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5 Future Oi' and Gas Activities The directive to the Committee on Cumulative Environ- mental Effects of Oil and Gas Activities on Alaska's North Slope included assessing the likely future cumulative effects of industrial activities that have occurred on the North Slope and the cumulative effects of future industrial activities. All projections of activities and the accumulation of their effects are uncertain because many factors, some of which are highly unpredictable, will influence the location and extent of ex- ploration for and extraction of oil and gas on the North Slope. For example, extraction and marketing of oil depend on the price of oil, which in turn depends on the ability of the Orga- nization of Petroleum Exporting Countries (OPEC) to main- tain high prices for oil on the world market. Wars or terrorist activities could dramatically alter all industrial activities on the North Slope. Nonetheless, without a plausible scenario the commit- tee could not make substantial progress in predicting cumu- lative effects on the physical and biologic systems of the North Slope. We therefore evaluated the consequences of a development scenario that assumes a continuing favorable market price for oil and "normal" international relations dur- ing the next several decades. Such a scenario is plausible even though the probability of its occurrence cannot be determined. PLAUSIBLE SCENARIO Even if prices and political stability were to continue to favor exploration and extraction of North Slope oil and gas, many variables bear on the amount of activity and the suc- cess of future exploration and development: land availabil- ity, the regulatory environment, pricing, technology, explo- ration concepts, competition, and infrastructure. The committee's scenario is based on the way the petro- leum industry operates now, and it assumes a continuation of trends, as indicated by recent activities and the actions undertaken or supported by the key federal and state over- s 7 sight agencies. The 1002 Area of the Arctic National Wild- life Refuge (see Figure 4-1) is not analyzed in detail because exploration there is currently prohibited. However, the area is included as a possible additional and potentially signifi- cant component of the recoverable oil reserves on the North Slope in case exploration there is approved by Congress. The scenario has a list of important assumptions: Oil prices will remain high enough to support contin- ued exploration and development. Climate change will not be so great during the next 50 years as to render current exploration methods obsolete or foreclose modifications, such as use of Rolligons and new drilling platforms. All new exploration and development activities will use technologies at least as good as those in use at Alpine. Offshore exploration (and probable extraction) will continue, but at a slower pace, along the Beaufort Sea coast from Point Barrow to Flaxman Island and possibly eastward to the Canadian border. Onshore exploration (and probable extraction) will continue both southward into the foothills of the Brooks Range and westward well into the National Petroleum Reserve-Alaska. Gas will become a significant component of explora- tion and development activity, and a gas pipeline will be built. The number of exploration companies, especially with gas interests, will expand and competition will increase. The committee's projection assumes significant new discoveries and developments and a gradual decline in out- put from older oil fields. This in turn is likely to influence development of satellite fields. We assume there will be sig- nificant oil discoveries in each of the exploration sub- provinces, with the possible exception of the southern area of the National Petroleum Reserve-Alaska, where gas de- posits are more likely to be recoverable. We consider the

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52 probable exploration and development activities from the present to 2050. Exploration Provinces Our forecast separates potential activity in three major operating provinces that correspond to the jurisdictional framework within which future developments are likely: the state and native lands of the Colville-Canning Province, the Beaufort Sea, and the federal lands of the National Petro- leum Reserve-Alaska. These subdivisions are under the ju- risdiction of different regulatory agencies, and they have dif- ferent leasing schedules, regulatory regimes, infrastructure needs, and resource potential. The Beaufort Sea is consid- ered as two subunits, the federal outer continental shelf (OCS) and the shallower state nearshore area. The National Petroleum Reserve-Alaska and Colville-Canning are subdi- vided into gas- and oil-prone subprovinces. Three related sets of units of measure are often used in discussions about oil reserve or resource estimates: original oil in place (OOIP), technically recoverable reserve (TRR), and economically recoverable reserve (ERR). Gas reserves are treated similarly. OOIP estimates the volume in a reser- voir or reservoirs before production starts. It does not repre- sent the quantity that can be produced from the field. OOIP at Prudhoe Bay was approximately 23 billion barrels (bbl). (A barrel is 42 U.S. gallons, or 159 L). TRR is the volume of oil or gas that is recoverable independent of price. ERR, that portion of TRR that it is feasible to recover, is sensitive to price and technology. The current ERR estimate for the Prudhoe Bay field is 13 billion bbl. Under ideal conditions ERR approaches TRR, but rarely does a reservoir yield an ERR that exceeds 0.5 times that area's OOIP. It is important to distinguish such estimates when read- ing published information about oil and gas reserves. The numbers that industry releases or discusses for new discov- eries or existing fields generally are ERR values. The federal agencies and other groups that perform public domain as- sessment of oil and gas reserves, as in the Arctic National Wildlife Refuge and the National Petroleum Reserve-Alaska, generally present their results as TRR. For example, in the 2002 appraisal of the National Petroleum Reserve-Alaska, the USGS provided a mean reserve estimate of 9.3 billion bbl of TRR. They then may give an estimate, as a function of assumed oil price ranges, of ERR. In the 2002 National Pe- troleum Reserve-Alaska appraisal ERR was estimated to range between 1.3 and 5.6 billion bbl of oil over a range of market prices between $22.00 and $30.00 per barrel. Once production has been established in an area, with the discovery of a large commercial accumulation of oil or gas, other adjacent, nreviousiv technicaliv recoverahle hut . .. ~ . .. .. . . . . . . . . uneconomic, small accumulations become economic despite a relatively low oil or gas market price. This is because the investment in the necessary production and transportation infrastructure has been justified by the discovery of the large CUMULATIVE EFFECTS OF ALASKA NORTH SLOPE OIL AND GAS field. Examples are the Midnight Sun oil field north of Prudhoe Bay and the satellites north and south of Alpine. The Midnight Sun field is a 20- to 40-million-barrel field that would have no stand-alone economic value. The pres- ence of the Prudhoe Bay field and its infrastructure turns several millions of barrels of technically recoverable reserves into economically recoverable reserves. The same holds true for the Alpine field and its satellites. Much of the current activity in and near the major North Slope fields is related to the development of these small accumulations. In many of the following sections, two sets of reserve numbers are given. The intent is to provide TRR estimates made by various groups or agencies for these exploration provinces and then to present possible volumes of ERR ad- ditions for comparison with the produced volumes and re- maining known reserves in the discovered fields. ERR esti- mates are based on the scenario assumptions presented above and reflect OOIP or TRR volumes, or both. Reliable estimates for the remaining potential for oil and gas on the North Slope are not available because of a lack of resource evaluations based on current geological knowledge. One recent estimate (Coleman et al.2001) placed future TRR volumes for the Brooks-Colville system of the North Slope at 14 billion bbl of oil and 32.8 trillion cubic feet of gas (TCFG). The information available indicates that those esti- mates include the Arctic National Wildlife Refuge. They do not allow for significant reserves in the non-refuge portions of the North Slope, which include all of the National Petro- leum Reserve-Alaska, the currently underexplored and non- productive portions of the Colville-Canning Province, and the Beaufort Sea. The numbers are probably conservative given recent discoveries in and near the National Petroleum Reserve-Alaska and the size of the U.S. Geological Survey (USGS) estimates for the Arctic National Wildlife Refuge. Unpublished, proprietary estimations for the entire North Slope and the state waters of the Beaufort Sea range from mean undiscovered TRR of 12.6 billion bbl of oil and 54.1 TCFG (Magoon 1994) to a TRR of 18 billion bbl of oil, exclusive of Arctic National Wildlife Refuge reserves. The disparity in those numbers generates confusion about the magnitude of the remaining undiscovered reserves on the North Slope and the adjacent Beaufort Sea. (Note that the numbers do not include the federal OCS portion of the Beau- fort Sea.) Gas has frequently been ignored or downplayed in the resource assessment process, but it has gained new em- phasis since the construction of a gas pipeline has garnered renewed support. The last thorough assessments of those areas, exclusive of the Arctic National Wildlife Refuge, were completed in 1978 and 1980, and USGS is currently reevaluating the esti- mates. Resource evaluations for the National Petroleum Reserve-Alaska were compiled in May 2002 (Bird and Houseknecht 2002~. For the rest of the North Slope, they are expected in late 2003 or early 2004 (K. J. Bird, USGS, per- sonal communication, 2001~.

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FUTURE OIL AND GAS ACTIVITIES Colville-Canning Province This area includes all lands between the Colville and Canning rivers, from the Beaufort Sea south to the north- ern limits of the Gates of the Arctic National Park and Arctic National Wildlife Refuge. The bulk of the area is state owned, but the Arctic Slone Regional Cornoration (ASRC) controls nearly 1.2 million hectares (ha, 3 mil- lion acres) in the Brooks Range foothills. Lease sales have been held in the area since 1958, with 4 federal sales and 28 state sales. Hundreds of wells have been drilled, most of them in the major fields of the northern portion of the area; ERR of 17 billion to 18 billion bbl of oil and more than 35 TCFG have been found. The major oil discoveries include the Prudhoe Bay, Kuparuk, Endicott, Point McIntire, and Alpine fields as well as numerous small satellite fields. Prudhoe Bay and Point Thomson are the sites of the principal gas accumulations. All of these fields are in the northern area, on or near the Barrow Arch. Far- ther to the south the source rocks and reservoirs are deeply buried and are generally too mature to contain oil. This southern gas-prone region is called the Brooks Range foothills belt. Based on the presence of 35 TCFG in the area of the developed and developing fields, it is obvious that the oil-prone area also has significant gas resources. The converse is not necessarily true. The oil potential of the foothills belt could be modest at best. Northern Colville-Canning This area, between Canning and Colville rivers, extends south from the Beaufort Sea coast to approximately 69 45' N latitude and has been the focus of most of the exploratory drilling and oil development on the North Slope since 1969. All of the onshore producing oil fields are located here. The area is expected to continue to be one of the most active regions of the North Slope, at least for the near-term, as major producers add production through the discovery of new medium-sized oil accumulations and the development of satellite fields. If the economic indicators continue to be favorable, gas pipeline and gas-producing facilities could be brought online by 2010. If so, gas exploration would become routine. The expansion of the gas-producing and gathering system would continue into the early 2020s. Most of the at- tractive area would be leased by 2010 and fully developed by 2030. The existing fields and infrastructure should con- tinue be the backbone of North Slope production, either directly or indirectly, by supplying the facilities to allow nearby, otherwise uneconomic, oil and gas accumulations to be developed. If so, oil production could continue well into the second quarter of the twenty-first century; gas produc- tion could go until 2040-2050. Future reserve additions should be approximately 2.5 billion to 3 billion bbl of oil with the possibility of two to three times that quantity if new technologies result in increased recovery from the West Sak 53 and Ugnu heavy oil reservoirs. The potential for additions to the gas reserve base is 10-15 TCFG. Brooks Range Foothills Belt The Brooks Range foothills belt extends south from ap- proximately 69 45' N to the northern boundary of the Arctic National Wildlife Refuge and Gates of the Arctic National Park and lies between the refuge and National Petroleum Reserve-Alaska. ASRC lands are included with the state area 1- . Discussion. The total area is about 4 million ha (9.8 million acres), and ASRC owns or otherwise controls a little less than one- third of the area. Until the 2001 North Slope foothills sale, most of the state area had not been leased; however, large tracts were leased in the late 1950s and early 1960s by the federal government, before conveyance to the state. About 405,000 ha (about 1 million acres) was leased in the May 2001 state sale. Over the past 30 years, the ASRC has ac- tively sought to have its lands explored, and it has assigned exclusive exploration rights to several companies. About 40 wells have been drilled in this subprovince, including those drilled in the Kavik and Kemik gas fields, 8 of them on Native lands. Although the area is gas-prone, there has been no market for gas, and only one well has been drilled in the area in the past 20 years. With the possibility of a gas pipeline and the discovery of immature to early-mature oil-prone source rocks, interest in the area has increased. Exploration and production operations require large quantities of gravel and water. The foothills belt has few lakes to supply water for ice roads or pads or for production and waste disposal. As a result, the extent to which ice will supersede gravel is unknown. Rivers could be the preferred water sources in some places. Produced water might be suf- ficient for most waste disposal and production needs. River gravel also is scarce, and it could be necessary to mine up- land areas to supply gravel for production facilities and their associated airstrips and roads. Existing exploration and development technologies would be used extensively to provide the infrastructure and gas pipeline system. Acquisition of seismic data is under way and will continue into the foreseeable future. A drilling rig is under contract to one leaseholder, and exploration drill- ing could begin soon. The foothills area is expected to be a major source of gas, and it is reasonable to expect at least five significant fields would be established. Gas develop- ment could be under way by the time a trans-Alaska gas pipeline is completed, and production could begin as early as 2010. Gas production should continue into the 2040s. These gas fields will have small footprints, but the ac- companying pipeline system could easily extend 161 km (100 mi) or more to the west from the pipeline. Much if not all of the gas pipeline system probably would be buried. Based on the size of surface geological features (exposed anticlines), an individual gas accumulation could have 10-

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54 15 TCFG. Technically recoverable reserves are expected to be at least 25 TCFG. Oil production and economically recoverable reserves in the area are expected to be modest by North Slope stan- dards and secondary in importance to gas. They would most probably be found in fields of 300 million to 400 million bbl of oil or less and be developed much later, possibly not until after 2020. Additions to oil reserves are expected to be about 1 billion bbl. A recent paper, presented by Anadarko Petroleum (Nelson 2002), suggests that the foothills area technically recoverable reserves are 0.5 billion to 2.5 billion bbl of oil and 20-40 TCFG. Beaufort Sea The Beaufort Sea area consists of federal and state lands off shore from the seaward extension of the Alaska-Yukon Territory border west to a line extended north from Point Barrow. The federal and state lands are administered through different leasing programs, and the distance from onshore facilities and the differences in water depth dictate that we address the two areas separately. Federal Outer Continental Shelf The federal OCS area lies seaward of the three-mile limit, or extensions of this limit, seaward of the offshore islands and bay mouths; the OCS is administered by the Minerals Management Service (MMS) of the Department of the Interior. Thirty exploration wells have been drilled on federal or joint federal-state leases. Eleven were deemed ca- pable of production and five were termed significant discov- eries by the MMS. Oil has been the focus of all exploration to date, but if a gas pipeline were built, gas could be the target of exploration and development. It is probable that there will be a short-term decrease in exploration and consequently little development or produc- tion activity in the federal portion of the Beaufort Sea other than at Northstar. An exploration well could be drilled on the McCovey prospect during the 2003 drilling season. Leasing and drilling will be below historic levels for the next 10-15 years, perhaps until the early 2020s. Individual ERR discoveries for oil can be anticipated to range from 100 million to 2 billion bbl. Northstar is at the lower end of that range. Prospects like McCovey and Kuvlum could reach or exceed a billion barrels. Individual gas fields could range from a few hundred-billion cubic feet to a few trillion cubic feet of gas. These finds could be oil- associated gas, as at Prudhoe Bay, or pure gas accumula- tions, as at the Barrow and Kavik gas fields. ERR additions of 2.5 billion bbl of oil and 15 TCFG are possible. Over the long-term, activity could increase if nearby onshore and nearshore state lands are explored and devel- oped. For example, if Point Thomson were developed, it CUMULATIVE EFFECTS OF ALASKA NORTH SLOPE OIL AND GAS might be more feasible to consider development of other dis- coveries in that area. The additional 15-20 years also will provide time to more fully research and implement technolo- gies that would reduce the environmental consequences of Beaufort Sea exploration and production, especially under conditions of broken ice. By the second quarter of the twenty-first century, exploration could increase to levels seen in the middle 1980s and early 1990s. If new technologies were developed, the life of the facilities at Prudhoe Bay and other major fields would be prolonged, as would use of the Trans-Alaska Pipeline. State Nearshore Labels Leasing and exploration began in 1979 on state lands that lie within the three-mile limit. Significant discoveries have been made at Endicott, Niakuk, West Beach, Point McIntire, and Midnight Sun. The undeveloped Flaxman Is- land discovery lies just west of the mouth of the Canning River and offshore from Point Thomson. Exploration for oil has dominated the effort, but gas could be a target of future exploration and development. The state Beaufort Sea lands are likely to continue to be desirable holdings, and leases will be retained and evaluated as promptly as circumstances and priorities permit. The like- lihood of leasing significant new areas probably depends on the eventual availability of the deferred tracts lying offshore from the National Petroleum Reserve-Alaska and in the Arc- tic National Wildlife Refuge. The amount of activity should remain constant for the next 20-25 years and then gradually decline as the oil fields are depleted over the two to three decades thereafter. The gas fields will, in large part, be found later in the exploration cycle and would be brought to pro- duction more slowly. The life of the gas fields can be ex- pected to extend beyond that of the oil fields. Over the next 25-30 years, exploration could add 1 billion bbl ERR of oil and modest amounts of natural gas (5-10 TCFG). National Petroleum Reserve-Alaska The National Petroleum Reserve-Alaska is administered by the Bureau of Land Management (BLM), with technical assistance in resource evaluation and lease sales manage- ment from the USGS and MMS, respectively. Before 1999, the only National Petroleum Reserve-Alaska lease sales were held in the early 1980s (BLM, unpublished data, l990~. The impetus for the 1999 sale was the discovery of the Alpine oil field just to the east of National Petroleum Reserve-Alaska. The Alpine discovery stimulated interest in the reserve, especially in the oil-prone northern Barrow Arch. However, the possible construction of a gas pipeline also has enhanced the prospects for the southern gas-prone area in the foothills of the Brooks Range. The Gubik gas discovery and several other smaller gas fields demonstrate the potential for gas in this southern area. A Department of the Interior report estimated

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FUTURE OIL AND GAS ACTIVITIES that the National Petroleum Reserve-Alaska has undiscovered, technically recoverable reserves of 2.1 billion bbl of oil and 8.5 TCFG. A USGS report (Bird and Houseknecht 2002) lists the TRR volume of oil as 5.9 billion to 13.2 billion bbl, with a mean expected value of 9.3 billion bbl. The new estimate of gas potential is 40-85 TCFG, with a mean expected volume of 60 TCFG. That evaluation presents results for new data, new play concepts, and better seismic data; it offers a 3- to 6- fold increase in the TRR estimate. Barrow Arch Trend The northern portion of the National Petroleum Reserve- Alaska lies over the Barrow Arch, which trends westward across to Barrow. The Barrow Arch is parallel to subparallel to the coast and serves as a focusing mechanism for hydro- carbons that migrate out of the deep basins and as such fa- vors the accumulation of oil and gas. The search for com- mercial quantities of oil has focused on this portion of the reserve. The Barrow Arch trend that portion of the reserve from the coast of the Beaufort Sea south to about 69 45' N latitude could be an area of active exploration over the next 10-15 years. Despite restrictions on drilling and on place- ment of surface facilities, leasing is likely to be vigorous, as is drilling activity, which will be aided by new technologies and the use of three-dimensional seismic data. The potential exists for several moderate to large oil fields, in the size range of the Alpine field, and for numerous smaller satellite fields. Competition should increase, especially in those ar- eas more remote from current infrastructure and production, where the established producers would have less advantage. None of the larger fields found in the post-2001 period is likely to be producing before 2008, because the time required to delineate the accumulation and build the necessary infra- structure is seasonally limited and earlier, more proximal discoveries would have priority. The larger fields can be expected to have a life of 20 years or more. Gas discoveries would lag somewhat behind the oil fields in terms of investment and development. If built, a trans-Alaska gas pipeline probably would not be in opera- tion before 2009, and the gas reserves at Prudhoe Bay would be the focus of any early development, followed by those at Point Thomson and perhaps by discoveries in the Brooks Range foothills because of their proximity to the pipeline. Gas fields in the northern portion of the reserve are not likely to be developed and put in production before 2020. Exploration in the northern portion of the National Pe- troleum Reserve-Alaska could add 3 billion bbl to the North Slope's reserve base. The bulk of these reserve additions would occur over the next 10-15 years, but if gas is present in commercial quantities, its development will follow that of oil. A reasonable estimate for gas reserves is 5-10 TCFG. The 2002 resource evaluation (Bird and Houseknecht 2002) suggests that, for the northern portion of the reserve, the 55 mean expected TRR for oil is 7.5 billion bbl and the mean expected TRR for gas is 20-25 TCFG. The Alpine model, or refinements of it, would be used for exploration, development, and pipeline construction. A1- though the footprints would be small, even assuming ad- vanced construction techniques and the uncertain ability to forgo a permanent gravel road for maintenance, pipelines to this area would greatly extend the web of aboveground struc- tures. If commercial discoveries extend to the vicinity of Barrow, the pipeline system would extend more than 403 km (250 mi) from east to west, with spur lines 32 to 81 km (20 to 50 mi) long, trending north-south from the trunk lines. The system of pipeline and infrastructure in the newly devel- oped areas would look much like the Alpine field does to- day, but the accumulation of fields would affect a larger area. Brooks Range Foothills The area from the latitude of Umiat and Gubik to the National Petroleum Reserve-Alaska's southern limits is thought to be predominantly a gas-prone province. Studies of the Umiat oil field indicate potential for additional rela- tively substantial oil accumulations, and the Gubik gas field and other smaller discoveries at Square Lake and Wolf Creek provide evidence of the potential for gas. All previous ex- ploration in this area was for oil. In the near term, the foothills region could be the least active area, producing less than even the Beaufort OCS. To achieve a large amount of activity, a series of events must occur in the other exploration subdivisions of northern Alaska. They include building a gas pipeline, establishing a reliable market and price for gas from the major gas fields of the northern portion of the Colville-Canning Province, dis- covering sufficient gas reserves in the Colville-Canning foot- hills to support a new infrastructure and pipeline system, and maintaining enough capacity in the pipeline system to sup- port additional volume. If those conditions are met, explora- tion and development would proceed in the same general fashion as elsewhere on the North Slope. An individual gas field in this region could have reserves of 5.0 TCFG or more, but the size of any oil fields is antici- pated to be limited and not to exceed 200 million bbl, which could be too small for development as a standalone field. Currently available data are limited, but undiscovered gas reserves could be 15-20 TCFG. The 2002 USGS estimate (Bird and Houseknecht 2002) places a mean of 35 40 TCFG in the central and southern portions of the reserve. Oil accumulations are expected to be small by North Slope standards; economically recoverable reserves are esti- mated between 500 million bbl and 1 billion bbl. In contrast, Bird and Houseknecht (2002) suggest that there is an ex- pected mean TRR of 1.9 billion bbl in the southern portion of the reserve. Any exploration and development would probably oc- cur after activity in the other exploration subdivisions and

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56 probably not before 2015. The scale and style of operations would be similar to that at Alpine. Spills are not a concern with gas, but the extensive pipeline system that would be required to transport the gas to a trans-Alaska gas pipeline would be conspicuous if it were not buried. Arctic National Wildlife Refuge 1002 Area Whether Congress will open the area to oil and gas ex- ploration is unknown, but it is useful to assess what might happen if it did. Of the Arctic National Wildlife Refuge's approximately 8 million ha (19 million acres) (Bird and Magoon 1987), the only part with potential for oil and gas exploration and development is the coastal plain 1002 Area of approximately 607,000 ha (1.5 million acres) (Bird and Magoon 1987~. The Kaktovik Inupiat Corporation, which controls the surface mineral rights, and the ASRC, which controls the subsurface mineral rights, own an extensive in-holdina in the north-central portion of the 1002 Area. This portion of the North Slope has long been considered to have great po- tential for oil and gas. It lies between the Prudhoe Bay area fields to the west and the numerous, but as yet uncommer- cial, discoveries in the Mackenzie delta area to the east in Canada. If the first federal lease sale were held in 2006, oil production could begin by 2013 and gas production by 2020. Estimates of the oil and gas potential of the 1002 Area vary. The current USGS evaluation of the Arctic National Wildlife Refuge (Bird and Houseknecht 1998) assigns a mean TRR of 10.3 billion bbl for oil (conservatively, this is an ERR of 3.2 billion bbl) and 8.6 TCFG (no estimates of economically recoverable gas were made). Unpublished in- dustry evaluations suggest that higher ERR volumes of oil and gas are possible. Exploitation of reserves of that size, if realized, would extend the productive life of the older fields. PROJECTIONS OF DIRECT EFFECTS TO THE YEAR 2025: INFRASTRUCTURE ANALYSIS The committee's projections of direct effects are based primarily on trends from the past 13 years (Figure 5-1~. By 2025, the road network would expand by another 129 km (80 mi) if the growth rate is constant. This projection, how- ever, could underestimate growth if long roads are built to Alpine or Barrow or are used to connect major new oil and gas fields in the Brooks Range foothills or elsewhere. Based on the 1988-2001 rate of 17 ha (42 acres) per year, the total gravel-covered footprint would increase to about 4,150 ha (10,250 acres) by 2025, and the total area of direct effects (roads, pads, gravel mines) would increase to about 8,000 ha (18,700 acres). An additional 200 ha (500 acres) of gravel mines would be needed to build the roads and gravel pads. Advancing technology and the location and configuration of new oil and gas fields would affect the extent of roads and gravel-covered tundra. Development is likely to include CUMULATIVE EFFECTS OF ALASKA NORTH SLOPE OIL AND GAS more satellite fields on small gravel pads, similar to those at Endicott and Alpine. They could have airstrips and small road systems disconnected from the main road network. Other gravel roads in the area are being considered by the Alaska Department of Transportation and the North Slope Borough (Petroleum News Alaska 2002a), including a 170- km (106-mi) gravel road south from Nuiqsut that would con- nect to the Dalton Highway near Pump Station 2. More ice roads will reduce the need for gravel roads, although ice roads might not be practical in areas with few lakes, such as the Arctic Foothills; areas with little gravel, such as parts of the National Petroleum Reserve-Alaska; or areas that are distant from existing roads. The effects of these roads would accumulate with those of any other roads that might be built for other purposes. For example, the Trans-Alaska Pipeline and the haul road, completed in 1974, covered approximately 4,050 ha (10,000 acres) on the North Slope (Pamplin 1979~. It also is possible that the projections are an underestimate if major support facilities, new causeways, long roads, or air- strips are needed or if ice roads and pads cannot be used. Fewer roads might require more aircraft traffic; insufficient information is available for quantitative analysis of how any such effects might accumulate. CLIMATE CHANGE AND OTHER INFLUENCES ON FUTURE OIL AND GAS DEVELOPMENT The scenario on which we base our projections assumes that climate change will not seriously affect oil and gas ac- tivities on the North Slope. However, as a result of global emissions of greenhouse gases, Earth's mean surface tem- perature is expected to rise by 1-3.5 C (1.8 to 6.3 F) over the next century, and changes in Arctic Alaska are expected to be even greater (Houghton et al. 1995, 1996~. The two principal climate models used in assessments (the Canadian and Hadly Center models) correctly reproduce the observed late-twentieth-century warming, and they predict continued warming throughout Alaska of 4-10 C (7.2-18 F) and 3- 6.5 C (5.4-11.7 F), respectively, during the twenty-first century (Alaska Regional Assessment Group 1999~. The strongest warming is expected in the north, so a plausible (though quite uncertain [Serreze et al. 20001) twenty-first century warming prediction for the North Slope might be 5- 10 C (9-18 F) or 0.5-1 C (0.9-1.8 F) per decade. This exceeds the estimate for mean global warming by a factor of 3 or so. The Arctic amplification is attributed, at least in part, to "ice-albedo feedback": As the reflective areas of arctic ice and snow retreat, the earth absorbs more heat, accentuating the warming (Chapman and Walsh 1993, NAST 2001~. Other predictions are that most of the North Slope warm- ing will occur in the winter, and that precipitation and evapo- ration will increase. The predictions and models are sup- ported by the experience of Alaska Natives, who have reported changes in the amount of ice cover and reduced effectiveness of ice cellars. Some warming has already oc-

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FUTURE OIL AND GAS ACTIVITIES 20000- 18000- 16000- 14000- 12000- u, I, 1 0000- 8000- 6000 4000 2000 57 J ,- me: I! ~ - i!~ : o 1960 1970 1980 1990 Year 2000 2010 2020 2030 Gravel covered area Other disturbance Mined area - Total direct impact area FIGURE 5-1 Cumulative direct effects of early exploratory trails and peat roads are shown with diamonds; gravel mines with triangles; gravel covered areas including roads, airstrips, and pads with squares; and total area of direct effects with circles. SOURCE: Alaska Geo- botany Center, University of Alaska Fairbanks, 2002. curred. The onset of the off-road tundra season is about 70 days later than it was in the early 1970s (Chapter 7~; spring- time warming has led to earlier snowmelt and emergence of vegetation (Griffith et al. 2002~. Additional warming could reduce the usefulness of ice roads and pads or of some off- road technologies. Projected Changes in the Arctic Marine Environment Ice cover in the Arctic Ocean has been shrinking by about 3% per decade over the past 20 years (Johannessen et al. 1999~. The loss of volume could be even greater than that, because Arctic sea ice has been thinning by as much as 15% per decade (Rothrock et al. 1999), from an average thickness of 3.1 m (10.2 ft) in the 1950s to an average of 1.8 m (5.9 ft) today (Weller 2000~. If the trend were to continue, within 50 years the sea ice could disappear entirely in summer (see map, page 18, Boesch et al. 2000~. Even if changes are less dramatic, the amount and duration of open water near the north coast of Alaska is likely to increase substantially. This is significant because ice edges are highly productive regions where inter- actions between physical and biologic processes result in substantial phytoplankton blooms. Those blooms in turn sup- port populations of zooplankton and arctic cod (Boreogadus saida) and their predators (Niebauer 1991, Wheeler et al. 1996~. The migrations of belugas (Delphinapterus Lucas), narwhals (Monodon monoceros), and harp seals (Phoca groenlandica) to ice-edge regions are associated with bursts in productivity and the subsequent abundance of arctic cod in those areas during the summer plankton blooms. The loss of sea ice also would reduce critical habitat for marine mammals and seabirds that use ice shelves and flows as platforms for feeding, resting, reproducing, and molting. Ringed seals (Phoca hispida) depend on stable, fast ice for raising their young. They and polar bears (Ursus maritimusJ are the only marine mammals that regularly occupy land- fast Arctic ice (Tynan and DeMaster 1997~. The species that use and depend on sea ice would not necessarily decrease in overall abundance, because new habitats are likely to be- come available farther to the north. However, if migrations of bowhead whales (Balaena mysticetus), for example, were to shift farther offshore and if populations of seals near the coast were to be seriously reduced, the consequences for coastal human subsistence cultures could be dramatic. In addition, increases in the amount and duration of open water could make the usually unnavigable Northwest Passage available for ocean transport. Already in 1999, Russian com- panies sent two large drydocks to the Bahamas through the Northwest Passage. Oil companies might have improved opportunities for drilling off the coast. The U.S. Navy is as- sessing the implications of the continuing reduction of sea ice for the scope of its operations in the Arctic Ocean (ONR 2001~. The addition of new sea traffic in the Northwest and

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58 Northeast passages could lead to new environmental effects, caused by spills, noise, or collisions, for example, that could accumulate with effects of oil and gas development. Projected Changes in Terrestrial and Freshwater Environments Changes in tundra will result from the direct and the indirect effects of climate change and its drivers. No direct effects on animals from increased CO2 concentrations are anticipated, but direct effects on plants (photosynthetic and respiration rates) would be expected. In addition, there will be direct and indirect effects of temperature changes on plants, animals, and microorganisms. Predicting the effects of warming on tundra ecosystems is difficult because of the complexity of the ecosystem. In addition, the time scales at which different consequences appear are highly variable: some processes begin within a day, others will not become fully apparent for centuries. Few studies have yet been conducted on flat, coastal, polygon-sorted tundra, but the International Tundra Experi- ment system is using passively warmed, open-top chambers in 26 arctic and alpine tundras to compare the effects of warming on plant growth and flowering (Arft et al. 1999, Henry and Molau 1997~. Investigators at Toolik Lake on the north slope of the Brooks Range have shown experimentally that decomposition and mineralization of nitrogen in tundra is strongly limited by low soil temperatures and high soil moisture (Nadelhoffer et al. 1992~. Thus, with increased turnover of soil organic matter because of increased warm- ing, a high potential exists for redistribution of nitrogen from soils (with low C:N ratio) to vegetation (with high C:N ra- tio), but accompanied by little or no net change in ecosystem stocks of nitrogen (Shaver et al. 1992~. If warming were accompanied by decreased soil mois- ture, large increases in respiration would be expected to cause long-term loss of both carbon and nitrogen from the system. In addition, the increased depth of permafrost thaw of would lead to increased losses of mineralized nitrogen because of drainage. If so, increases in nitrogen uptake and net primary production (NPP) in Phase II would be insuffi- cient to compensate for nitrogen and carbon losses attribut- able to leaching and respiration. Therefore, even though the ecosystem eventually would return to equilibrium NPP equals respiration (that is, there is no accumulation of bio- mass through carbon storage) (Vourlitis and Oechel 1997, 1999; Waelbroeck et al. 1997) over 50-100 years there would be a net loss of carbon to the atmosphere. Increases in CO2 concentrations also would result in changes in alloca- tion of carbon and nitrogen among plant tissues, which would affect the palatability of those tissues to herbivores and po- tentially alter the dynamics of herbivore populations. Warmer temperatures could favor the spread of woody plants over portions of the North Slope and increase insect abun- dance and periods of activity. CUMULATIVE EFFECTS OF ALASKA NORTH SLOPE OIL AND GAS Although the depth of the active layer is likely to in- crease in a warmer climate, the general pattern of stream flows is unlikely to change much. Increased snowfall, which is possible, would result in greater spring runoff, and warmer winters should reduce the depth to which lakes and streams freeze, thereby altering wintering habitat for fish and other freshwater animals. Changing Climate and Permafrost As mean air temperatures rise in a warming climate, the earth's surface generally warms by an amount that var- ies locally with vegetation, moisture, snow, and other con- ditions. This surface warming propagates slowly downward into permafrost, typically taking about a century to reach a depth of 100 m (300 ft). Although little direct information is available on the North Slope climate and its 100-year history, temperature measurements in deep wells across the North Slope show that near-surface permafrost tempera- tures, though variable, typically increased by 2-4 C (3.6- 7.2 F) in the century before the 1980s (Lachenbruch and Marshall 1986) and that additional rapid changes have oc- curred since (e.g., Clow and Urban 2002~. These results are roughly consistent with the large changes seen in broadly averaged twentieth-century arctic air temperatures (Chapman and Walsh 1993, Hansen and Lebedeff 1987, Hansen et al. 1999, Figure 13 in Lachenbruch et al. 1988~. Although the early twentieth century warming might in- clude unrelated natural effects (Stott et al. 2000), rapid changes of the past few decades are consistent with anthropogenically driven climate models that predict con- tinued rapid warming in the twenty-first century (Alaska Regional Assessment Group 1999~. As the ice-rich perma- frost warms, its ability to support engineering structures diminishes, so it is necessary to consider how much addi- tional warming is likely and how that might influence fu- ture effects of oil and gas development. Permafrost Conclitions The mean annual surface air temperature over much of the North Slope is -12.5 C to -9 C (10-16 F) (Haugen 1982, Olsson et al.2002, Zhang et al.1996~. The correspond- ing near-surface permafrost temperature is locally variable and typically 2-5 C (3.6-9 F) higher (e.g., Brewer 1958a). The difference is caused by winter snow cover and complex processes in the active layer. This is generally cold "continu- ous permafrost" (no gaps) defined by its temperature (be- neath the 20-meter layer subject to seasonal change) of less than-5 C (23 F) (Lunardini 1981~. Continuous permafrost is robust in the sense that its temperature could be raised several degrees before destructive thawing would begin. By contrast, spatially discontinuous permafrost (with gaps) with near-surface temperatures near 0 C (32 F) is fragile and more easily disrupted by warming.

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FUTURE OIL AND GAS ACTIVITIES Throughout the coastal plain and most of the foothills, measured temperatures near the surface in permafrost are so low typically -10 C to -6 C (14-21 F) (Lachenbruch et al.1982b, Osterkamp 1988) that they could withstand sev- eral decades of warming at the predicted rate before they start the mechanically troublesome transition from continu- ous to discontinuous permafrost. As the climate warms, the natural permafrost temperatures rise, leaving a smaller mar- gin for engineering disturbance. The effects of persistent cli- mate warming could eventually involve failure of neglected structures, or the requirement to modify design, or in some cases, to completely abandon some design options or prac- tices. For example, thicker gravel would be required to pre- serve permafrost as warming proceeds. Abandoned work pads and roads would become unusable when they are cut up by deep polygonal troughs over thawing ice wedges or by other thermokarst degradation. After some degree of warm- ing, preserving ice-rich permafrost with gravel will become unworkable well before the permafrost approaches the dis- continuous state near 0 C (Heuer et al. 1985, Lachenbruch 1959~. Because most of the predicted warming would occur in winter, the period during which nondestructive surface travel can take place over a frozen active layer that is protected by snow cover or ice roads would be shorter, decreasing the capacity for winter operations. Interaction with Climate It is generally assumed that as the mean temperature of permafrost rises, the active layer that thaws each season will thicken. However, where moisture and organic material in- crease the active layer might actually thin as the climate warms (Lachenbruch 2001~. More generally, the change in the physical state, and the associated biotic changes, of the active layer with changing climate are difficult to predict with current information. The difficulty of predicting the effects of changing cli- mate on permafrost and, ultimately, of predicting how ef- fects of oil and gas development might accumulate, involves much more than uncertainty in predicting climate change. We know that the cold deep permafrost that dominates eco- systems and constrains landuse on the North Slope is a con- sequence of low air temperatures, but we know little about the local distribution of those temperatures or other relevant climate parameters, now or in the past. (The topographically diverse North Slope, with an area of 20 million ha [50 mil- lion acres] has four U.S. Weather Bureau Climate stations with records exceeding a decade. Three stations are next to the Arctic coast.) When the climate changes, effects are transmitted to permafrost through poorly understood pro- cesses, physical and biological, that operate in the active layer, whose new state becomes difficult to predict. By con- trast, once a change in mean temperature penetrates the ac- tive layer (and establishes the temperature at the top of per- 59 mafrost) it propagates downward into permafrost predict- ably according to simple physical rules of heat conduction. The shape of the temperature-depth profile to 200 m (660 ft) contains a faithfully preserved, if somewhat ambiguous, his- tory of permafrost surface temperature changes over the past century or more (Clow 1992, Lachenbruch 1994~. The needed understanding of the connection between climate, active layer, and permafrost requires repeated mea- surements in the same place of surface heat balance, snow depth, and temperatures through the active layer and into permafrost (a few meters). This could be done with remote self-contained instrument stations (now available at modest cost) distributed over the North Slope or other areas of con- cern (e.g., Clow and Urban 2002, Olsson et al. 2002~. Infor- mation on the history of temperature at the top of permafrost (the bottom of the active layer) and its rates of change can be obtained from careful down-hole thermal measurements in wells at any location in the continuous permafrost. Permafrost and the Encroaching Sea The steep permafrost bluffs behind the narrow beaches of the Beaufort and Chukchi seas are receding an average of 2.5 m (8 ft) per year; this is the most rapidly retreating shore- line in the United States (Reimnitz et al. 1985~. The bluffs have been retreating rapidly for thousands of years because of the destructive thermal effects of the surf, which thaws and undermines the bluffs and carries away the debris (MacCarthy 1953~. (The retreat can be expected to acceler- ate with warming climate and diminishing sea ice.) The re- treat poses some engineering problems for pipelines and other facilities that cross the shoreline, and it presents a po- tential risk from toxic-waste pits abandoned by "freezeback" during earlier coastal exploratory drilling. But most impor- tant, the marine encroachment controls the temperature and distribution of permafrost beneath the edge of the sea. As the shoreline migrates inland, a coastal point on the North Slope undergoes a dramatic climate change its mean surface temperature increases from about -11 C (12 F), characteristic of land, to -1 C (30 F), characteristic of the seabed (Lachenbruch 1957a). This transition occurs over a band of a few kilometers where the water is less than 2 m (6.5 ft) deep (Lachenbruch and Marshall 1977, Osterkamp and Harrison 1982~. Over this short distance we pass from robust permafrost with a large subfreezing cold reserve on shore to the more fragile subsea condition where surface tem- peratures are close to melting a condition that is character- istic of warm discontinuous permafrost 500 km (300 mi) to the south. The time after inundation required to warm and thaw subsea permafrost is sensitive to little-known details of its salinity (Harrison and Osterkamp 1978, Nixon 1986~. The 600 m (2,000 ft) deep, cold, ice-rich permafrost at Prudhoe Bay could warm to near-melting temperatures from top to bottom about 2,000 years after inundation (or longer depend-

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60 ing on salinity), but its ice-rich condition could persist down to hundreds of meters (60 km [38 mid from shore at current transgression rates) for another 25,000 years (Lachenbruch 2001, figure 5; Lachenbruch et al. 1982a; Nixon 1986~. The importance of the retreating permafrost shoreline for human activities is that the shoreline provides a sharp separation between cold permafrost on shore and warmer permafrost offshore that is potentially more vulnerable to engineering disturbance if it can be destabilized by thawing (i.e., is "thaw unstable". The remarkably rapid retreat yields a transient condition that permits deep, ice-rich (but warm) permafrost to persist offshore to tens of kilometers. Dimin- ishing sea-ice cover from climate warming might further in- crease seabed temperatures, slowly decreasing the cold re- serve of any shallow permafrost there. This is a zone of active exploration and development, including the Northstar project and now-suspended Liberty project. The seabed provides support for artificial islands, causeways, buried pipelines, drill pads, and other infrastructure. OTHER MINERAL RESOURCES The scenario used by the committee to predict the accu- mulation of effects is confined to exploration for and extrac- tion of oil and gas. However, the North Slope contains sig- nificant deposits of other hydrocarbons, especially coal and coalbed methane. If those deposits were exploited in the near future, the committee's scenarios could change dramatically. Because of economic and other uncertainties, the committee cannot predict the degree to which any of these sources will be exploited or when such exploration might occur. Coal The coal-bearing beds on the North Slope of Alaska, mainly in rock sequences of the Nanushuk Group of Creta- ceous age, are well exposed in the western part of the Na- tional Petroleum Reserve-Alaska in bluffs along the Kokolik, Kukpowruk, Utukok, Kuk, Meade, and Colville rivers and have been penetrated in several of the test wells drilled in the northern foothills (Figure 5-2~. They range in rank from lig- nite A to high-volatile A bituminous and are low in ash and sulfur (Sable and Stricker 1987~. Sable and Stricker (1987) estimated the amount of Cretaceous coal on the North Slope at 1.3 trillion metric tons (t) (1.7 trillion short tons of bitumi- nous coal). East of the Colville River, coal beds of lesser potential and rank are exposed in sequences of the Sagvanirktok for- mation of Tertiary age and extend off shore (Sable and Stricker 1987~. Those coal beds rank from lignite A to sub- bituminous B with a mean of sub-bituminous C with low sulfur and variable ash content (Roberts et al. l991~. Stricker (USGS, personal communication, 2002) estimates the total hypothetical volume of the Tertiary coals on the North Slope and offshore Beaufort Sea at 608 billion t. CUMULATIVE EFFECTS OF ALASKA NORTH SLOPE OIL AND GAS Coals of lower Mississippian age are exposed at Cape Lisburne, in the eastern Brooks Range, and in wells south of Barrow (Sable and Stricker 1987, Wahrhaftig et al. 1994~. They rank from low-volatile bituminous to anthracite and are low in sulfur and ash (Conwell and Triplehorn 1976, Tailleur 1965~. Merritt and Hawley (1986) listed the coal volume at Cape Lisburne as 842 million t. Coal was mined on the North Slope at Cape Beaufort to provide fuel for commercial whaling ships as early as 1879 (Schrader and Peters 1904~. Alaska Natives have mined coal in the Corwin Bluffs and in the lower Kuk and the Meade rivers, off and on for many years, but they cur- rently rely mainly on natural gas and diesel oil for generat- ing heat and electricity. Various mining companies have sampled and made preliminary investigations into the fea- sibility of commercial mining of coal for export. The ASRC has recently considered such an operation in the western North Slope. One problem for commercial mining of coal from the western North Slope involves transportation. There are few roads and there is no year-round seaport. The nearest sea- port with docking facilities is at Kivalina, about 320 km (200 mi) by air from the best Cretaceous coal exposures. The Kivalina seaport was built for the export of lead and zinc ore concentrates: It is open for shipping about 100 days each year. Ore concentrates must be shipped on barges about 6 km (4 mi) out to sea where ore ships can be an- chored and loaded. A recently built 84 km (52 mi) road in the De Long Mountains runs from the Red Dog lead and zinc mine to Kivalina (Skok 1991~. A connecting road to a North Slope coal mine could be built to haul coal to Kivalina, but addi- tional storage facilities would be needed at Kivalina. Con- struction of a new seaport at Oumalik Lagoon or Kotzebue and access roads have been suggested for shipping coal from the North Slope (Fechner 1991~. However, large-scale coal mining under arctic conditions, and hauling overland to Kivalina or to a new seaport with dock facilities, probably is not economically feasible in light of competition from exist- ing lower-cost coal operations in Cook Inlet and elsewhere in the United States. The only commercial mining of coal in Alaska, for export to Korea, is from the Usibelli Coal Mine at Healy on the Alaska Railroad, which hauls the coal to a year-round seaport and to loading facilities at Seward. Intermittent coal mining for local use probably will con- tinue unless some other local fuel source, such as natural gas or coalbed methane, is developed for use in small communi- ties in the North Slope and elsewhere in Alaska. Perhaps some innovative engineering plan, such as transporting coal as a slurry in a pipeline to tidewater, or burning coal in place to generate and transport electrical power to market through power lines or by other means, could eventually become economically feasible. However, unless subsidized, substantial coal mining on the North Slope in the near future is unlikely.

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62 Coalbecl Methane The coalbed methane (CBM) potential of the North Slope is estimated to exceed 800 trillion cubic feet (tcf), and could exceed the resources of the contiguous states, approxi- mately 695 tcf. It is estimated that there are 150 significant coal seams, ranging from 2 to 9 m (5 to 28 ft) thick, in the western Colville Basin (slough et al. 2000~. The growth of CBM production in the contiguous states and a new state program in Alaska has spurred interest in developing these resources. The Alaska Division of Geological and Geophysi- cal Surveys (ADGGS) began a program in 1999 to encour- age noncompetitive exploration and development by indus- try of shallow (within 910 m [3,000 ft] of the surface) reservoirs of natural gas, including CBM (slough et al. 2000~. About 25 Alaska communities are atop or adjacent to potential CBM beds. The state, in cooperation with Alaska Native corporations, has set up a demonstration project at three locations, Fort Yukon, Chignik, and Wainwright (Dolan 2001~. The ADGGS, USGS, and the ASNC are co- operating on a study program that includes drilling to collect subsurface data on the geohydrology and potentially recov- erable amounts of CBM. Gas Hydrate Natural gas is expected to be more important in the near term for power generation and transportation because of the general effort to reduce air emissions and the expected de- cline in liquid oil resources. Methane gas hydrate is a poten- tially enormous natural gas resource that is hundreds of times greater than the estimated conventional U.S. natural-gas re- source base (DOE 1999~. Gas hydrate is a solid, icelike ma- terial that contains molecules of gas bound in a lattice of water molecules. On decomposition, a gas hydrate solid can produce as much as 160 times its volume of gas. Gas hydrate occurs in the deep-water regions of the oceans and in perma- frost regions where temperature and pressure conditions are favorable for its formation and stability. Worldwide esti- mates of methane in gas hydrate are 700,000 tcf, and U.S. domestic resources are estimated between 100,000 and 300,000 tcf (Collett 1995, Kvenvolden 1993~. In the 1980s, extensive research and resource estimation programs were funded by the U.S. Department of Energy (DOE), and recent interest in the feasibility of gas hydrate as a fuel has resulted in the National Methane Hydrate Multi-Year R&D Program (DOE 1999~. Major gas hydrate deposits are associated with permafrost regions of Alaska, including those in the North Slope. Many challenges remain before gas hydrate could be- come a producible methane resource, including characteriz- ing its quantity, quality, and location; delineating the safety and environmental consequences of various production methods; and determining the economics of production (DOE 1999~. The goals of the DOE program include removal CUMULATIVE EFFECTS OF ALASKA NORTH SLOPE OIL AND GAS of technological barriers to resource extraction by 2010 and development of guidelines for commercial production by 2015. The onshore Arctic is an initial target area for feasibil- ity studies because of the existing infrastructure and the large estimated volume of gas hydrate in that area. Even optimis- tic estimates suggest that gas hydrate will not become a sig- nificant source of methane for 10-20 years, and more con- servative estimates place routine gas hydrate production as late as 2030-2060 because of technical difficulties and eco- nomic impediments (Milkov and Sassen 2001~. Based on these considerations, the committee's scenarios do not in- clude gas hydrate as a viable component of natural gas pro- duction on the North Slope. Although the economic and tech- nology barriers could be overcome, the first choice will be existing conventional natural gas deposits already character- ized and, in many cases, already being produced but not exported. Base Metal Deposits The North Slope region contains potentially important base metal deposits. For example, the Red Dog lead and zinc mine is on the western end of a mineralized belt that extends east through the southern part of the National Petroleum Reserve-Alaska and through the Brooks Range, mainly south of the drainage divide, in the Wulik River drainage near the village of Kivalina. The area has been explored and studied by the BLM, USGS, and ADGGS. Excellent prospects for lead and zinc deposits have been found. The indicated and inferred original reserves at the main deposit at Red Dog were calculated at 77.1 million t, averag- ing 17.1% zinc; about 13.2 t, averaging 5% lead; and 2.5 troy oz of silver per short ton (85.7 g of silver per metric ton) of ore. Cadmium and germanium are associated with the sil- ver (Skok 1991~. The estimates of the reserves are expected to increase as drilling around the main deposit continues. The main ore body is exposed at the surface and is about 1,300 m (4,400 ft) long; it varies from a few hundred meters to 430 m (1,400 ft) wide and averages about 30 m (100 ft) thick, with a thicker zone near the center ofl40 m (460 ft). Drill hole 26, near the center, intersected 140 m (460 ft) of ore, grading 29% zinc, 8% lead, and 140 g of silver per met- ric ton. The Red Dog is the second largest zinc deposit in the world, but probably the richest. A second deposit, the Hilltop deposit, is located just south of the Red Dog main deposit and is of similar origin and geologic setting. The Hilltop contains copper sulfides, up to 3% copper in some samples, and 1 gram of gold per metric ton. It is estimated to contain several million tons of ore at grades comparable to those in the main deposit (Kulas 1992~. The Red Dog mine is a small open-pit operation. The ultimate pit depth will be about 150 m (500 ft) below the creek bed (Kral 1992~. About 2.27 million t (2.5 million short

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FUTURE OIL AND GAS ACTIVITIES tons) of overburden and waste were removed during mine development and used for road building and other facilities. About 1.8 million t (2 million short tons) of ore are blasted and removed from the open pit each year (about 6,000 short tons or 5,400 t each day, 365 days per year). The ore is milled on site and concentrates moved to Kivalina port on specially designed 75-ton trucks over a 84 km (52 mi) road. There the 63 concentrates are loaded onto barges and towed to larger ore ships about 7 km (4 mi) offshore. Approximately 15 ships of 25,000 to 75,000 tons (70,000 to 210,000 m3 internal capac- ity) call at the port each year during the 100-day shipping season (Cominco 19901. The mine (and related facilities) cost $450 million to develop and is expected to produce for 50 years.