National Petroleum Reserve In Alaska Research Articles

Unusually thick freshwater ice and its impacts on aquatic resources in the National Petroleum Reserve in Alaska (NPR-A) during the winter of 2020–2021

Despite a long-term thinning trend in freshwater ice in northern Alaska, cold low-snow cover winters can still emerge to grow thick ice. In 2021, we observed abnormally thick ice by winter's end on lakes and rivers throughout the Fish Creek Watershed in the National Petroleum Reserve in Alaska. This recent and anomalous winter presented an opportunity to assess how such conditions, more typical of many decades previous, affected aquatic habitat and winter water supply. Observed maximum ice thickness in 2021 of 1.9 m closely matched low-snow ice growth simulations, whereas previous records averaged 1.5 m and more closely matched high-snow ice growth simulations. The resulting extent of bedfast lake ice from late winter synthetic aperture radar (SAR) analysis in 2021 was the highest on record since 1992. This SAR analysis suggests a 33% reduction in liquid water below ice by lake surface area compared with the recent thin-ice winter of 2018 (1.2 m). Together, these results help place the cold, low-snow winter of 2020–2021 in context of the long-term trend toward warmer, snowier winters that appear to becoming more common in Arctic Alaska.

Lake basins drive variation in catchment‐scale runoff response over a decade of increasing rainfall in Arctic Alaska

AbstractLakes basins cover wide extents of many Arctic Coastal Plain (ACP) landscapes and thus are integral components of hydrological processes. Observed variation in runoff responses between two adjacent catchments being monitored pre‐ and post‐development in the National Petroleum Reserve in Alaska (NPR‐A) suggested the need to better understand how lake basins, both current lakes and drained lake basins (DLBs), modify flow regimes. A progressive increase in summer rainfall over this monitoring period, 2009–2019, also provided an opportunity to assess how watershed characteristics interacted with hydrologic intensification. Stream gauging records from eight other nearby catchments ranging from 16 to 270 km2 with varying extents of lakes (14%–47%) and DLBs (5%–57%) expanded our analysis of ACP hydrology. Wider DLB extent corresponded to higher and more rapid snowmelt peak flows and this relationship also became evident during rainstorms in summers with high antecedent surface storage. Mean annual runoff and summer low‐flows were best explained by extent of connected lakes. Over this period of increasing summer rainfall, all hydrograph responses became more closely related to the full extent of lake basins suggesting expanding connectivity. Our final year of complete hydrologic records in 2019 was punctuated by a 30‐mm late‐summer rainfall event, which generated flow peaks nearly exceeding snowmelt runoff at several gauges, specifically ones with high extent of DLBs. This rain‐event response underscored the increasing need to include both lakes and DLBs in models of ACP watershed hydrology. An improved understanding of catchment‐scale controls on variable hydrologic responses will be increasingly essential for mitigating hazards to new and existing development, predicting floods, drought, and water supply, and protecting aquatic ecosystem functioning and habitat as the Arctic hydrologic cycle intensifies and development expands.

Simulation modeling accounts for uncertainty while quantifying ecological effects of development alternatives

AbstractWildlife management often involves trade‐offs between protecting species and allowing human activities and development. Ideally, these decisions are guided by scientific studies that quantify the impacts of proposed actions on the environment. However, critical information to assess impacts of proposed activities may be lacking, such as certainty in where actions will take place, which may hinder a robust impact assessment. To address this issue, we present the Development Impacts Analysis (DIA), which employs Monte Carlo simulation modeling to quantify the environmental consequences of proposed development scenarios, while accounting for uncertainty in the exact location of future development. We applied the DIA to five proposed oil leasing management scenarios under a revised management plan for the National Petroleum Reserve—Alaska. For each management scenario with differing levels of proposed development (“alternatives”), oil production pads and roads were randomly simulated in proportion to estimated undiscovered oil and following alternative‐specific restrictions. We assessed habitat displacement for two caribou (Rangifer tarandus) herds, eight shorebird species, and black brant (Branta bernicla) based on reported responses to development, repeating the process 100 times for each alternative. Some habitat loss was reported for each proposed alternative, but the amount of impact varied by alternative and species. One caribou herd and most bird species indicated greatest effects in the alternative with the least restrictions on development and lesser impacts under more protective alternatives. Our results emphasized the importance of considering spatial variation in development effects and species‐specific differences when evaluating management proposals. The DIA quantified potential impacts on a suite of species under proposed management alternatives, while accounting for uncertainty in where development will occur and providing confidence intervals on estimated impacts. This illustrates that uncertainty need not preclude management decisions about establishment of broad land use restrictions prior to submission of project‐level proposals but can instead be explicitly incorporated into decision making. While no single management approach will likely benefit all species, use of tools such as the DIA allows managers to quantify trade‐offs among species and pursue approaches that balance the needs of various taxa and other management objectives.

Mapping Arctic Lake Ice Backscatter Anomalies Using Sentinel-1 Time Series on Google Earth Engine

Seepage of geological methane through sediments of Arctic lakes might contribute conceivably to the atmospheric methane budget. However, the abundance and precise locations of such seeps are poorly quantified. For Lake Neyto, one of the largest lakes on the Yamal Peninsula in Northwestern Siberia, temporally expanding regions of anomalously low backscatter in C-band SAR imagery acquired in late winter and spring have been suggested to be related to seepage of methane from hydrocarbon reservoirs. However, this hypothesis has not been verified using in-situ observations so far. Similar anomalies have also been identified for other lakes on Yamal, but it is still uncertain whether or how many of them are related to methane seepage. This study aimed to document similar lake ice backscatter anomalies on a regional scale over four study regions (the Yamal Peninsula and Tazovskiy Peninsulas; the Lena Delta in Russia; the National Petroleum Reserve Alaska) during different years using a time series based approach on Google Earth Engine (GEE) that quantifies changes of σ0 from the Sentinel-1 C-band SAR sensor over time. An algorithm for assessing the coverage that takes the number of acquisitions and maximum time between acquisitions into account is presented, and differences between the main operating modes of Sentinel-1 are evaluated. Results show that better coverage can be achieved in extra wide swath (EW) mode, but interferometric wide swath (IW) mode data could be useful for smaller study areas and to substantiate EW results. A classification of anomalies on Lake Neyto from EW Δσ0 images derived from GEE showed good agreement with the classification presented in a previous study. Automatic threshold-based per-lake counting of years where anomalies occurred was tested, but a number of issues related to this approach were identified. For example, effects of late grounding of the ice and anomalies potentially related to methane emissions could not be separated efficiently. Visualizations of Δσ0 images likely reflect the temporal expansions of anomalies and are expected to be particularly useful for identifying target areas for future field-based research. Characteristic anomalies that clearly resemble the ones observed for Lake Neyto could be identified solely visually in the Yamal and Tazovskiy study regions. All data and algorithms produced in the framework of this study are openly provided to the scientific community for future studies and might potentially aid our understanding of geological lake seepage upon the progression of related field-based studies and corresponding evaluations of formation hypotheses.

Preservation of organic carbon in the Cretaceous Hue Shale on the North Slope of Alaska: Insights from pyrite morphology

The Cretaceous Hue Shale is a condensed mudstone section of the Brookian sequence with type II and type III kerogen, and it is one of the major source rocks that fill the world-class conventional oil fields on the North Slope, Alaska. The bottom section of the Hue Shale is referred to as Gamma Ray Zone (GRZ) or Highly Radioactive Zone (HRZ) and believed to be the most organic-rich section. The thermal maturity increases from immature to over oil window towards the southwest. Although, the research on the Hue Shale as an unconventional shale reservoir is still at an early stage, where exploration activities are very limited. The Hue Shale thickens to the east in general. However, regional variations of thickness and more importantly total organic carbon (TOC) have been reported.In this research, a suite of nineteen core samples of the Hue Shale are selected. These cores are collected from six wells covering a wide spectrum of thermal maturity with four wells in the National Petroleum Reserve Alaska and two wells in the state land. A combined geochemical and petrographic methodology is utilized to address the regional redox conditions and the preservation of organic carbon. TOC, Tmax, hydrogen index, and oxygen index are acquired through pyrolysis to characterize the abundance, thermal maturity, the origin, and the evolution of organic matter. Scanning electron microscope (SEM) coupled with energy dispersive X-ray spectroscopy (EDS) is used to investigate the mineralogy and diagenesis of the Hue Shale. Pyrite crystal forms, and pyrite framboid size distributions are used as an indicator of the redox conditions during deposition. The results show substantial variance in oxygen levels in the water column. High abundance and small sizes of pyrite framboids, which indicates a depleted oxygen environment, show better preservation potential of organic matter.

E&P Notes (November 2020)

Shell Explores Plans for North Slope Development Dutch oil major Shell is looking to further develop its North Slope oil position in Alaska. The company’s offshore unit applied to form the West Harrison Bay Unit offshore from the National Petroleum Reserve–Alaska with plans for drilling and exploration. The proposed West Harrison Bay Unit comprises 18 leases in West Harrison Bay approximately 34 miles northwest of the Colville River Unit. Shell holds 100% working interest in those 18 leases, covering more than 78,000 acres in the proposed unit. The company is identifying partners to share in the risk and costs, with plans to drill exploration wells in the West Harrison unit with at least one sidetrack each in 2023 and 2024. Because economic uncertainty from the pandemic and oil-price crash made negotiations difficult with potential partners, Shell requested the initial West Harrison Bay exploration plan to be for 5 years to allow enough time to find a partner and improve its plan. The wells would target the Nanushuk oil formation first identified by the Repsol-Armstrong Energy partnership in the Pikka Unit. The shallow, conventional formation also forms the basis of ConocoPhillips’ large Willow oil prospect to the south of Harrison Bay and is believed by many in the industry to be prolific across much of the western North Slope. Shell has been operating in Alaska since the 1950s when it began exploration in the Cook Inlet Basin. It acquired the West Harrison Bay leases in 2012, and redirected focus to the leases in 2017, generating five standalone prospects in the Nanushuk and multiple leads in the Torok formation and Jurassic Alpine-like plays.

Evidence of Hydrological Intensification and Regime Change From Northern Alaskan Watershed Runoff

AbstractSnowmelt‐dominated runoff regimes have defined northern Alaskan rivers. Discharge records from three watersheds within the National Petroleum Reserve in Alaska (NPR‐A) span 19 years and capture three notable periods of changing runoff. In the first, 2001–2008, mean annual runoff (MAR) averaged 90 mm, characterized by sharp snowmelt runoff and summer drought. Over the next 7 years, larger MAR averaged 120 mm driven by high and early snowmelt runoff. The most recent 4 years, 2016–2019, had even higher MAR of 163 mm with high and sustained late summer flows. Hydrograph analysis suggests a shift toward rainfall‐dominated runoff in the most recent period compared to snowmelt‐dominated hydrographs in the previous two. Declining sea ice appears closely linked to increasing late summer precipitation and a shift toward rainfall runoff. Future development in the NPR‐A will require continued hydrological monitoring and planning to mitigate flood and erosion hazards, permafrost degradation, and ecosystem impairment.

Movements and habitat use of loons for assessment of conservation buffer zones in the Arctic Coastal Plain of northern Alaska

Oil and gas development in the Arctic Coastal Plain, Alaska, may pose threats to wildlife. Management guidelines within the National Petroleum Reserve-Alaska dictate buffer zones for coastal wildlife habitat and for breeding and foraging sites of yellow-billed loons (YBLOs; Gavia adamsii), a species of conservation concern. However, few data exist to assess the value of these buffer zones for YBLOs or for sympatrically breeding red-throated loons (RTLOs; G. stellata) and Pacific loons (PALOs; G. pacifica). We evaluated movements of these loons on the Arctic Coastal Plain to understand: 1) seasonal timing; 2) marine habitat use; and 3) spatial characteristics of breeding home ranges. We then used those findings to evaluate current management strategies in the context of loon biology. Compared to RTLOs and PALOs, YBLOs nested on larger lakes, stayed on them longer, had larger home ranges, but less frequently used the marine environment in summer. During autumn, YBLOs and PALOs were located farther from shore than during spring or summer, whereas RTLOs used the marine environment similarly during all three seasons. Management buffers established for YBLO nesting areas corresponded well with nest site space use of all three species, suggesting cross-taxa applicability of current management guidelines for nesting habitat. However, the majority of loon locations on the Arctic Coastal Plain were outside of coastal buffer zones established to protect fish and wildlife habitat within the National Petroleum Reserve-Alaska. These findings can inform assessment of conservation buffer zones to mitigate anthropogenic disturbance to loons in Alaska.

Classifying connectivity to guide aquatic habitat management in an arctic coastal plain watershed experiencing land use and climate change

ABSTRACT Habitat connectivity supports life history requirements of many arctic fish species during periods of flowing water. However, aquatic habitat connectivity is susceptible to change due to climate factors and land use, particularly in the 4,600 km2 Fish Creek Watershed (FCW) located in National Petroleum Reserve in Alaska. Varying degrees and mechanisms of connectivity between overwintering habitat and summer foraging habitat motivated us to assess and classify aquatic habitat connectivity to help inform management. Using geospatial analysis and field methods we classified processes affecting connectivity within riparian corridors and upstream channels. Results show the dominant geomorphic process affecting connectivity varied among river systems, providing general and catchment-specific guidance as to the distribution of important migratory fish habitat. Barriers to fish passage caused by subsurface flow were more common along river corridors with high channel migration rates, whereas wetland flowthrough was the most common barrier in upstream catchments throughout the FCW. Coupling both riparian and catchment connectivity showed that 28 percent of catchments were classified as having fish-passable connectivity, indicated by no barriers present in the riparian zone or upstream channels. Future work should evaluate how well this classification predicts fish habitat, is useful to resource management, and is applicable to other arctic watersheds.

The influence of chick production on territory retention in Arctic-breeding Pacific and Yellow-billed loons

Abstract Adult birds may use the production of offspring as a measure of habitat quality when prospecting for territories, increasing competition for productive territories. We evaluated the impact of breeding success on territory retention of Pacific (Gavia pacifica) and Yellow-billed (G. adamsii) loons in the National Petroleum Reserve-Alaska on the Arctic Coastal Plain of northern Alaska using mark–resight data and multi-state modeling. We also used behavioral observations of brood-rearing adult loons to quantify the frequency of visits by prospecting loons. We hypothesized that increased competition for productive territories would result in a decrease in territory retention rates. Territory retention rates the year following successful breeding attempts were only slightly lower (0.90) than after failed breeding attempts (0.93), and few territories were consistently successful across years. Overall territory retention rates were high (0.92) and similar for both species, suggesting that adults were able to defend their territories successfully. Males had higher territory retention rates than females, but we found no influence of mass (a possible proxy for fighting ability) on territory retention. These observations, coupled with the high frequency of visits by prospecting loons, provide additional evidence that site familiarity may provide advantages to territory holders. Quantifying territory retention behaviors may also inform land management decisions for oil and gas development in areas where loons are present. High territory retention rates, frequency of visits by prospectors, and limited habitat where new territories can be established suggest that breeding habitat in northern Alaska is saturated and may be limiting Yellow-billed Loon populations. In contrast, Pacific Loons attempting to acquire a territory may be able to form new territories on smaller, unoccupied lakes.

Territory occupancy by breeding yellow‐billed loons near oil development

ABSTRACTLess than 4,000 yellow‐billed loons (Gavia adamsii) breed in remote and disjunct locations in northern Alaska, USA. Over 75% of the United States population of yellow‐billed loons nests in the National Petroleum Reserve–Alaska (NPRA), where impending oil and gas development will intersect their breeding range. We investigated the relationship of recent oilfield development to occupancy of yellow‐billed loon territories by breeding pairs (indicated by active nests) and broods using 14 years of aerial surveys on the Colville River delta. We also evaluated the survey requirements prescribed by the Bureau of Land Management (BLM) for NPRA. We began aerial surveys for yellow‐billed loons in 1993, prior to construction of the Alpine oilfield in 1998, and followed territories through 2008, after construction of 2 additional satellite drill sites. We used records from 37 breeding territories on 36 lakes in model selection analyses to examine how habitat and disturbance factors (proximity to facilities and construction time period) influenced occupancy by breeding pairs and broods. Annually, 13 ± 2.5 (SE)% (n = 14 yr) of broods (n = 19) moved from nesting lakes to adjacent brood‐rearing lakes, and the remainder stayed in nesting lakes (n = 128). Lakes used for nesting and brood‐rearing were almost 25 times larger ( = 95.9 ± 25 ha, n = 23 lakes) than nesting lakes from which broods left ( = 4.0 ± 1.1 ha, n = 7 lakes, P < 0.001). Thirty‐eight percent of territories (n = 14 territories) were on lakes shared by >1 breeding pair. Lake type (deep open lakes with islands or polygonized margins, deep open lakes without islands or polygonized margins, and tapped lakes with high‐water connections) was the most influential covariate on occupancy by breeding pairs, and lake area was most influential on occupancy by broods. Time period and distance to facilities (as discrete zones at 1.6 km and 3.2 km and as linear distance) were factors in the highest‐ranked models for 5 of the 6 model sets that included disturbance parameters. Interaction terms for time period and distance to oilfield facilities were factors in 3 of 6 model sets. The pattern of occupancy of breeding territories, however, was not consistent with disturbance‐related effects. Occupancy of territories by breeding pairs was lower in the pre‐development period (lowest human activity) than in the latest development period (highest human activity) and higher in the zones near oilfield facilities than far from facilities. Occupancy of territories by broods was highest in the latest development period and similarly high in zones near and far from facilities. Application of BLM minimum survey requirements (3 yr with 2 surveys/yr) to the initial 3 years of surveys in this study resulted in detecting 81% of the known territories on the Colville River delta. The BLM restrictions on development were judged conservative in maintaining breeding territories around oilfield developments. Our results did not demonstrate displacement of nests or broods from long‐standing territories by oil development. Our findings suggest that territory occupancy by breeding pairs and broods of yellow‐billed loons on the Colville River delta was resilient to levels of human activity at recently constructed oilfield facilities. © 2018 The Authors. Journal of Wildlife Management published by Wiley Periodicals, Inc. on behalf of The Wildlife Society.

Sedimentary magnetic anomalies: Part 1 — The validity of short-wavelength, low-amplitude SEDMAG anomalies

Validation is important in any study of sedimentary high-frequency magnetic anomalies. Repeatability and good correlation of anomalies between lines of the same survey and lines from different surveys as well as maximum entropy spectral analysis are some of the approaches I used to verify and validate the geologic nature of these anomalies. Examples of such correlations from the National Petroleum Reserve in Alaska are used here for illustration. The filtered magnetic data used in these examples represent two surveys: the U.S. Department of Energy's low-level (120 m) National Uranium Resource Evaluation total field survey flown in 1980 and the high-level (650 m) high-sensitivity total field/vertical gradient survey flown in 1974 with measured vertical gradient. I will provide a general discussion on the magnetization of sediments as well as model studies illustrating the theoretical magnetic response of some typical sedimentary structures.

Distribution and occupancy of wolverines on tundra, northwestern Alaska

ABSTRACTUnderstanding wildlife distribution and habitat use is needed for effectively balancing resource development, wildlife conservation, and Alaska Native subsistence on the North Slope of Alaska, USA. This region includes the National Petroleum Reserve‐Alaska (NPR‐A), a 96,000‐km2remote area of largely undeveloped lands that is important for wildlife, including caribou (Rangifer tarandus), wolves (Canis lupus), and wolverines (Gulo gulo). We focused our study on spring distribution and occupancy of wolverines in the NPR‐A because a baseline distribution estimate is required to understand current distribution and track changes over time. We conducted aerial surveys of wolverine tracks in snow during March and April of 2014 and 2015, surveying over 84,400 km2using 100‐km2hexagonal sampling units. We used hierarchical Bayesian occupancy modeling to determine wolverine distribution and estimate probability of occupancy within each hexagon, relative to measured covariates with potential to affect either detection or occupancy. Probability of wolverine occupancy increased as well‐drained soils increased, suggesting that wolverines prefer drier areas or habitat features associated with well‐drained soils. In addition, as standard deviation of elevation increased, wolverine occupancy also increased, indicating that wolverines may prefer areas with more rugged and variable terrain. Mean elevation was not retained as a covariate in the best‐fitting model, supporting the importance of terrain ruggedness rather than elevation on wolverine distribution within the NPR‐A. Spatially, areas of highest wolverine occupancy occurred within the southern and northeastern portions of the study area, with lowest occupancy in the northern portion of the study area west of Teshekpuk Lake. Based on the spatial pattern of wolverine probability of occupancy, we proposed 4 potential wolverine management zones with varying priorities for monitoring and managing wolverine populations. © 2018 The Wildlife Society.

E&P Notes (February 2018)

E&P Notes Industry Poised for Stronger Performance in 2018 Joel Parshall, JPT Features Editor The global oil industry appears poised for stronger performance in 2018, having benefitted from the financial discipline and cost-cutting innovation driven by several years of low oil prices and looking ahead to somewhat more stable market conditions. While oil prices have recently risen above $60/bbl, likely reflecting a number of short-term supply disruptions and concerns over Middle East tensions, forecasts generally call for prices to fluctuate sustainably between $40/bbl and $60/bbl and end the year in the higher part of that range. “Higher prices in or above that range will increase supply as countries lessen compliance with production quotas and United States shale production keeps increasing,” said Moody’s Investors Services in its 2018 industry outlook. ‘Supergiant’ Zohr Gas Field Off Egypt Comes On Stream Matt Zborowski, Technology Writer Eni confirmed on 20 December that the Zohr field has started gas production from the Shorouk block offshore Egypt. The launch comes less than 2½ years after the Italian firm discovered the enormous deposit, which is estimated to hold more than 30 Tcf of gas in place. The field is flowing 350 MMcf/D and is slated to produce 1 Bcf/D by the middle of next year, Egypt’s petroleum ministry said. The project’s first phase includes six subsea wells, with gas transported 180 km to an onshore plant at Port Said for processing and use in Egypt’s national grid. The second phase will comprise 14 more wells to be drilled by the end of 2019. The field sits in 1500 m of water. Schlumberger Buys Weatherford’s US Fracturing Assets Weatherford has sold its US pressure pumping and pump-down perforating assets to Schlumberger for $430 million in cash, abruptly ending a planned joint venture that was to begin operations on 1 January. The parties agreed to revised deal terms that reflect an asset sale, abandoning the previously announced OneStim joint venture that had received US Department of Justice approval in November 2017. Schlumberger will take ownership of Weatherford’s US pressure pumping and pump-down perforating related facilities and supplier and customer contracts. Additionally, 100 Weatherford employees associated with the business will transfer to Schlumberger. Oil Discoveries Fall to Lowest Level in 70 Years Unconventional output may be booming, but the low oil prices of the past 3 years have led to the lowest level of oil discoveries in the past 70 years. Oil companies discovered less oil and gas in 2017—7 billion BOE—than any year on record, the Norwegian research firm Rystad Energy said in a December report. “We haven’t seen anything like this since the 1940s,” said Sonia MladÁ Passos, a senior analyst at Rystad. “We have to face the fact that the low discovered volumes on a global level represent a serious threat to the supply levels some 10 years down the road.” Big Discoveries Prompt US Agencies To Lift Recoverable Resource Estimates in Alaska Matt Zborowski, Technology Writer The US Department of the Interior (DOI) has increased its estimate of undiscovered, technically recoverable resources in parts of Alaska’s federal, state, and tribal lands and waters following recent, bigger-than-expected discoveries. The revisions include a large jump in estimated onshore oil resources. The assessment—conducted by DOI agencies the Bureau of Ocean Energy Management (BOEM), Bureau of Land Management, and US Geological Survey (USGS)—shows approximately 17.6 billion bbl of oil and 50 Tcf of gas in the National Petroleum Reserve-Alaska (NPR-A), the Western Beaufort Sea, nearby state and native lands, and state waters.

Evaluation of gas production potential from gas hydrate deposits in National Petroleum Reserve Alaska using numerical simulations

An evaluation of the gas production potential of Sunlight Peak gas hydrate accumulation in the eastern portion of the National Petroleum Reserve Alaska (NPRA) of Alaska North Slope (ANS) is conducted using numerical simulations, as part of the U.S. Geological Survey (USGS) gas hydrate Life Cycle Assessment program. A field scale reservoir model for Sunlight Peak is developed using Advanced Processes & Thermal Reservoir Simulator (STARS) that approximates the production design and response of this gas hydrate field. The reservoir characterization is based on available structural maps and the seismic-derived hydrate saturation map of the study region. A 3D reservoir model, with heterogeneous distribution of the reservoir properties (such as porosity, permeability and vertical hydrate saturation), is developed by correlating the data from the Mount Elbert well logs. Production simulations showed that the Sunlight Peak prospect has the potential of producing 1.53 × 109 ST m3 of gas in 30 years by depressurization with a peak production rate of around 19.4 × 104 ST m3/day through a single horizontal well. To determine the effect of uncertainty in reservoir properties on the gas production, an uncertainty analysis is carried out. It is observed that for the range of data considered, the overall cumulative production from the Sunlight Peak will always be within the range of ±4.6% error from the overall mean value of 1.43 × 109 ST m3. A sensitivity analysis study showed that the proximity of the reservoir from the base of permafrost and the base of hydrate stability zone (BHSZ) has significant effect on gas production rates. The gas production rates decrease with the increase in the depth of the permafrost and the depth of BHSZ. From the overall analysis of the results it is concluded that Sunlight Peak gas hydrate accumulation behaves differently than other Class III reservoirs (Class III reservoirs are composed of a single layer of hydrate with no underlying zone of mobile fluids) due to its smaller thickness and high angle of dip.

Reservoir Screening for EOR Potential for the Western North Slope, Alaska

The Western North Slope of Alaska is an oil-rich zone located in the Colville river unit close to the Eastern boundary of National Petroleum Reserve Alaska. With an objective to find better enhanced oil recovery solutions and improve recoveries, four reservoirs from the Western North Slope were screened for different enhanced oil recovery methods to find the most suitable option. Based on the initial screening, gas injection was found to be the preferred method. This was followed by the determination of optimum injection gas compositions for Western North Slope reservoirs and their rank, thereby developing a new ranking methodology for gas flooding projects. The work was accomplished via a combination of two custom developed Excel spreadsheets for the determination of minimum miscibility pressure and enrichment respectively and several numerical experiments carried out using a compositional reservoir simulator, the results of which were applied for parametric ranking of the four Western North Slope reservoirs.

40Ar/39Ar ages and geochemical characterization of Cretaceous bentonites in the Nanushuk, Seabee, Tuluvak, and Schrader Bluff formations, North Slope, Alaska

Diagenetically altered volcanic ash deposits (bentonites) found in Cretaceous terrestrial and marine foreland basin sediments have the potential to be used for chronostratigraphy and subsurface correlation across Alaska's North Slope. Detailed age and geochemical studies of these volcanogenic deposits may also shed light on the tectonic evolution of the Arctic. Though these bentonites have been previously studied, there are few published results for regional bentonite ages and geochemistry due to challenges of dating weathered volcanic ash. We analyzed mineral separates from cored bentonites recovered from wells in the National Petroleum Reserve Alaska. The analyses confirm that an intense period of volcanic ash deposition on Alaska's North Slope began by the late Albian and persisted throughout the Cenomanian, an interval of rapid progradation and aggradation in the Colville basin. These results also add to a sparse record of radioisotopic ages from the Nanushuk Formation. A bentonite preserved in delta plain sediments in the upper Nanushuk Formation dates to 102.6 ± 1.5 Ma (late Albian), while a bentonite near the base of the overlying Seabee Formation was deposited at 98.2 ± 0.8 Ma, in the early Cenomanian. The two ages bracket a major flooding surface at the base of the Seabee Formation near Umiat, Alaska, placing it near the Albian-Cenomanian boundary (100.5 Ma). Several hundred feet up-section, the non-marine Tuluvak Formation contains bentonites with 40Ar/39Ar ages of 96.7 ± 0.7 to 94.2 ± 0.9 Ma (Cenomanian), several million years older than previously published K–Ar ages and biostratigraphic constraints suggest.Major and trace element geochemistry of a sub-sample of six bentonites from petroleum exploration wells at Umiat show a range in composition from andesite to rhyolite, with a continental arc source. The bentonites become more felsic from the late Albian (∼102 Ma) to late Cenomanian (∼94 Ma). A likely source for the bentonites is the Okhotsk-Chukotka Volcanic Belt (OCVB) of eastern Siberia, a continental arc which became active in the Albian and experienced episodes of effusivity throughout the Late Cretaceous. Chronostratigraphically anomalous 40Ar/39Ar ages coincide with peaks of magmatic activity in the OCVB, suggesting that these anomalously old ages may be due to magmatic contribution of xenocrysts or recycling of detrital minerals from older volcanic events. An alternative explanation for the chronostratigraphically anomalous ages is mixing of bentonites with detrital sediment derived from unroofing and erosion of metamorphic rocks in the Brooks Range, Herald Arch, and Chukotka throughout the mid to Late Cretaceous.

Dynamics of a recovering Arctic bird population: the importance of climate, density dependence, and site quality.

Intrinsic and extrinsic factors affect vital rates and population-level processes, and understanding these factors is paramount to devising successful management plans for wildlife species. For example, birds time migration in response, in part, to local and broadscale climate fluctuations to initiate breeding upon arrival to nesting territories, and prolonged inclement weather early in the breeding season can inhibit egg-laying and reduce productivity. Also, density-dependent regulation occurs in raptor populations, as territory size is related to resource availability. Arctic Peregrine Falcons (Falco peregrinus tundrius; hereafter Arctic peregrine) have a limited and northern breeding distribution, including the Colville River Special Area (CRSA) in the National Petroleum Reserve-Alaska, USA. We quantified influences of climate, topography, nest productivity, prey habitat, density dependence, and interspecific competition affecting Arctic peregrines in the CRSA by applying the Dail-Madsen model to estimate abundance and vital rates of adults on nesting cliffs from 1981 through 2002. Arctic peregrine abundance increased throughout the 1980s, which spanned the population's recovery from DDT-induced reproductive failure, until exhibiting a stationary trend in the 1990s. Apparent survival rate (i.e., emigration; death) was negatively correlated with the number of adult Arctic peregrines on the cliff the previous year, suggesting effects of density-dependent population regulation. Apparent survival and arrival rates (i.e., immigration; recruitment) were higher during years with earlier snowmelt and milder winters, and apparent survival was positively correlated with nesting season maximum daily temperature. Arrival rate was positively correlated with average Arctic peregrine productivity along a cliff segment from the previous year and initial abundance was positively correlated with cliff height. Higher cliffs with documented higher productivity (presumably indicative of higher-quality habitat), are a priority for continued protection from potential nearby development and disturbance to minimize population-level impacts. Climate change. may affect Arctic peregrines in multiple ways, including through access to more snow-free nest sites and a lengthened breeding season that may increase likelihood of nest success. Our work provides insight into factors affecting a population during and after recovery, and demonstrates how the Dail-Madsen model can be used for any unmarked population with multiple years of abundance data collected through repeated surveys.

Nest visits and capture events affect breeding success of Yellow-billed and Pacific loons

ABSTRACT Accurate estimates of breeding success are essential for understanding population dynamics and for managing populations. Unfortunately, research activities to collect these data can negatively impact the breeding success of the study species and bias estimates of breeding success. Despite the potential for negative impacts, few studies have documented the effect of capturing incubating adults on nest survival or compared nest survival following different capture methods. In this study we evaluate the impacts of investigator disturbance associated with captures and nest visits on nest survival of Yellow-billed Loons (Gavia adamsii) and Pacific Loons (Gavia pacifica) in the National Petroleum Reserve-Alaska (NPR-A), an area of conservation concern, in 2011–2013. In an effort to reduce capture-related nest failures, we developed a new suspended dive net technique to catch territorial aquatic birds while off their nests. We then compared nest survival following suspended dive net captures to bow-net ...

Alaskan North Slope Legacy Wells: Case Study

ABSTRACT Various State of Alaska agencies, including the Alaska Department of Environmental Conservation (ADEC), are currently investigating 136 legacy wells within the National Petroleum Reserve-Alaska (NPR-A) and surrounding lands. These legacy wells were drilled between 1944 and 1981 by federal agencies, including the United States Navy and United States Geological Survey, to explore oil reserve potential and to develop drilling techniques for Alaska's arctic. In 2004, 2010 and 2013 the Bureau of Land Management released preliminary studies describing potential environmental risks at each site. Many wells include historic reserve pits, flare pits, crude and diesel oil releases, and discarded solid waste. Tundra damage and potential residual contamination are of great concern. Due to their remote locations, information on the current status of waste is limited. Regulatory agencies are developing a cleanup plan that is appropriate for their remote, Arctic environment.