Icebreaking Drillship for Offshore Exploratory Drilling in the Arctic

The ‘Frontier Arctic’ offshore has been explored on and off since the 1970s, driven by oil price and areas open for leasing or licensing. While a widespread, future return is questionable, operators contemplating a return can benefit from past experience. Insight and perspective are provided on the technical and non-technical challenges and impact on the business challenge. Actions and opportunities to change the overall cost and non-technical business risk dynamic are discussed. ‘Frontier Arctic’ oil and gas resources have characteristics of 1) being located outboard of established offshore regions of oil and gas exploration and development, 2) having physical attributes of water depth and ice conditions that require the use of specialized equipment or measures to safely and cost effectively drill, and 3) having non-technical business risks with the potential for high business consequences. This loose definition includes much of the Alaskan Arctic, the Canadian Beaufort Sea, Greenland, the far northern Barents Sea, and much of the Russian shelf. The technical and non-technical issues associated with exploration drilling in these regions are well-established, but not necessarily well-integrated. ‘Frontier Arctic’ exploration drilling can be safely, responsibly, and reliably executed. The principal challenges are cost to address both routine operations and emergency response preparedness and and non-technical business risk. The required solutions to address these challenges and business risks lead to a layering of complexity and cost that increase exploration drilling costs multifold over competing oil and gas investment opportunities and require significant and sustained commitments of financial, organizational and people resources to achieve business success. Furthermore, ‘Frontier Arctic’ opportunities cannot be turned on at will and require significant planning and preparation and associated lead time. Interest in ‘Frontier Arctic’ exploration may be rekindled in the future depending upon commodity prices; however, the ability to make material cost changes are limited due to the nature of the technical challenge; and the "Frontier Arctic’ will likely remain a target for environmental activism. Furthermore, exploration drilling would need to take place now or in the reasonably near future if ‘Frontier Arctic’ resources are to have a chance of contributing to a future oil or gas supply shortfall. Notwithstanding, Arctic offshore exploration can be expected to continue in regions where cost and business risk can be managed such as the southern Barents Sea and nearshore Alaska Beaufort Sea region.

Connecting subsistence harvest and marine ecology: A cluster analysis of communities by fishing and hunting patterns

Regional crustal shortening in northern Yukon and northeastern Alaska occurred episodically from the latest Cretaceous to the late Miocene, with a major culmination occurring in the Paleocene to middle Eocene, and a secondary culmination in the late Miocene. Structural trends are predominantly north to northeastward in northern Yukon and adjacent east-central Alaska, and generally east-west along the Brooks Range. The early Tertiary trend is strongly arcuate in the Beaufort fold belt and adjacent onshore areas. The continuity of structures southward from the Beaufort Sea region through northern Yukon and east-central Alaska supports the interpretation that the structures north of 65°N form a single orogenic entity. The Beaufort Sea region is 1000 km from the nearest plate margin. Northward shortening across Arctic Alaska and the northern Canadian cordillera reflects the convergent component of Kula (later, Pacific)–North America interactions throughout the Tertiary. North-to northeast-trending structures of latest Cretaceous to early Tertiary age in northern Yukon and east-central Alaska accommodate shortening of 180–240 km, and reflect Eurasia–North America convergence. The strongly arcuate offshore Beaufort fold belt and similar structures in adjacent northernmost Yukon and northeast Alaska were formed by the complex interplay of three factors: shortening of northern Yukon between Arctic Alaska and the craton to produce a north-trending orogenic welt; northward displacements propagated from the Kula plate margin; and local boundary conditions imposed by lithology and crustal structure, which aided lateral escape of the deforming supracrustal succession northward into the Beaufort Sea. In central Alaska, any kinematic linkage between the Kaltag fault in the west and the Tintina fault of the northern cordillera is more complex than was previously assumed. A new regional tectonic reconstruction of northern Yukon-Alaska quantifies the tectonic shortening in central Alaska south of the Kaltag and Tintina faults in an area where tectonic shortening is difficult to quantify due to complex geology. Complex deformation accommodated by folding, thrust and strike-slip faulting, and/or tectonic rotations accounts for an estimated 460 km of crustal shortening, approximately equivalent in magnitude to the total Tintina fault displacement of at least 450 km. The foreland of the Brooks Range, the Beaufort fold belt, and the northern cordillera contain proven petroleum basins. This regional synthesis validates a model of orogenic shortening for the Beaufort fold belt and provides a unifying tectonic setting for oil and gas plays throughout the region. The latest Cretaceous–Tertiary structural evolution of the Brooks Range, Beaufort, and northern Yukon fold belts is a case study of the temporally and kinematically complex far-field deformation arising from the convergence of four major tectonic plates.

Decline of the Arctic summer minimum sea ice extent is characterized by large expanses of open water in the Siberian, Laptev, Chukchi, and Beaufort Seas, and introduces large fetch distances in the Arctic Ocean. Long waves can propagate deep into the pack ice, thereby causing flexural swell and failure of the sea ice. This process shifts the floe size diameter distribution smaller, increases floe surface area, and thereby affects sea ice dynamic and thermodynamic processes. The results of Radarsat-2 imagery analysis show that a flexural fracture event which occurred in the Beaufort Sea region on 6 September 2009 affected ∼40,000 km2. Open water fractional area in the area affected initially decreased from 3.7% to 2.7%, but later increased to ∼20% following wind-forced divergence of the ice pack. Energy available for lateral melting was assessed by estimating the change in energy entrainment from longwave and shortwave radiation in the mixed-layer of the ocean following flexural fracture. 11.54 MJ m−2 of additional energy for lateral melting of ice floes was identified in affected areas. The impact of this process in future Arctic sea ice melt seasons was assessed using estimations of earlier occurrences of fracture during the melt season, and is discussed in context with ocean heat fluxes, atmospheric mixing of the ocean mixed layer, and declining sea ice cover. We conclude that this process is an important positive feedback to Arctic sea ice loss, and timing of initiation is critical in how it affects sea ice thermodynamic and dynamic processes.

Chapter 7 - Polar Bear

Abstract. Changes in the mean sea ice thickness and concentration in the Arctic are well known. However, quantitative information about changes in the ice thickness distribution and the composition of the pack ice is lacking. In this paper we determine the ice draft distributions, mean and modal thicknesses, and their regional and seasonal variability in the Arctic for the time period 1975–2000. We compare characteristics of the Arctic pack ice for the years 1975–1987 and 1988–2000. These periods represent different large-scale atmospheric circulation modes and sea ice circulation patterns, most evident in clearly weaker Beaufort Gyre and stronger as well as westward shifted Transpolar Drift during the later period. The comparison of these two periods reveals that the peak of sea ice draft distributions has narrowed and shifted toward thinner ice, with reductions in both mean and modal ice draft. These noticeable changes are attributed to the loss of thick, mostly deformed ice. Springtime, loss of ice volume with draft greater than 5 m exceeds 35 % in all regions except the Nansen Basin, with as much as 45 % or more at the North Pole and in the Eastern Arctic. Autumn volume reduction, mostly of deformed ice, exceeds 40 % in the Canada Basin only, but is above 30 % also in the Beaufort and Chukchi Seas. During the later period, the volume of ice category consisting thin, mostly level first-year ice, is clearly larger than during the former period, especially in the spring. In the Beaufort Sea region, changes in the composition of ice cover have resulted in a shift of modal draft from level multiyear ice draft range to values of level first-year ice. The regional and seasonal variability of sea ice draft has decreased, since the thinning has been most pronounced in regions with the thickest pack ice (the Western Arctic), and during the spring (0.6–0.8 m per decade).

On 9 September 2012, Noble Discoverer, a Royal Dutch Shell’s drill ship, began drilling in the Chukchi Sea 70 miles off the Alaska coast, signifying the return of active offshore exploration in the US Arctic (Broder, 2012a). Another Shell drill vessel, Kulluk, commenced drilling in the Beaufort Sea on 3 October 2012 (Shell, 2013). Yet Shell’s foray into the US Arctic offshore was brief — the exploratory drilling in the Chukchi Sea lasted just over a week and in the Beaufort Sea for three weeks (Krauss, 2012). Shell’s 2012 US Arctic campaign was also unproductive. After spending over US$4.5 billion, Shell had only two top holes to show for it at the end of the season.1 The main reason why Shell was not allowed to drill into the hydrocarbon-bearing reservoir is because it was not authorized to do so by the US government. The drilling permits issued by the Bureau of Safety and Environmental Enforcement (BSEE)2 were limited to drilling top holes because Shell failed to deploy the Arctic Containment System fully tested by BSEE before commencing drilling activities (DOI, 2013, p. 16).

Miscellaneous Publication 167, Map and database of exploration drilling targets categorized by play type, North Slope and offshore Arctic Alaska, presents a compilation of discovery well and production data for oil and gas wells throughout the North Slope and offshore Arctic Alaska. Since exploration drilling began on the North Slope of Alaska in 1944, numerous oil and gas accumulations have been discovered and 18 billion barrels of liquid hydrocarbons have been produced from North Alaska through 2018. Wells have targeted five main play types: Ellesmerian clastics and carbonates (Kekiktuk, Lisburne, Ivishak, Shublik, and Sag River), Jurassic shoreface sands (Barrow, Simpson, Kugrua, Nechelik, Nuiqsut, and Alpine), Cretaceous rift sands (Walakpa, Kuparuk, Put River, Kemik, and Thomson), Brookian turbidites (Torok, Seabee, and Canning), and Brookian topsets (Nanushuk, Tuluvak, Schrader Bluff, West Sak, Ugnu, Prince Creek, and Sagavanirktok). A sixth category called 'Other' includes the remaining targets (e.g., basement, methane hydrates, and coalbed methane). This comprehensive study documents the drilling target by play type from public domain sources for 548 exploration wells on the North Slope and adjacent offshore areas in the Beaufort Sea and Chukchi Sea. The discovery well and production data for each producing pool are integrated into the study. All files are available from the DGGS website: http://doi.org/10.14509/30579.

Northern Development and Technology Assessment Systems; A Study of Petroleum Development Programs in the Mackenzie Delta - Beaufort Sea Region and the Arctic Islands, by Robert F. Keith, David M. Fischer, Colin E. De'Ath, Edward J. Farkas, George R. Franc

In the Beaufort Sea, observations of extreme draft sea ice features havebeen identified from upward looking sonar (ULS) datasets spanning severalyears. Using analysis methods from extreme value theory, the estimated 100-yearreturn values of the maximum ice draft have been derived. In addition, theapplicability of these statistical techniques to the Northeast Greenland iceregime is examined using one year of ULS data at two locations from 2008 to2009. The methods have been developed for the Beaufort Sea region andsubsequently, further refined for use in estimating extreme ice hazards offNortheast Greenland. These estimates provide inputs to the design of offshoreplatforms and ships in support of oil and gas activities in these ice-infestedwaters. Previous studies in the Canadian Beaufort Sea derived an empirical upperlimit on the maximum sea ice thickness resulting from deformation processesbased on the relationship of maximum ice thickness as a function ofsimultaneous values of undeformed ice thickness. Using the more extensive ULSice keel data sets now available, these methods were re-evaluated and updated. Similar analyses were carried out on ice thickness measurements obtained offNortheast Greenland which reveal distinct differences in the ice regime ofthese two geographical areas. Improvements to extremal value statistical analysis methods for longrecurrence intervals of 100 years for ice draft (D100) are based on the threeparameter Weibull distribution which has been optimized for application to verylarge sea ice keels using a peak over threshold selection approach. Theseresults were compared to the maximum draft limit and undeformed ice thicknessrelationship. We developed techniques to refine at a high resolution the lowerthreshold on maximum draft and examine the implications of this filtering onD100. This is an important consideration as selecting the lower maximum draftthreshold is a balance between retaining enough observations to ensurestatistical robustness and sampling only the extreme tail of the maximum draftdistribution. Methods for performing these statistical analyses arepresented.

The Beaufort Gyre (BG) typically rotates anticyclonically and exerts an important control on Arctic Sea ice dynamics. Previous studies have shown reversals in the BG to rotate cyclonically during summer months and, in recent decades, throughout the annual cycle. In this investigation, we explore the synoptic climatology of atmospheric forcing and its relationship to sea ice motion and BG reversals. A catalog of daily synoptic weather types is generated for the Beaufort Sea Region covering the period 1979 to 2006 using NCEP/NCAR reanalysis mean sea level pressure data, principle components, and k‐means cluster analyses. Mean synoptic type frequency, persistence, and duration values are calculated for each synoptic type and contrasted between the summer and winter seasons. Daily synoptic types are linked to changes in sea ice vorticity by using correlation analysis on lagged sea ice vorticity data. Lag correlations are found between synoptic types and sea ice vorticity smoothed over a 12‐week running mean and show that cyclonic types, which promote southerly or easterly atmospheric circulation over the southern Beaufort Sea, commonly precede summer reversals. Furthermore, significant seasonal within‐type variability in sea ice vorticity is detected within the synoptic types illustrating the importance of seasonal variability on these processes.

Tarsiut Island is the first caisson retained island that has been built for drilling operations in the Arctic Offshore. Because of its novelty, a real time monitoring program involving the predicted and observed performance of the island under ice loading was established to ensure safe and efficientdri11ing operations and to satisfy government requirements. To accomplish this program, an extensive state of the art instrumentation, data acquisition and monitoring system was developed and utilized to collect ice action and island response information. The data was used in real time to assess island stability and provide an alert warning to drilling personnel. The alert levels were related to drilling activities to ensure the integrity of the operation. This paper describes the methodology, procedures and experiences associated with the Tarsiut winter monitoring program. INTRODUCTION Although many artificial islands have been built in the Canadian Beaufort Sea (De Jong and Bruce, 1978), the Tarsiut structure represents a significant new extension to Arctic drilling technology. This island, constructed by Canadian Marine Drilling under contract to Gulf Canada Resources, was the first caisson retained island used for exploratory drilling in ice infested waters (Stenning and Fitzpatrick, 1983). During the winter, spring and summer of 1982, Gulf Canada as operator for the Tarsiut group*, dri11ed the Tarsiut N-44 and N-44A wells from the island as a part of its Beaufort Sea exploration program. The N-44 well, drilled on the same geological structure as the Tarsiut A-25 discovery of 1980, yielded 556 m / day (3500 bbl /day) while the subsequent N-44A delineation well, side tracked from the same well bore, was less prolific yielding 346 m3/day (2175 bbls/day). In addition to the novel use of caisson technology to reduce the fill requirements for island construction, the Tarsiut structure was located in 21 m of water making it the deepest artificial island ever built in the Beaufort Sea. The island was al so located in an area where dynamic ice motion was expected for at least part of the winter season. Tarsiut was designed on the basis of theoretical analyses, model tests and full scale experience at other islands (Croasdale and Marcellus, 1978). The design work indicated that under expected ice conditions and loadings, there should be no hazard to the island from the stability or operational viewpoint. However, because Tarsiut was novel, there was a finite probability that the ice conditions might be different than expected or that some interactions not predicted by experience, theory or model tests might occur. This was recognized by Gulf Canada, its partners and the Canadian regulatory agencies and procedures were implemented to ensure that the effects of the ice environment on the stability and operations from Tarsiut Island were known or could be anticipated at all times.

Spatial distribution and risk assessment of metal(loid)s in marine sediments in the Arctic Ocean and Bering Sea

Sparse stations and serious measuring problems hamper analyses of climatic conditions in the Arctic. This paper presents a discussion of measuring problems in the Arctic and gives an overview of observed past and projected future climate variations in Svalbard and Jan Mayen. Novel analyses of temperature conditions during precipitation and trends in fractions of solid/liquid precipitation at the Arctic weather stations are also outlined. Analyses based on combined and homogenized series from the regular weather stations in the region indicate that the measured annual precipitation has increased by more than 2.5% per decade since the measurements started in the beginning of the 20th century. The annual temperature has increased in Svalbard and Jan Mayen during the latest decades, but the present level is still lower than in the 1930s. Downscaled scenarios for Svalbard Airport indicate a further increase in temperature and precipitation. Analyses based on observations of precipitation types at the regular weather stations demonstrate that the annual fraction of solid precipitation has decreased at all stations during the latest decades. The reduced fraction of solid precipitation implies that the undercatch of the precipitation gauges is reduced. Consequently, part of the observed increase in the annual precipitation is fictitious and is due to a larger part of the "true" precipitation being caught by the gauges. With continued warming in the region, this virtual increase will be measured in addition to an eventual real increase.

The clay-sized (< 2 μm) fraction of the silty and arenaceous lutites constituting CESAR cores 14 and 103 (Alpha Ridge, central Arctic Ocean) is composed predominantly of mica (40–60%), with subequal percentages (10–20%) of kaolinite and chlorite and lesser amounts (< 5%) of smectite, quartz, plagioclase, and potassium feldspar. Calcite and dolomite also occur, but only intermittently in the upper 1.2 m; dissolution is probably responsible for their absence in other units. The silty lutites have a constant mineralogy throughout the 4.5 m long (~ 4.25 Ma) section, whereas some of the arenaceous intervals in the upper 2.1 m have markedly higher amounts of kaolinite, calcite, dolomite, and, to a lesser extent, smectite. The silty lutites were most likely derived from the Beaufort Sea shelf during nonglacial periods, whereas the distinctive components in the sandy layers suggest that they were transported from the Canadian Arctic Islands and Greenland by glacial ice. The absence of kaolinite peaks in the lower half of the core implies that the western Arctic Islands were not glaciated prior to 2.1 Ma, a conclusion supporting previous findings that the climate of the Arctic was warmer in the Pliocene.