Circum-Arctic Resource Appraisal: Estimates of Undiscovered Oil and Gas North of the Arctic Circle he U.S. Geological Survey (USGS) Thas completed an assessment of undiscovered conventional oil and gas resources in all areas north of the Arctic Circle. Using a geology- based probabilistic methodology, the USGS estimated the occurrence of undiscovered oil and gas in 33 geologic provinces thought to be prospective for petroleum. The sum of the mean estimates for each province indicates that 90 billion barrels of oil, 1,669 trillion cubic feet of natural gas, and 44 billion barrels of natural gas liquids may remain to be found in the Arctic, of which approximately 84 percent is expected to occur in offshore areas. Overturned sedimentary rocks of the Lisburne Group under a midnight rainbow near Galbraith Lake, Alaska, summer 2001. USGS photo by David Houseknecht. Introduction opment, which will be important in many of geographically largest unexplored prospective In May 2008 a team of U.S. Geological the assessed areas. So-called nonconventional area for petroleum remaining on Earth. Survey (USGS) scientists completed an ap- resources, such as coal bed methane, gas hy- praisal of possible future additions to world drate, oil shale, and tar sand, were explicitly Methodology oil and gas reserves from new field dis- excluded from the study. Full details of the A newly compiled map of Arctic sedimen- coveries in the Arctic. This Circum-Arctic CARA study will be published later. tary basins (Arthur Grantz and others, un- Resource Appraisal (CARA) evaluated the A number of onshore areas in Canada, Rus- published work) was used to define geologic petroleum potential of all areas north of sia, and Alaska already have been explored provinces, each containing more than 3 km of the Arctic Circle (66.56° north latitude); for petroleum, resulting in the discovery of sedimentary strata. Assessment units (AUs)— quantitative assessments were conducted more than 400 oil and gas fields north of the mappable volumes of rock with common in those geologic areas considered to have Arctic Circle. These fields account for ap- geologic traits—were identified within each at least a 10-percent chance of one or more proximately 240 billion barrels (BBOE) of province and quantitatively assessed for significant oil or gas accumulations. For the oil and oil-equivalent natural gas, which is petroleum potential. Because of the sparse purposes of the study, a significant accu- almost 10 percent of the world’s known con- seismic and drilling data in much of the mulation contains recoverable volumes of ventional petroleum resources (cumulative Arctic, the usual tools and techniques used in at least 50 million barrels of oil and/or oil- production and remaining proved reserves). USGS resource assessments, such as discov- equivalent natural gas. The study included Nevertheless, most of the Arctic, especially ery process modeling, prospect delineation, only those resources believed to be recov- offshore, is essentially unexplored with respect and deposit simulation, were not generally erable using existing technology, but with to petroleum. The Arctic Circle encompasses applicable. Therefore, the CARA relied on the important assumptions for offshore about 6 percent of the Earth’s surface, an area a probabilistic methodology of geological areas that the resources would be recover- of more than 21 million km2 (8.2 million mi2), analysis and analog modeling. A world able even in the presence of permanent sea of which almost 8 million km2 (3.1 million analog database (Charpentier and others, ice and oceanic water depth. No economic mi2) is onshore and more than 7 million km2 2008) was developed using the AUs defined considerations are included in these initial (2.7 million mi2) is on continental shelves in the USGS World Petroleum Assessment estimates; results are presented without under less than 500 m of water. The extensive 2000 (USGS World Assessment Team, 2000). reference to costs of exploration and devel- Arctic continental shelves may constitute the [Continued on back page] U.S. Department of the Interior USGS Fact Sheet 2008-3049 U.S. Geological Survey 2008 PETROLEUM POTENTIAL OF ASSESSMENT UNITS AND PROVINCES IN THE CIRCUM-ARCTIC In the Circum-Arctic Resource Appraisal (CARA), 33 provinces were examined, of which 25 were judged to have a 10-percent or great- er probability of at least one significant undiscovered petroleum accumulation in any constituent assessment unit (AU) and were there- fore quantitatively assessed. Shown in these three maps are the relative probabilities for all assessment units assessed and the estimated relative potentials for undiscovered oil and gas in the assessed provinces. 0 º 90º E 90º W JMM MZB NM EGR TPB BP NZAA EBB WGEC A R C T I C C I R C L E WSB NGS 180º NKB 90º E Figure 1. Assessment units (AUs) in the Circum-Arctic Resource Appraisal (CARA) color-coded YK EB by assessed probability of the presence of at least one undiscovered oil and/or gas field with TUN recoverable resources greater than 50 million barrels of oil equivalent (MMBOE). Probabilities for SB AUs are based on the entire area of the AU, including any parts south of the Arctic Circle. LM NWLS FS LA PROBABILITY LSS (percent) AM CB NWC LV VLK 100 ESS 50–100 NCWF ZB 30–50 AA 10–30 LS YF <10 HB Area of low petroleum potential 0 º JMM MZB NM EGR TPB BP NZAA EBB WGEC WSB NGS NKB 90º E 90º W YK EB TUN SB LM NWLS FS LA LSS AM CB NWC LV VLK ESS NCWF 0 º ZB AA LS YF HB JMM A R C T I C C I R C L E MZB NM 180º EGR Figure 3. Provinces in the Circum-Arctic Resource Appraisal (CARA) color-cod- TPB BP ed for mean estimated undiscovered oil in oil fields. Only areas north of the Arctic Circle are included in the estimates. Province labels are the same as in table 1. NZAA EBB WGEC UNDISCOVERED OIL WSB (billion barrels) NGS >10 NKB 1-10 90º W YK EB <1 Area not quantitatively assessed TUN SB Area of low petroleum potential LM NWLS FS LA Figure 2. Provinces in the Circum-Arctic Resource Appraisal (CARA) color- LSS coded for mean estimated undiscovered gas. Only areas north of the Arctic AM Circle are included in the estimates. Province labels are the same as in table 1. CB NWC LV VLK ESS UNDISCOVERED GAS NCWF (trillion cubic feet) ZB AA LS YF HB >100 A R C T I C 6–100 C I R C L E <6 Area not quantitatively assessed 180º Area of low petroleum potential [Continued from front page] The database includes areas that account for In addition to the AU probability, the ments are not reported here, but the AUs are more than 95 percent of the world’s known oil number of accumulations, the size-frequency shown as mapped areas on figure 1, where and gas resources outside the United States. distribution of accumulations, and the relative they are color-coded for the probability of For each assessment unit, the CARA team likelihood of oil versus gas were assessed for at least one undiscovered accumulation of assessed the probability (AU probability) that each AU and combined by means of a Monte minimum size. The provinces are listed in a significant oil or gas accumulation was pres- Carlo simulation. The probabilistic results re- table 1, in ranked order of total mean esti- ent. This evaluation of AU probability was flect the wide range of uncertainty inherent in mated oil-equivalent volumes of undiscov- based on three geologic elements: (1) charge frontier geological provinces such as those of ered oil, gas, and natural gas liquids (NGL). (including source rocks and thermal maturi- the Arctic. The provinces are shown in figures 2 and 3, ty), (2) rocks (including reservoirs, traps, and where they have been color-coded with re- seals), and (3) timing (including the relative Results—Resource Summary spect to fully risked (including AU probabili- ages of migration and trap formation, as well Within the area of the CARA, 25 provinc- ties) potential for gas and oil, respectively. as preservation). Each assessment unit was es were quantitatively assessed; 8 provinces More than 70 percent of the mean undis- ranked according to its AU probability; those were judged to have less than a 10-percent covered oil resources is estimated to occur in AUs judged to have less than a 10-percent probability of at least one significant accu- five provinces: Arctic Alaska, Amerasia Ba- probability of a significant accumulation were mulation in any AU and were, therefore, not sin, East Greenland Rift Basins, East Barents not quantitatively assessed. assessed. Results of individual AU assess- Basins, and West Greenland–East Canada. More than 70 percent of the undiscovered natural gas is estimated to occur in three prov- inces, the West Siberian Basin, the East Bar- Table 1. Summary of Results of the Circum-Arctic Resource Appraisal ents Basins, and Arctic Alaska. It is further [MMBO, million barrels of oil; BCFG, billion cubic feet of natural gas; MMBNGL, million barrels of natural gas liquids; NQA, not estimated that approximately 84 percent of quantitatively assessed. Results shown are fully risked mean estimates. For gas accumulations, all liquids are included as NGL the undiscovered oil and gas occurs offshore. (natural gas liquids). Provinces are listed in ranked order of total barrels of oil and oil-equivalent natural gas (BOE).] The total mean undiscovered conventional oil and gas resources of the Arctic are estimated Province Province Oil Total Gas NGL BOE to be approximately 90 billion barrels of oil, Code (MMBO) (BCFG) (MMBNGL) (MMBOE) 1,669 trillion cubic feet of natural gas, and 44 WSB West Siberian Basin 3,659.88 651,498.56 20,328.69 132,571.66 billion barrels of natural gas liquids.