,

Riphean 1979; Bakhturov, 1985; Bakhturov and others, 1990), though they could be thermally mature for petroleum generation in deeper parts of the basin (figs. A3 and B). Figure 4.—Continued Petroleum-generation models indicate that Proterozoic and Cambrian source rocks would have generated oil and natural gas in the deeper northern part of the province. These source rocks entered the oil window by the end of the Cam- brian (fig. A5 ). If there was no deposition during the Paleo- Late Paleozoic and Mesozoic zoic, crude oil might have been trapped and preserved until the present; otherwise, substantial burial would have cracked The Siberian craton drifted northward from the Devonian crude oil into natural gas and possibly dispersed it by subse- to the Triassic, moving from a warm, dry climate at low to quent uplift and erosion (fig. B5 ). middle latitudes into a cooler humid climate at higher latitudes Permian continental to marine rocks might be another (Zonenshain and others, 1990). The margins of the craton source of petroleum. The clastic rocks are carbonaceous, remained passive during the late Paleozoic and into the early contain ~2 percent total organic carbon (as terrestrial organic Mesozoic, but thick successions of deltaic, paralic, nearshore material), and are presumed to be one of the sources of petro- marine, and submarine fan strata were deposited in the Lena- Anabar Basin (fig. A3 ). During the Permian and Cretaceous, leum in the Khatanga Saddle, which is located northwest of >4 km of clastic continental and shallow marine sediment was Lena-Anabar Basin Province (Ivanov, 1979; Polyakova and deposited (Polyakova and others, 1986). others, 1984, 1986). Permian source rocks entered the oil- The Olenek fold-and-thrust belt is a Cretaceous generation window during the Mesozoic in deeper parts of the deformation front that bounds the northern margin of the basin, in the northern part of the province, and are presently in Lena-Anabar Basin. During the deformation, an asymmetric the oil-generation window, according to petroleum-generation foreland basin developed along the distal part of the Lena- models (fig. C5 ). Triassic and Upper Jurassic (Tithonian) Anabar Basin passive margin. Cenozoic rocks are absent in mudstones are organic rich, but these rocks are most likely the area. immature in most of the basin. 8 The 2008 Circum-Arctic Resource Appraisal

Age, in millions of years before present 800 700 600 00 400 300 200 100 0 Palaeozoic Mesozoic Cenoz. 0 Cam. Ordv. Sil. Dev. Carb. Pm. Tr. Jur. Crt. Pg. Middle Jurassic Reservoir 1,000 Permian

2,000 Source and Cambrian reservoir 3,000 Vendian 4,000

Source ,000 EPLANATON Riphean mmature (less than 0.6 Ro)

Burial depth, in meters 6,000 Oil one (0.61.3% Ro) Gas one (1.32.0% R ) 7,000 o Overmature (greater than 2.0 Ro) Triassic 8,000 magmatic Foreland Passive margin activity basin 9,000

Age, in millions of years before present Temperature, in 800 600 400 200 0 degrees Celsius Easy Ro, in percent Palaeozoic Mesozoic Cen. 0 0 100 0.10 1.00 10.00 Cam. O S D Carb. P Tr. Jur. Crt. Pg. 0 200 Paleo-water depth Middle Jurassic 1,000 Permian 0 Meters 2,000 200 Cambrian 40 Oil Gas Sediment-water interface temperature Immature Overmature 3,000

20 Vendian

4,000 Burial depth, in meters Degrees Celsius 0 Riphean 100 Heat flow Triassic ,000 magmatic activity 0 Foreland 6,000

Milliwatts per suare meter basin Passive margin 0

Figure 5. Burial history model for pseudowells in the Lena-Anabar Basin Province assessment units (AUs), depicting thermal maturity. Locations of wells shown in figure 2. A, Petroleum system model for Lena-Anabar Basin AU northern pseudowell (shown in figure 3A) under scenario 1, the base case, in which there is nondeposition of a middle and late Paleozoic section, followed by deposition, petroleum generation, and accumulation during the Permian and Mesozoic. B, Petroleum system model for Lena-Anabar Basin AU northern pseudowell (shown in figure 3A) under scenario 2, the worst case, in which there is deposition of a middle and upper Paleozoic section with petroleum generation and accumulation, followed by middle to late Paleozoic erosion. C, Petroleum system model for Lena-Anabar Basin AU for southern pseudowell (shown in figure 3B). Ro, vitrinite reflectance, in percent (%). Data from Duchkov and others (1982); Polyakova and others (1986); and Shishkin and Isaev (1999). Petromod references: Integrated Exploration Systems (2008); Sweeney and Burnham (1990); and Wygrala (1989). Geology and Assessment of Undiscovered Oil and Gas Resources of the Lena-Anabar Basin Province, 2008 9

B Age, in millions of years before present

800 700 600 00 400 300 200 100 0 Palaeozoic Mesozoic Cenoz. Cambrian Ordv. Sil. Dev. Carb. Pm. Tr. Jur. Crt. Pg. 0 EPLANATON Permian mmature (less than 0.6 R ) Middle Reservoir 1,000 o Jurassic Oil one (0.61.3% Ro) Gas one (1.32.0% R ) 2,000 o Overmature (greater Source and Cambrian reservoir than 2.0 Ro) 3,000 Vendian 4,000

Source ,000 Riphean

Burial depth, in meters 6,000

7,000 Triassic magmatic 8,000 activity Foreland Passive margin basin 9,000

Age, in millions of years before present Temperature, in degrees Celsius Easy R , in percent 800 600 400 200 0 o 0 0 100 0.10 1.00 10.00 Palaeozoic Mesozoic Ce. 0 Cam. O S D Carb. P T Jur. Crt. Pg. 200 Paleo-water Depth Middle Jurassic 1,000 Permian 0 Meters

2,000 200 40 Sediment-water interface temperature Cambrian Oil Gas Over- Immature mature 3,000 20 Vendian Degrees Celsius 0 Burial depth, in meters 4,000 100 Heat flow Triassic magmatic Riphean 0 activity ,000 Foreland

Milliwatts per suare meter basin 0 Passive margin 6,000

Figure 5. Burial history model for pseudowells in the Lena-Anabar Basin Province assessment units (AUs), depicting thermal maturity. Locations of wells shown in figure 2. A, Petroleum system model for Lena-Anabar Basin AU northern pseudowell (shown in figure 3A) under scenario 1, the base case, in which there is nondeposition of a middle and late Paleozoic section, followed by deposition, petroleum generation, and accumulation during the Permian and Mesozoic. B, Petroleum system model for Lena-Anabar Basin AU northern pseudowell (shown in figure 3A) under scenario 2, the worst case, in which there is deposition of a middle and upper Paleozoic section with petroleum generation and accumulation, followed by middle to late Paleozoic erosion. C, Petroleum system model for Lena-Anabar Basin AU for southern pseudowell (shown in figure 3B). Ro, vitrinite reflectance, in percent (%). Data from Duchkov and others (1982); Polyakova and others (1986); and Shishkin and Isaev (1999). Petromod references: Integrated Exploration Systems (2008); Sweeney and Burnham (1990); and Wygrala (1989).—Continued 10 The 2008 Circum-Arctic Resource Appraisal

Age, in millions of years 00 400 300 200 100 0 Palaeozoic Mesozoic Cenozoic Ordovician Sil. Dev. Carboniferous Perm. Tri. Jurassic Cretaceous Pg. g. 0

Cretaceous Reservoir 1,000

Jurassic

2,000 Reservoir Triassic

3,000 Source

Burial depth, in meters Triassic Permian magmatic 4,000 EPLANATON activity mmature (less than 0.6 Ro) Cambrian Oil one (0.6 - 1.3% Ro) Foreland Source ,000 Passive margin basin ,400

Age, in millions of years before present Temperature, in Easy Ro, in percent 00 400 300 200 100 0 degrees Celsius Palaeozoic Mesozoic Cenoz. 0 0 100 0.10 1.00 10.00 Ordo. S Dev. Carb. P Tri. Jur. Crt. Pg. 200 Paleo-water Depth Cretaceous

0 1,000 Meters Jurassic 200 40 Sediment-Water Interface Temperature 2,000 Triassic Oil Immature Gas Overmature 20 3,000 Degrees Celsius

0 Burial depth, in meters 7 Heat flow Triassic Permian magmatic 4,000 activity 0

basin Cambrian Foreland Milliwatts, per suare meter Passive margin 2 ,000

Figure 5. Burial history model for pseudowells in the Lena-Anabar Basin Province assessment units (AUs), depicting thermal maturity. Locations of wells shown in figure 2. A, Petroleum system model for Lena-Anabar Basin AU northern pseudowell (shown in figure 3A) under scenario 1, the base case, in which there is nondeposition of a middle and late Paleozoic section, followed by deposition, petroleum generation, and accumulation during the Permian and Mesozoic. B, Petroleum system model for Lena-Anabar Basin AU northern pseudowell (shown in figure 3A) under scenario 2, the worst case, in which there is deposition of a middle and upper Paleozoic section with petroleum generation and accumulation, followed by middle to late Paleozoic erosion. C, Petroleum system model for Lena-Anabar Basin AU for southern pseudowell (shown in figure 3B). Ro, vitrinite reflectance, in percent (%). Data from Duchkov and others (1982); Polyakova and others (1986); and Shishkin and Isaev (1999). Petromod references: Integrated Exploration Systems (2008); Sweeney and Burnham (1990); and Wygrala (1989).—Continued Geology and Assessment of Undiscovered Oil and Gas Resources of the Lena-Anabar Basin Province, 2008 11

Reservoir and Seal Rocks rocks was deposited. However, preservation of petroleum accumulations would be low because of pre-Permian erosion The main reservoir and seal rocks in the northern part of (a worst-case scenario). Proterozoic and Cambrian source the Lena-Anabar Basin Province are inferred to be similar to rocks, as well as Permian and Mesozoic source rocks, proba- those in the neighboring Khatanga Saddle and include Upper bly generated petroleum during the Mesozoic before compres- Permian-Triassic sandstone with a Lower Triassic (Olenekian) sional deformation along the Olenek fold-and-thrust belt when mudstone seal. However, most Triassic clastic rocks have rela- the basin fill was greatest. tively poor reservoir quality (G.F. Ulmishek, oral commun., Petroleum from Proterozoic or Cambrian source rocks 2006). Lower Jurassic lithic and arkosic sandstone with is postulated to have migrated vertically and longitudinally 8–30 percent porosity is a potential reservoir where present. along faults and fractures because matrix permeability is low Although Vendian rocks, as well as Cambrian reefs and and might not be sufficient for migration. However, petro- reef-associated facies, might provide adequate reservoirs leum most likely migrated by long-distance lateral migration (Shishkin and Isaev, 1999), potential seal rocks are presently along permeable carrier beds southward and updip. Extensive unknown. Reservoir rocks containing bitumen in the Lena- bitumen deposits occur in upper Proterozoic, Cambrian, and Anabar Basin Province include karsted Upper Cambrian car- the unconformably overlying Permian rocks on both the east bonate rocks (Lopar Formation) and basal Permian sandstone and west margins of the province. Numerous other bitumen and siltstone that directly, but unconformably, overlie Cam- occurrences and natural gas shows in wells have been identi- brian rocks (Ivanov, 1979). fied throughout the province. The source of the bitumen is inferred to be Proterozoic and Cambrian mudstone, although some studies (Ivanov, 1979 for example) suggest that Permian Traps and Timing mudstone is the source. Basement normal faults associated with Proterozoic and Paleozoic extension, as well as anticlines, thrust-fault structures, and inverted basement blocks that formed during Assessment Units Cretaceous deformation could provide traps in downdip areas of the northern part of the province. Stratigraphic pinchout Three AUs—the Lena-Anabar Basin, Lena-Anabar Basin traps and “tar mat” traps are inferred to exist updip, as well as Updip, and Sukhan-Motorchun Riphean Rift—were defined traps with basement-associated normal faults and those related for the Lena-Anabar Basin Province. In this study, an AU is to reef facies (Ivanov, 1979; Shishkin and Isaev, 1999). Within the Proterozoic rift/sag areas, potential traps include grabens defined as a volume of rock within the TPS that has similar and faults related to rift structures. geologic characteristics. The estimated numbers and sizes of According to petroleum-generation models, maturation undiscovered oil and gas fields in each AU are reported in of Proterozoic and Cambrian source rocks occurred during the appendixes 1 through 3, and the geologic analog data used to Paleozoic, assuming that a sufficient thickness of Paleozoic evaluate the AUs are summarized in table 1.

Table 1. Geologic analogs used in the assessment of the Lena-Anabar Basin Assessment Unit.

[Analog data from Charpentier and others, 2008] Province name Structural setting Trap system Depositional system (assessment unit number) Foreland basins Middle Caspian Basin (11090101) Compressional Compressional anticlines, folds, thrusts Carbonate shelf; paralic clastics Amu-Darya Basin (11540101) Compressional Compressional anticlines, folds, thrusts; Paralic clastics; carbonate shelf basement-involved block structures Amu-Darya Basin (11540102) Passive Compressional anticlines, folds, thrusts; Paralic clastics; carbonate shelf Stratigraphic undeformed Amu-Darya Basin (11540103) Compressional Compressional anticlines, folds, thrusts Paralic clastics Rub Al Khali Basin (20190101) Compressional; Compressional anticlines, folds, thrusts Carbonate shelf Extensional Rub Al Khali Basin (20190102) Compressional Compressional anticlines, folds, thrusts; Carbonate shelf salt-induced structures Rub Al Khali Basin (20190103) Compressional Compressional anticlines, folds, thrusts Carbonate shelf Zagros Fold Belt (20300101) Compressional Compressional anticlines, folds, thrusts Continental clastics; carbonate shelf Zagros Fold Belt (20300102) Compressional Compressional anticlines, folds, thrusts Carbonate shelf; continental clastics 12 The 2008 Circum-Arctic Resource Appraisal

Table 1. Geologic analogs used in the assessment of the Lena-Anabar Basin Assessment Unit. —Continued

Province name Structural setting Trap system Depositional system (assessment unit number) Zagros Fold Belt (20300201) Compressional Compressional anticlines, folds, thrusts Carbonate shelf Junggar Basin (31150101) Compressional Compressional anticlines, folds, thrusts; Continental clastics basement-involved block structures Sichuan Basin (31420101) Compressional Compressional anticlines, folds, thrusts Carbonate shelf Tarim Basin (31540101) Compressional Compressional anticlines, folds, thrusts; Carbonate shelf; paralic clastics basement-involved block structures North Carpathian Basin (40470101) Passive Compressional anticlines, folds, thrusts Paralic clastics; slope, clinoforms, turbidites North Carpathian Basin (40470201) Compressional Compressional anticlines, folds, thrusts Paralic clastics; slope, clinoforms, turbidites San Jorge Basin (60580102) Compressional Compressional anticlines, folds, thrusts Paralic clastics Middle Magdalena (60900101) Compressional Compressional anticlines, folds, thrusts Paralic clastics Middle Magdalena (60900102) Compressional Compressional anticlines, folds, thrusts Paralic clastics Llanos Basin (60960101) Compressional; Compressional anticlines, folds, thrusts Extensional Llanos Basin (60960102) Compressional; Compressional anticlines, folds, thrusts Extensional East Venezuela Basin (60980101) Compressional Compressional anticlines, folds, thrusts Paralic clastics East Venezuela Basin (60980102) Compressional Compressional anticlines, folds, thrusts Paralic clastics Maracaibo Basin (60990102) Compressional Compressional anticlines, folds, thrusts Paralic clastics Greater Antilles Deformed Belt Compressional Compressional anticlines, folds, thrusts Carbonate shelf (61170101) Rifted passive margins Timan-Pechora Basin (10080102) Compressional Basement-involved block structures; pa- Paralic clastics; carbonate shelf leogeomorphic Timan-Pechora Basin (10080103) Compressional Compressional anticlines, folds, thrusts Paralic clastics; carbonate shelf Volga-Ural Region (10150101) Passive Basement-involved block structures; pa- Paralic clastics; carbonate shelf leogeomorphic Volga-Ural Region (10150102) Compressional Basement-involved block structures Paralic clastics; carbonate shelf Middle Caspian Basin (11090101) Compressional Compressional anticlines, folds, thrusts Carbonate shelf; paralic clastics Amu-Darya Basin (11540101) Compressional Compressional anticlines, folds, thrusts; Paralic clastics; carbonate shelf basement-involved block structures Nepa-Botuoba Arch (12100101) Compressional Basement-involved block structures; strati- Paralic clastics; carbonate shelf graphic undeformed Ma’Rib-Al Jawf/Masila Basin Extensional Extensional grabens and other structures Paralic clastics; carbonate shelf (20040101) related to normal faulting Fahud Salt Basin (20160201) Compressional; Compressional anticlines, folds, thrusts Paralic clastics; carbonate shelf Extensional margin, reefs Zagros Fold Belt (20300101) Compressional Compressional anticlines, folds, thrusts Carbonate shelf margin, reefs, slope, clinoforms, turbidites Zagros Fold Belt (20300102) Compressional Compressional anticlines, folds, thrusts Continental clastics; carbonate shelf Pelagian Basin (20480101) Compressional; Extensional grabens and other structures Carbonate shelf; continental Extensional related to normal faulting; transtensional clastics and transpressional Pelagian Basin (20480201) Compressional; Extensional grabens and other structures Carbonate shelf; paralic clastics Extensional related to normal faulting; transtensional and transpressional Tarim Basin (31540101) Compressional Compressional anticlines, folds, thrusts; Paralic clastics; carbonate shelf basement-involved block structures Bombay (80430101) Extensional Basement-involved block structures; strati- Paralic clastics; carbonate shelf graphic undeformed Paralic clastics; carbonate shelf margin, reefs Geology and Assessment of Undiscovered Oil and Gas Resources of the Lena-Anabar Basin Province, 2008 13

Lena-Anabar Basin Assessment Unit 0.6 and 0.4. The two scenarios are (1) base case—nondeposition of a middle and late Paleozoic section followed by deposition The Lena-Anabar Basin AU coincides with a foreland and maturation during the Permian and Mesozoic, and accu- basin that is shallow to the south and west and deepens to the mulation; and (2) worst case—deposition of a middle and late north and east. The basin and AU are bounded on the north by Paleozoic section with petroleum generation and accumula- the deformation front of the Olenek fold-and-thrust belt, on tion, followed by middle to late Paleozoic erosion. The timing the south by the approximate limit of effective petroleum-gen- of petroleum generation with respect to trap formation, and erating thickness (3 to 4 km) of Permian and Mesozoic rocks, preservation of petroleum in accumulations, is unknown. In on the east by the Olenek High, and on the west by the Anabar addition, the occurrence of migrated petroleum might indicate Anticlise. Stratigraphically, the AU includes the entire Protero- that traps did not exist for accumulation. zoic through Mesozoic sedimentary section. Approximately six wells have been drilled in this AU, a few of which flowed natural gas, but none are considered economic discoveries. Geologic Analogs for Assessment 2 The AU is approximately 55,000 km , 7 percent of which is Two analog sets from the USGS Analog Database located offshore in the Laptev Sea. (Charpentier and others, 2008) were used for the assessment Assessment of the Lena-Anabar Basin AU was based of the Lena-Anabar Basin AU: foreland basins (24 analogs) on two scenarios, because a single timing probability was and rifted passive margins and foreland basins with mixed insufficient to characterize the timing of petroleum genera- clastic and carbonate depositional systems (15 analogs). These tion in Proterozoic and Paleozoic source rocks with respect analogs were used to estimate the numbers and sizes of undis- to trap development. Permian and Mesozoic rocks directly covered fields (tables 1 and 2) in the AU. The analog sets have overlie Cambrian rocks throughout much of the AU, but discovered fields greater than the minimum size defined for whether a complete Paleozoic section was deposited and this assessment (50 MMBOE). Analog categories include both subsequently eroded is unknown. The two scenarios are: (1) a extensional and compressional structural settings and traps base case (having a 90 percent probability)—nondeposition of that have carbonate and clastic depositional systems (table 1). a middle and late Paleozoic section, followed by deposition, Four AUs are common to both analog sets. petroleum generation, and accumulation during the Permian Numbers of Undiscovered Fields.—The numbers of and Mesozoic; and (2) a worst case (having a 10 percent undiscovered oil and gas fields in the Lena-Anabar Basin AU probability)—deposition of a middle and upper Paleozoic (see appendix 1) were estimated by comparing field densities section with petroleum generation and accumulation, followed (estimated number of undiscovered fields plus number of by middle to late Paleozoic erosion. discovered fields >50 MMBOE per 1,000 km2) in the analog dataset (table 1). The density of discovered fields, which is Geological Analysis of Assessment Unit Probability generally smaller than the density of both discovered and undiscovered fields, was used to calibrate the estimated The probability that the Lena-Anabar Basin AU contains densities of undiscovered fields. Densities of 0.02, 0.4, and at least one field equal to or greater than the minimum field 1.8 (minimum, median, and maximum, respectively) were size of 50 million barrels of oil equivalent (MMBOE) is less estimated for scenario 1 (the base case) in the assessment of than 50 percent (0.50). As of 2007, no fields have been discov- the Lena Anabar Basin AU, because accumulations sourced ered in the Lena-Anabar Basin AU, and so source, reservoir, by Proterozoic and Paleozoic source rocks could exist in the and seal rocks, and trap configurations can only be inferred. Mesozoic section. For scenario 2 (the worst case), the median The probability of at least one field greater than the minimum and maximum densities were estimated to be approximately field size is estimated to be 0.48 for the base case scenario and half those of scenario 1 (0.02, 0.2, and 0.9 minimum, median, 0.32 for the worst case scenario. Assessment input data for this and maximum, respectively) because petroleum accumula- AU are reported in appendix 1 and summarized below. tions sourced from Proterozoic and Paleozoic rocks would Charge Probability.—A charge probability of 1.0 was exist only in the Paleozoic section. The median density of estimated for both scenarios because large accumulations of each scenario approximates the average density of the two bitumen are present in Cambrian and Permian rocks along analog datasets (from 0.2 for only discovered fields to 0.4 the northeastern and northwestern margins of the basin and for discovered plus undiscovered fields). Maximum densities because some of the exploration wells drilled in this AU approximate those of the analog datasets (1.1 to 1.6). An oil- flowed natural gas. rich oil/gas mixture of 0.9±0.1 was assumed for both scenarios Rock Probability.—A rock probability of 0.8 was esti- because Proterozoic and Paleozoic source rocks are oil prone, mated for both scenarios. The existence of reservoir rocks and large bitumen deposits occur along the flanks of the basin, traps is inferred but unproved. and gas-prone Mesozoic source rocks may not be fully mature Timing and Preservation Probability.—Timing and with respect to petroleum generation except in the deepest preservation probabilities were estimated for two scenarios, parts of the basin. 14 The 2008 Circum-Arctic Resource Appraisal

For scenario 1, the total minimum, median, and maxi- Stratigraphically, this AU includes the Proterozoic through mum numbers of undiscovered fields are 1, 20, and 100, Mesozoic sedimentary section. No wells have been drilled in respectively (see appendix 1). The estimated numbers of this AU, and only seismic exploration was conducted. The AU undiscovered oil fields are 1 (minimum), 20 (median), and 100 is approximately 43,000 km2 in area, with no offshore portion. (maximum); and the estimated numbers of undiscovered gas fields are 0 (minimum), 2 (median), and 20 (maximum). For scenario 2, the densities and estimated numbers of Geological Analysis of Assessment Unit undiscovered fields are half those of scenario 1. The total Probability minimum, median, and maximum numbers of undiscovered fields are 1, 10, and 50, respectively (see appendix 1). The No oil or gas fields have been discovered in the Lena- estimated numbers of undiscovered oil fields are 1 (minimum), Anabar Basin Updip AU. The likelihood that the AU contains 9 (median), and 50 (maximum); and the estimated numbers at least one field with accumulations equal to or greater than of undiscovered gas fields are 0 (minimum), 1 (median), and the minimum size (50 MMBOE) is 8 percent (0.08), which is 10 (maximum). below the minimum probability (0.10) defined for this assess- Sizes of Undiscovered Fields.—The minimum, median, ment, and so the AU was not quantitatively assessed. Input and maximum sizes of undiscovered oil and gas field sizes data for the Lena-Anabar Basin Updip AU are reported in in the Lena-Anabar Basin AU are reported in appendix 1. appendix 2 and summarized below. Minimum sizes of undiscovered fields defined for the AU are Charge Probability.—A charge probability of 1.0 was 50 million barrels (MMB) of crude oil and 300 billion cubic estimated because large amounts of bitumen are present in feet (BCF) of natural gas (6 BCF equals 1 MMBOE). The Cambrian and Permian rocks along the northeastern and north- median size of oil fields in the AU (125 and 100 MMBOE for western margins of the basin. scenarios 1 and 2, respectively) were estimated to approximate Rock Probability.—A rock probability of 0.8 was esti- the mean and median of the median size of the analog data mated because the presence and quality of reservoir and seal sets. The low-probability maximum oil field size, 2,500 MMBOE, rocks are unknown. is larger than the median of the largest discovered field size Timing and Preservation Probability.—A timing and in the analog datasets that includes rifted passive margin and preservation probability of 0.1 was estimated because the age foreland basins (1,700 MMBOE), whereas sizes of gas fields of trap formation with respect to timing of petroleum genera- are less (median sizes of 83 and 75 MMBOE; maximum tion is unknown. sizes of 167 MMBOE) because gas-prone Mesozoic source rocks may not be fully mature with respect to gas generation, resulting in incomplete trap fill. Sukhan-Motorchun Riphean Rift Expected Maximum Size of Undiscovered Fields.—The expected maximum oil field size (750 to 1,000 MMBOE) Assessment Unit is based on the distribution of sizes of discovered fields in the analog dataset, particularly the median of the maximum The Sukhan-Motorchun Riphean Rift AU, which is at discovered field sizes. The expected maximum gas field size the extreme updip edge of the Lena-Anabar Basin, includes (~100 MMBOE or 600 BCF) is again smaller because gas- the Proterozoic (Riphean) Sukhan and Motorchun rift-graben prone Mesozoic source rocks may not be fully mature with system. These grabens are filled with as much as 6 km of respect to gas generation. Proterozoic to Upper Cambrian carbonate and clastic rocks. In Petroleum Composition and Properties of Undiscovered the southern part of the Siberian craton, crude oil and natural Fields.—Coproducts and petroleum-quality properties were gas commonly flow from similar Proterozoic rocks and from estimated on the basis of global averages and data for the kimberlite dikes that penetrate these rocks. Stratigraphically, Baikal-Patom fold belt and the Proterozoic-Paleozoic AU of this AU includes the Proterozoic through Mesozoic sedimen- the neighboring Nepa-Botuoba High Province to the south. tary section. The extent of exploration is unknown, but some seismic exploration may have been conducted. The AU is approximately 27,000 km2 and is completely onshore. Lena-Anabar Basin Updip Assessment Unit

The Lena-Anabar Basin Updip AU, which is the updip Geological Analysis of Assessment Unit part of the Lena-Anabar Basin, is bounded on the east and Probability west by the Olenek High and the Anabar Anticlise, respectively. The Permian to Mesozoic clastic section significantly No oil or gas fields have been discovered in Sukhan- thins and the Cambrian carbonate section presumably over- Motorchun Riphean Rift AU. The likelihood that the AU lies crystalline or metamorphic basement rocks. Much of contains at least one field with accumulations equal to or the pre-Permian Paleozoic section is absent, owing to either greater than the minimum field size (50 MMBOE) is 7 percent nondeposition or erosion. Proterozoic rocks fill rift grabens. (0.07), which is below the minimum probability (0.10) defined Geology and Assessment of Undiscovered Oil and Gas Resources of the Lena-Anabar Basin Province, 2008 15

Table 2. Field densities, median oil and gas field sizes, and exploration maturities of geologic analogs used in the Lena-Anabar Basin Assessment Unit assessment. [Analog data from Charpentier and others (2008). Foreland basins analogs listed in table 1. Asterisk (*), not reported in analog database. Gas volumes are nonassociated. MMBOE, million barrels of oil equivalent] Field density (fields >50 MMBOE Field size Exploration maturity Maximum per 1,000 km2) distribution (percent petroleum Province name (assessment unit number) field size *Discovered Discovered and (median size equivalent volume in (MMBOE) fields undiscovered fields >50 MMBOE) fields >50 MMBOE) Foreland basins Middle Caspian Basin (11090101) 0.38 1.15 116 61 Amu-Darya Basin (11540101) 0.12 0.13 111 94 Amu-Darya Basin (11540102) 0.17 0.29 110 97 Amu-Darya Basin (11540103) 0.08 0.09 149 96 Rub Al Khali Basin (20190101) 0.09 0.18 204 90 Rub Al Khali Basin (20190102) 0.54 0.80 175 95 Rub Al Khali Basin (20190103) 0.27 0.55 109 54 Zagros Fold Belt (20300101) 0.20 0.57 162 79 Zagros Fold Belt (20300102) 0.19 0.59 126 83 Zagros Fold Belt (20300201) 0.30 1.55 213 57 Junggar Basin (31150101) 0.11 0.17 121 98 Sichuan Basin (31420101) 0.07 0.12 98 89 Tarim Basin (31540101) 0.02 0.13 112 14 North Carpathian Basin (40470101) 0.22 0.27 119 99 North Carpathian Basin (40470201) 0.09 0.10 77 98 San Jorge Basin (60580102) 0.07 0.29 124 99 Middle Magdalena (60900101) 1.13 1.25 177 99 Middle Magdalena (60900102) 0.73 0.92 115 91 Llanos Basin (60960101) 0.24 0.44 123 58 Llanos Basin (60960102) 0.09 0.22 147 66 East Venezuela Basin (60980101) 0.64 1.38 187 73 East Venezuela Basin (60980102) 0.07 0.46 90 16 Maracaibo Basin (60990102) 0.44 0.60 112 90 Greater Antilles Deformed Belt (61170101) 0.02 0.03 102 67 Median 0.18 0.37 120 89 874 Mean 0.26 0.51 132 78 6,926 Rifted passive margins Timan-Pechora Basin (10080102) 0.26 0.44 115 74 Timan-Pechora Basin (10080103) 0.01 0.23 103 53 Volga-Ural Region (10150101) 0.25 0.29 114 100 Volga-Ural Region (10150102) 0.14 0.14 116 100 Middle Caspian Basin (11090101) 0.38 1.15 116 61 Amu-Darya Basin (11540101) 0.12 0.13 111 94 Nepa-Botuoba Arch (12100101) 0.02 0.07 117 76 Ma’Rib-Al Jawf/Masila Basin (20040101) 0.20 0.41 100 66 Fahud Salt Basin (20160201) 0.23 0.28 223 92 Zagros Fold Belt (20300101) 0.20 0.57 162 79 Zagros Fold Belt (20300102) 0.19 0.59 126 83 Pelagian Basin (20480101) 0.12 0.19 157 94 Pelagian Basin (20480201) 0.01 0.02 63 66 Tarim Basin (31540101) 0.02 0.13 112 14 Bombay (80430101) 0.06 0.11 106 82 Median 0.14 0.23 115 79 1,666 Mean 0.15 0.32 123 76 8,007 Summary statistics for all analogs Median 0.15 0.29 116 86 1,025 Mean 0.22 0.43 129 78 5,810 Maximum 1.13 1.55 223 100 16 The 2008 Circum-Arctic Resource Appraisal for this assessment, and so the AU was not quantitatively 95-percent probability (F95) of 0 MMB and a 5-percent assessed. The input data for this AU are reported in appendix 3 probability (F5) of 7,207 MMB. Given that the aggregated AU and summarized below. probability is 0.462 for a field of minimum size, the probability Charge Probability.—A charge probability of 0.9 was that no crude oil or natural gas resources exist in this AU is 0.50 estimated because Proterozoic source rocks likely exist within (see table 3). The mean volume of undiscovered nonassociated the rift grabens. natural gas resources is 605 BCF, with an F95 of 0 BCF and an F5 Rocks Probability.—A rock probability of 0.8 was esti- of 2,538 BCF. The largest expected undiscovered oil field size is mated because the presence and quality of reservoir and seal ~731 MMB, and the largest expected undiscovered gas field size rocks are unknown. is ~563 BCF. The total estimated mean undiscovered petroleum Timing and Preservation Probability.—A timing and resources in the Lena-Anabar Basin Province are the same as for preservation probability of 0.1 was estimated because the timing of the Lena-Anabar Basin AU (table 3). trap formation with respect to petroleum generation is unknown. The geologic probabilities of the AUs in this study were In addition, oil and natural gas derived from rift grabens during the determined based on a consideration of the geology of the Paleozoic probably would not be preserved because of erosion and province, but also from the geologic probabilities assigned absence of adequate seals, such as evaporites. to AUs during the assessment of all Arctic basins. Thus, the probabilities were consistently applied throughout the Arctic for this assessment project. Lena-Anabar Basin Province Assessment Results Acknowledgments

The assessment results for the Lena-Anabar Basin AUs We are extremely grateful to the USGS library staff for in the Lena-Anabar Basin Province are summarized in table 3. their help in obtaining rare, hard-to-find geologic articles from Estimates represent undiscovered, technically recoverable, the Russian scientific literature. We also thank Feliks Persits conventional petroleum resources. for Geographic Information System (GIS) support, and Donald The mean undiscovered crude oil resource in the Lena- L. Gautier and Gregory F. Ulmishek for their reviews of the Anabar Basin AU is estimated to be 1,913 MMB, with a manuscript, which greatly improved this report.

Table 3. Assessment results for the Lena-Anabar Basin Province (conventional undiscovered resources). [MMB, million barrels; BCF, billion cubic feet. Results shown are fully risked estimates. For gas fields, all liquids are included under the natural gas liquids (NGL) catagory. F95 denotes a 95-percent chance of at least the amount tabulated and so on for F50 and F5. Fractiles are additive under the assumption of perfect positive correlation. AU, assessment unit. TPS, total petroleum system. NA, not applicable] Total undiscovered AU prob- Field Oil (MMB) NGL (MMB) Assessment units resources gas (BCF) ability type F95 F50 F5 Mean F95 F50 F5 Mean F95 F50 F5 Mean Lena-Anabar Basin Province Proterozoic-Paleozoic-Mesozoic composite TPS Lena-Anabar Basin AU 0.480 Oil 0 0 7,451 2,074 0 0 6,174 1,628 0 0 169 44 Scenario 1, 90 percent probability Gas NA NA NA NA 0 0 2,693 654 0 0 73 17 Lena-Anabar Basin AU 0.320 Oil 0 0 2,611 526 0 0 2,143 416 0 0 58 11 Scenario 2, 10 percent probability Gas NA NA NA NA 0 0 993 195 0 0 28 5 Lena-Anabar Basin AU 0.462 Oil 0 0 7,207 1,913 0 0 6,022 1,502 0 0 163 40 aggregate* Gas NA NA NA NA 0 0 2,538 605 0 0 69 16 Lena-Anabar Updip AU 0.080 Not quantitatively assessed Sukhan-Motorchun 0.072 Not quantitatively assessed Riphean Rift AU Total undiscovered 0 0 7,207 1,913 0 0 8,560 2,170 0 0 232 56 petroleum resources *Aggregate means for the entire assessment unit equal the means times the scenario probability of each scenario. Geology and Assessment of Undiscovered Oil and Gas Resources of the Lena-Anabar Basin Province, 2008 17

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Appendix files are available online only, and may be accessed athttps://doi.org/10.3133/pp1824T .

Appendix 1. Assessment input data for Lena-Anabar Basin Assessment Unit. A. Base case scenario (scenario 1). B. Worst case scenario (scenario 2).

Appendix 2. Assessment input data for Lena-Anabar Basin Updip Assessment Unit.

Appendix 3. Assessment input data for Sukhan-Motorchun Riphean Rift Assessment Unit. Klett and Pitman—Geology and Assessment of Undiscovered Oil and Gas Resources of the Lena-Anabar Basin Province, 2008—Professional Paper 1824 ISSN 2330-7102 (online) https://doi.org/10.3133/pp1824T