ALASKAN UPDATE

' ·, ''•·· ' ,~ fl' A Research Review Published by Member Companies of the Lease Planning and Research Committee

Summer 1991 Volume 9, Number 2 ALBERTA TEST FACILITY DEMONSTRATES HEAVY OIL PRODUCTION FEASIBILITY Large deposits of bitumen, produced either by mining or naturally occurring asphalt, the surface, or drilling have been discovered in the horizontal wells into the Canadian province of Alberta. deeper formations (See Figure In fact, most of the one trillion 2, page 2). barrels of petroleum found in Alberta is contained in oil Surface Mining - Bitumen sands and heavy oil deposits. deposits found near the sur­ The largest of these deposits face are mined and the oil­ is in the Athabasca region saturated soils heated to li­ near Ft. McMurray (See quefy the oil and allow it to Figure 1, page 2). drain off. Once the mining At this time two commer­ activity is completed, the open­ cial projects are using surface pit mines are revegetated. mining techniques to produce oil. Ninety percent of the Horizontal Drilling - Deep estimated recoverable oil, During a March 1991 tour of AOSTRA facilities, LPRC member deposits are sometimes heated however, is buried too deeply company representatives examine the drilling rig which in situ (most commonly by for extraction by surface min- was modified to drill horizontal wells for the project. injecting high-presure steam ing. The Alberta Oil Sands into the bitumen) until the Technology and Research Authority Conventional Technology asphalt becomes fluid. The liquefied (AOSTRA) was created by the hydrocarbons are then produced Alberta government in 1974 to pro­ Until AOSTRA began testing using conventional oil well tech­ mote the development of new oil alternate production schemes, the nology. Both the injection and sands technology. Alberta oil sands deposits were Continued on page 2 U.S. Departntent of Energy Suntntarizes Arctic Data Development in the Arctic re­ computers (PC's). Its operational • a summary of the contents, quires that engineers have access to software and users' manual are con­ • the most efficient search a wide range of information from a tained on Compact Disk-Read-Only methodology, variety of sources. The information Memory (CD-ROM) media. • individual(s) to contact to obtain these engineers need includes The AORIS is made up of three the information, and history, culture, wildlife preserva­ components, the directory, the • the telephone number(s) of the tion, ice conditions, permafrost, soil bibliographic information system, contact(s). types, vegetation, etc. Recently, the and the scientific and engineering U. S. Department of Energy (DOE) information system. The com­ Information in the directory is developed a data base to provide ponents are linked to one another presented in a matrix which cross­ single-source bibliographic and so that the users may easily move references the sources of Arctic technical information which focuses from one component to another. information with major areas on the specific needs of offshore including energy development. Directory - The directory con­ • Arctic engineering, The DOE Arctic and Offshore tains a listing of 85 sources of • Geology and geophysics. Research Information System (AORIS) Arctic-related data. For each data • Geotechnical, .. runs on IBM-compatible personal base, the AORIS provides Continued on page 8 well drilling technology. Alberta Figure 1. A very large drilling rig Continued from page 1 ~lberta Test Facility Location was modified to handle a production wells are drill­ 12-foot diameter drill bit ed horizontally through and 10-foot diameter cas­ the hydrocarbon deposits ings. Conventional drill­ to increase the size of the ing muds were circulated production zone of each into the hole as drilling well (See Figure 2). The progressed to maintain cost of such wells is high. stability in the well bore. Further, the ''target The ten-foot casings were depth" (producing forma­ cemented into each shaft tion depth) for such wells to ensure hole stability must be fairly deep if and safe operations drillers are to achieve the throughout the life of the appropriate deviation of Ft. McMurray project. the well stem to complete a horizontal well. Drilling Rig - A custom drilling rig was designed to operate The "Missing" Zone - ALBERTA Between the deposits within the confined space near the surface and of the tunnel. Because those of sufficient depth the wells were drilled up­ to produce by directional ward and then diverted or horizontal drilling in a horizontal direction, techniques lies a "miss­ conventional top-down ing" zone. Researchers at drilling procedures were AOSTRA focused their not always applicable. attention on developing New techniques were technology for production developed for drilling from the "missing" zone. fluid pressure control, about a half mile of tunnels (12 feet well surveys, logging, and running The AOSTRA Facilities high by 15 feet wide) extends from casing under pressure. the shafts. From the tunnels, wells The AOSTRA Underground Test are drilled at a shallow upward Pilot Project Tests Facility (UTF) consists of twin ver­ angle into the oil bearing strata (See tical shafts about 10 feet in diameter Figure 3, page 3). Oil has been produced from the and over 600 feet deep. The shafts To accomplish their work, engineers AOSTRA facility utilizing a steam­ terminate in the limestone underly­ employed highly-specialized equip­ assisted gravity drainage (SAGD) ing the oil sands. A network of ment. process. As shown in Figure 4, a pair of horizontal wells is drilled Vertical Shafts - The mine shafts through the oil bearing formation. ALASKAN UPDATE were drilled using conventional oil- High pressure steam is injected to Published periodically by the member companies of the Lease Planning and Research Committee (LPRC) of the . , Figure 2. Alaska Oil and Gas Association (AOGA). Conventional, Bitumen ·Production Technology Member companies are: Amoco Production Company ARCO Alaska, Inc. BP Exploration, Inc. Conoco, Inc. ALBERTA Chevron U.S.A., Inc. TEST FACILITY • Elf Exploration Exxon Company, U.S.A. Marathon Oil Company Surface Mobil Exploration&: Producing U.S., Inc. Mining Zone Shell Western E&:P, Inc. UNOCAL ''Missing'' Address correspondence to: Sue A. Duthweiler, Editor ~ ~ Zone Alaskan Update clo Alaska Oil and Gas Association 121 West Fireweed Lane #207 Directional/ Anchorage, Alaska 99503 Horizontal Mailing list: Any individual or group may Drilling Zone write the address above to be put on the mail­ ing list free of charge. Back issues are also available at no charge. ®:> Oil Sands

2 Alaskan Update Figure 3. Figure 4. Underground ~ Test Facility Cross-Section of Producing Well ~\\\\\\\~\\\\\\\~ Top of Reservoir-

Steam Injection Oil and Condensate are Drained Continuously \\\ \\\\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \\ Source: A OSTRA Bottom of Reservoir Source: AOSTRA warm the heavy oil. Once the oil is has resulted in development of market circumstances change, this liquefied it flows downward into the technology that is more economical form of in situ recovery may production line. The oil and water than that previously available. As become commercially viable. (condensed from the injected steam) are then pumped to the sur­ face for processing. Completed wells stand Initial project wells extended into ready to produce the producing formation about 180 heavy oil at the Ft. feet from the tunnels. Because of McMurray AOSTRA encouraging well test results, site. AOSTRA plans on testing additional wells which will be completed to 1,800 feet in horizontal length. Under present market conditions, the technology described here is not economic. The research, however, LPRC In 1978, the Alaska Oil and Gas being considered or already • To promote, conduct, or take Association established the Lease adopted by various governmen­ part in studies and investiga­ Planning and Research Committee tal agencies which affect the tions consistent with the Com­ as a special committee to coordinate Alaska exploration, develop­ mittee's overall goals. the Association's activities relating ment, and production industry to both Federal and State lease sales Since the Committee was in Alaska. More familiarly known as • To consult with governmental established its members have par­ the LPRC, the Committee is made agencies on issues affecting the ticipated in more than 380 research up of businesses engaged in explor­ petroleum industry in Alaska. projects on such topics as regional ing for, producing, transporting, or environmental conditions, ice refining petroleum products. The • To prepare and coordinate thicknesses and movements, off­ current membership includes presentations for public shore drilling structures, oil spill Amoco, ARCO Alaska, BP Explora­ hearings. cleanup, marine transportation, tion, Chevron, Conoco, Elf Explora­ gravel and ice island construction, tion, Exxon, Marathon, Mobil, Shell, • To work with committees, aca­ oceanography, and engineering for and UNOCAL. demic organizations, and local frontier areas. Expenditures for communities, to exchange ideas these projects total more than $330 The Committee's goals are: and views on matters of mutual million (See Alaskan Update, interest and to support studies Volume 9, Number 1). Brief reports • To conduct a cooperative effort which may increase the ability on current LPRC projects appear to become familiar with and to of the industry to conduct petro­ regularly in the Alaskan Update. stay informed of the laws, rules, leum operations in the arctic regulations, and other actions and sub-arctic environments.

Alaskan Update 3 How does the oil industry minimize the size of its production facilities? What are the Q&A: benefits of improved technology in this area?

During the time that has elapsed could be drilled much closer horizontally from the drilling rig since production began in the together safely. (See Figure 2, page 5). In arctic Prudhoe Bay Field (nearly fifteen areas where permafrost is present, years ago), oil companies have con­ In-fill drilling - New, smaller the shaft is usually drilled vertically tinued to develop new arctic tech­ drilling rigs were constructed to through the permafrost and then nologies that result in smaller, less work between existing wells, and "kicked out", that is diverted toward intrusive, and less expensive, ex­ operators began a drilling program the target. The "bend" in the well ploration and production facilities. which utilized spaces between older can be accomplished by using This article discusses some of the wells (See Figure 1). In general, this special drilling tools and techniques technology that has been im­ program resulted in three or four which direct the hole along the plemented. Because the charac­ desired path. Specially designed teristics of oil fields vary with sensors allow the drillers to track regard to depth of oil and gas F'ig~n11. the course of the well as it is drilled deposits and environmental condi­ ln... fiU ·Drilling so they may make adjustments as tions at the surface, not all of the necessary. techniques for reducing the size of The horizontal distance a bottom facilities are applicable in every D D hole location may be displaced from development. the surface location of the drilling The size reductions discussed 0 ' '0 rig is controlled by the depth of the here include changes at onshore downhole location and by the gravel well pads where oil field 0 0 region's geological characteristics. In operators have reduced well spac­ D D general, the deeper the downhole ing, completed "in-fill" drilling at location, the further it may be older sites, and utilized directional 0 0 laterally displaced from the surface drilling techniques. Additional sav­ 0 0 location. Where sand, or other ings in well costs and space utilized geologic formations subject to col­ are achieved by sequential use of D D lapse may be enountered, direc­ facilities. tional drilling might be limited or ; Old Wells precluded altogether. Reduced Well Spacing The well angle that may be attain­ = New Wells ed is also determined by technical, Significant facility size reductions geological, and economic factors. In have been achieved at onshore pro­ general, the more horizontal the duction well sites through reducing well, the more expensive it is, and, the spacing between new wells and times as many wells drilled within the more likely drillers are to have drilling new wells between old ones. the same pad as the older wells. difficulty in maintaining it. "Old" wells - Design criteria for New wells - As development Sequential Use of Wells the orginal development wells in the continues at Prudhoe Bay, followed Prudhoe Bay Oil Field called for by new work at the Kuparuk and The requirements placed on wells spacing between the wells to be Milne Point Oil Fields to the west change as an oil field matures. For greater than the size of the thaw and at the Endicott Field to the example, some wells may be rework­ bulb that was expected to develop east, operators have continued to ed to produce from another zone; around the well as hot oil flowed to drill wells as closely together as other wells may be productive dur­ the surface. Wells in this oil field safety and existing drilling equip­ ing the early stages of production, I are drilled through approximately ment allow. Typical well spacing is but become marginal later. These 2,000 vertical feet of permafrost. now between 25 and 35 feet in wells are often modified to extend I (For more information on perma­ most areas onshore, compared to their useful life. frost, see Alaskan Update, Volume 110 to 120 feet between wells drilled 7, No. 2.) Engineers expected thaw­ during the early phases of Arctic Recornpletions - Although a well ing and subsidence to occur around development. In the Endicott Field, may pass through several formations each of the wells. To be conservative typical well spacing is 10 feet. or zones capable of producing oil in establishing design criteria, wells and gas, it is used to produce from were spaced so that the thaw bulb Directional Drilling. only one at a time. Wells are "com­ from one well would not intersect pleted", that is perforations are with that from the next. Once oil Technology has gradually evolved made in the lower portion of the began to flow, engineering staff which allows drillers to direct a well casing, so that oil may flow studied the thaw behavior around well bore to a subsurface target into the pipe from the desired zone. the wells and learned that wells location which is some distance When production diminishes from

4 Alaskan Update one zone, the perforations are Figure 2. plugged with cement and the well is recompleted by perforating into Directional Drilling another zone.

Waterflood - Existing wells may Surface be converted to waterflood during Location the production life of an oilfield. In this case, water is pumped down­ ward into the formation to push oil toward producing wells. t Approximately 2,000 Feet Permafrost Injection - These wells may also be converted to injection wells t through which water produced with the oil or other oilfield fluids may be injected into a subsurface ------X Target Location formation. These wells are operated under special permits from the U.S. Environmental Protection Agency (EPA). impacts to the environment. north coast, improved technology Benefits Smaller footprints result in less may allow development of near­ change in habitat and minimiz­ shore oil fields from onshore loca­ The benefits of these technological ed disruption to wildlife. tions, eliminating the need to con­ changes include reduced disturbance • More efficient utilization of struct causeways to offshore to the land and animal habitat in scarce construction materials, facilities. development areas due to generally such as gravel, while minimiz­ A less obvious benefit of this smaller facilities, and lower oil and ing the need to haul in addi­ changing technology is an enhanced gas production costs. Important tional material and equipment flexibility in facility siting. Improved benefits of these reductions of the from outside the region. directional drilling technology physical size of production facilities • Minimization of construction, allows engineers, government agen­ include maintenance, and production cies, and others, to work together to • Minimization of the "footprint" costs. determine where a facility can best of development and the related In some locations along Alaska's be constructed. New LPRC Projects The following new research pro­ Project #382 - Arctic Production Project #384 - Sliding Resistance jects were presented at recent Platforms Update: of Spmy-Ice Surcharged, Grounded meetings of the Technical Subcom­ The primary objectives of this Rubble on a Soft Seabed: mittee of the Lease Planning and program are to provide cost The objectives of this study are to Research Committee (LPRC). Pro­ estimates for, and direct com­ • Develop a strength model for jects are sponsored by individual parisons of, a number of different submerged rubble, companies, companies that supply structural configurations ap­ • Develop a strength model for the oil industry, government agen­ propriate for use in the Beaufort the rubble-seabed interface, cies, and universities. These spon­ and Chukchi Seas. The project will • Obtain full-scale verification of sors or participants share the cost investigate the suitability of each the strength models through of a project. concept for a range of water depths, field experiments cwried out in These and previous projects are and consider the sensitivity of each the Canadian Beaufort Sea, listed in a reference book titled A Com­ design to variations in ice loads, • Optimize the use of surface pilation and Description of Industry soil conditions and wave heights. snow cover to mitigate first -year Research Projects in Alaska Frontier Structural configurations which will ice thickness with the aim of OCS Areas. The book is maintained be evaluated include vertical-sided reducing design loads on off­ for the LPRC by the Alaska Oil caissons and broad-necked cones, shore structures operating in and Gas Association, 121 West Fire­ each in both steel and concrete con­ the landfast ice regime, and weed Lane, Anchorage, Alaska 99503. struction. Topside facilities re­ • Design, build, and test (in the Copies of the book are filed with quirements will also be considered. Beaufort Sea) a heliportable the Anchorage libraries of the Min­ The investigators will evaluate spray ice system. erals Management Service and the potential fabrication sites, towing Arctic Environmental Information and and installation requirements, and The contractor is Esso Resources Data Center (AEIDC), and in the operational aspects of alternative Canada Limited. Two companies Cold Regions Research and Engineer­ structures. The contractor is Sand­ and the Canada Oil and Gas Lands ing Laboratory (CRREL) library in well Inc. Nine companies are par­ Administration are participating. Hanover, New Hampshire. ticipating in the project. Continued on page 8

Alaskan Update 5 Alaska State Lease Sales In order to provide a more stable public meetings. Once the appropriate lease sales were held by the Divi­ and predictable schedule for the reviews are completed, the Division sion of Oil and Gas. The sales of­ development of Alaska's petroleum of Oil and Gas issues a Notice of fered rights to explore for oil and resources on a competitive basis, Sale and Terms. The final lease sale gas on State lands on Alaska's the State of Alaska, Department of notice will include such information as North Slope (Sale 70A, Kuparuk Natural Resources, Division of Oil minimum bid and royalty require­ Uplands Exempt; and Sale 64, and Gas, updates its proposed five ments, and stipulations which address Kavik), in the Beaufort Sea (Sale 65), year oil and gas leasing program specific concerns unique to the sale and in the Cook Inlet region (Sale every year. As shown in Figure 1, area. These stipulations are intended 67, Cook Inlet Exempt). The general the Division of Oil and Gas solicits to assist in the protection of environ­ location of each of these lease sales information from the public mental or cultural resources. appears in Figure 2 (see page 7). regarding Four of the five sales scheduled • new areas to be added to the during 1991 have already been held. Kuparuk Uplands Exempt, Sale 5-year program, Terms and results of the sales are 70A - Located generally south of • revisions to areas already in­ discussed below. The 5-year program the Kuparuk and Prudhoe Bay Oil cluded in the program, and calls for thirteen additional sales Fields and between the Colville and • social, economic, and en­ through the end of 1995, including one Canning Rivers, the lease sale. of­ vironmental considerations of in September of 1991, and three during fered 532,153 acres in 135 tracts. A each proposed sale. each of the four following years. minimum bid of $5.00 per acre The State also conducts land with a fixed royalty rate of 12.5% status checks, . prepares applicable Recent Sales was required on each tract. Total impact statements, including an receipts from the sale exceeded $27 Alaska Coastal Management Plan During the first six months of million. The highest bid for a single consistency analysis, and holds 1991, four competitive oil and gas tract was in excess of $3 million,

Figure 1. Alaska Department of Natural Resources, Division of Oil and Gas Five-Year Oil & Gas Leasing Program As of January 1991 Proposed Sate 1990 1991 1992 1993 1994 1995 Area & Date s 0 N D J F MA M J J A s 0 N 0 J F MA M J J A s 0 N 0 J F MA M J J A s 0 N 0 J F MA M J J A s 0 N 0 J F MA M J J A S 67 A-Cook Inlet F Exempt 1-91 s 70A-Kuparuk F Uplands 1-91 s

64-Kavik p 6-91 M F s

65-Beaufort p Sea 6-91 M F s 74-Cook Inlet p 9·91 M F s

61-Whlte Hills c p 1-92 3 M F s

68-Beaufort c p Sea 5·92 L 3 M F s

75-kuparuk c p Uplands 9-92 l 3 M F s

76-Cook Inlet c p 1-93 l 3 M F s

77-Nanushuk c p 5-93 L 3 M F s

57-North Stope . C c p Foothills 9-93 2 l 3 M F s

78-Cook Inlet c c p 1·94 2 l 3 M F s

79-Cape c c p Yakataga 5-94 2 l 3 M F s 80-Shaviovik c c p 9-94 2 l 3 M F s 81-Beaufort c c c p sea 1-95 1 A 2 l 3 MF s 82-lcy Cape C c c p M F 5-95 1 A 2 l 3 s 83,.Western Beau- C c c p M F fot1 Sea &-95 1 A 2 l 3 s A 5 Proposed Sale Area Added to 5-Year Program. L 5 Preliminary Land Status Check M 5 Public Meeting or Teleconference C 5 Call For Comments: P 5 Preliminary Finding I Notice of Intent F 5 Final Finding I Notice of Sale and 1 5 New Sales and 5-Year Program Revisions Issue Final Finding [AS 38.05.945(a)(3)] I Terms [AS 38.05.945(a)(4)] 2 5 Request for General Information ACMP Consistency Analysis. (If required.) s 5 Sale 3 5 Request for Socioeconomic and Environmental Information Source: Division of OiJ and Gas

6 Alaskan Update submitted by Conoco Inc. total of 490,090 acres was and Petrofina Delaware, Inc. Figure 2. offered for sale. The bidding For additional information Alaska State Lease Sales method for this sale was a on lease sale results, see cash bonus with a 16.33% Table 1. Kuparuk Lease Beaufort Sea fixed royalty. Of the 108 Sale Area - 70A Lease Sale tracts offered, 36 were sold. Kavik, Sale 64- Located Area- 65 Total receipts from the sale inland between the were nearly $7 million. The Sagavanirktok and Canning highest bid for a single tract Rivers, the Kavik sale area is was $977,000, submitted by immediately west of the Exxon and Chevron. The Arctic National Wildlife western lease sale area Refuge. The lease sale of­ received no bids. fered 754,542 acres in 140 tracts. The bidding method ' Cook Inlet, Sale 67A­ for this sale was a cash These leases are located in bonus with a 12.5% fixed the Cook Inlet region both royalty. Of the 140 tracts of­ on- and off-shore. The lease fered, only 6 were sold. sale offered 549,364 acres in Receipts from the sale 140 tracts. The bidding amounted to $242,000. method for this sale was a A cash bonus with 12.5% fixed Beaufort Sea, Sale 65 - I ,.,., royalty. Total receipts from Located primarily offshore the sale of 56 tracts exceed­ between Simpson Lagoon and Flax­ westerly portion of the lease sale ed $5 million. The highest bid for a man Island, the eastern portion of area lies between Pt. McLeod and single tract was $515,000, submitted the lease sale area is centered on Atigaru Point, offshore from the by ARCO Alaska Inc. and Amoco the barrier islands. A second, Naval Petroleum Reserve-Alaska. A Production Company.

Tablf'J.j'JI~ State of Alaska Division of Oil and Gas Colllpetitiv(l Oil and Gas Lease ~al(' Results Januaty thro11gh June, 1991

Kupamk Uplands Exempt, Sale 70A Beaufort Sea, Sale 65 Number of Number of Apparent High Bidder 'Ifacts Apparent High Bidder Tracts ~ll1erada Hess Corporation 20 ARCO Alaska fAd~ 2 ARCO Alaska; Inc. 38 Bac~n~ral;ld •.·...• ·:?rsgren 4 BP Exploration (Alaska} Inc. 12 BP ~xplor~~pn 8 l3P ~~l~~ati~X1 .. ({\laska).lj16., Nippon North Slope 3. Chevron 4 Oil . ~.():. .Ltd., J'~co Pl'O~ucing Inc. Conoco/Petrofina. a •SP ~~~~?~atiop {Alaska} l~c. 1 Nip~o.~ NOrth Slope 8 E:xXOntChmrrofi 2 Oil .~~• .Ltd~, Texaco P~uci~g tnt:::·~· Union Oil Alfred.Jallie~ Ill $ Murphy Ojl Co. 4 ~~ ~!!i~o~~a. < •.. •.•·•···.·· .. .. .•. . . < •·•.· > ·... ·.. ·. •...• .: ~p c~!<};Jl~:~iti()tJ..(AJaska) {nc., Union Oil or California f!~tfo~,h~iiJ?~J4W~~ :';I~9~ 6 ·Ghev.ron U.S.A.. Inc. 1 Union Oil.of California 2 ,reJ.?noco lnc. 2 Total 'ftacts Receiving· Bids Conoco l.U¢•~ Petrofina Delaware, I.n¢: 8 ,~~11~ Everette, Burglin 1 Coflk Inlet, ·S•ff;'.fif!.A , ~ith Forsgren 2 .A;ino¢o Production iGoiJ1pany~ Cbttclco 'f Petrofina Delaware, Inc. 1 ARCO Alaska Inc. 5 Union Oil of California 2 ARCO Alaska l~c.; Amoco Production Company 9 Total 'ftacts Receiving Bids 109 ARCO Alaska ll1c.~· Phillips Petroleum. Company 8 Conoco lnc. 4 Danco/A.laska Partnership Ltd. 5 Robert C.. Ely 1 Kavik, Sale 64 Marath()nOil GoiJ1pany ·· ·· .. ·.· ···.·· ·...... 1 ARGO Alaska Inc. 1 Lane Nichols, A. J.ohn Marquardt, l• Scott Wagner 1 Union Oil of California 5 Union Oil of California 2 Union Oil of California, Marathon Oil Company __2!! Total 'ftacts Receiving Bids 6 Total 'ftacts Receiving Bids 56

Alaskan Update 7 !

allows users to compare individual Energy Software Center (NESC), Arctic Data research results with data contained Argonne National Laboratory, 9700 Continued from page 1 in AORIS. South Cass Avenue, Argonne, • Glaciology and hydrology, The sea ice data section concen­ Illinois 60439, telephone (708) • Marine life sciences, trates on the morphology, mechani­ 972-7250. For more information • Meteorology, cal, and physical properties of ice about AORIS contact Harold D. • Permafrost, and ice-structure interaction in the Shoemaker, Ph.D., at (304) 291-4715. • Physical and chemical Beaufort, Chukchi, and Bering Seas oceanography, The data are further categorized by • Terrestrial/fresh water biology, ice type (multiyear ice, ridged ice, New Projects and first-year sea ice, ice island ice, Continued from page 5 • Upper atmosphere physics. natural spray ice, artificial ice, lab grown saline ice, and reinforced ice). Project #385 - Nipterk P-32 Spmy Bibliogmphic Information System Ice Island Ablation Protection - This portion of the AORIS data Development Experiment: base contains over 8,000 references The overall goal of this study was and informational abstracts on DOE initiated the AORIS project to develop sufficient knowledge of energy-related research and in 1985. To begin, the agency con­ spray ice surface ablation and edge engineering activities in the Arctic. ducted a users' needs survey among erosion rates and protective It provides information on such approximately 70 organizations in­ methods to allow the marine topics as offshore structures, volved in Arctic energy development demobilization option to be seismic activity, sea ice, ice gouging including Federal, State, and local included in plans for future spray or scouring, seafloor soils, and agencies; university researchers; and ice islands. Specific objectives subsea permafrost. All bibliographic oil industry-related firms. were to: references included in the system To guide development of the data • Monitor surface ablation and focus on energy development in the base, a panel made up of recogniz­ edge erosion rates until early Arctic. To enhance the data base, ed experts on Arctic energy was summer, nonclassified military, international, assembled. The panel represented private industry, and unpublished the groups that participated in the • Assess the effectiveness of literature have been added. users' survey. various methods of mitigating Users may search the biblio­ Once the AORIS was completed, ablation and erosion, graphic component by keyword(s), a second users' survey was con­ • Assess surface trafficability and author's name, title, data range, or ducted to evaluate how well the edge stability in relation to AORIS identification number. A system met the needs identified docking and off loading, keyword thesaurus has been con­ earlier. User responses were • Investigate methods of improv­ structed to facilitate access to sub­ generally favorable; the primary ing surface trafficability and ject areas. Users may also scan recommendations were edge stability, and author and title lists to find relevant • that the system be updated data. periodically to add any missing • Assess how methods of pro­ information such as absent cita­ viding edge protection could Scientific and Engineering Infor­ tion abstracts, and be developed to extend the mation System - Over 800 tabular • that improved on-line helps be operational life of spray ice and graphic data sets from the added for the infrequent user. islands into the open water bibliographic citations on sea ice season. characteristics are contained in this Availability The contractor is Esso Resources component of AORIS. This informa­ Canada Limited. Three companies tion provides a quick overview of The AORIS is available through and the Canada Oil and Gas Lands scientific data that are available and the Department of Energy, National Administration participated.

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8 Alaskan Update DESIGN EVALUATIONS IN SUPPORT OF OIL PRODUCTION PROJECTS IN PRUDHOE BAY REGION, ALASKA

Victor Manikian * ABSTRACT

Development of oil resources in Northern Alaska has involved the design of nearshore and offshore facilities in the Beaufort Sea. These developments also necessitated the bridging of many Arctic streams. Studies have been conducted to es tab 1 ish design criteria for the safe and economical con­ struction of projects to withstand their production life. This presentation addresses our experience and solutions to a number of ~v-'-+tc related engi­ neering projects from this area. Introduction -· In 1902, while many were prospecting for gold in Nome, Alaska's first oil field, the Katalla, was discovered. In 1957, Richfiel~ Oil, now known as ARCO Alaska, found deposits of crude oil on the Kenai Peninsula at a place called Swanson River Field. More successes for Alaska and its oil partners soon followed. A series of lease sales gave the oil industry the opportuni­ ty it needed to do some exploration in the Upper Cook Inlet, where in 1962, an offshore discovery was made. Today, there are 14 platforms operating in the Cook Inlet, producing both oil and gas. ARCO gradually·discovered its greatest interest was in the North Slope- one of the harshest, most remote and unforgiving places in the world to look for oil. In 1968 after years of exploration, ARCO and Exxon announced that they had discovered a big oil field in Prudhoe Bay. Prudhoe Bay is a unitized field with Standard, ARCO, and Exxon being the major interest owners. Standard is the Opera tor of the Western ha 1f of the fie 1d and ARCO the Eastern half. Since it began operating some ten years ago, the Prudhoe Bay field has produced an average of 1.5 million barrels a day. West Dock and the Seawater Treating Plant To produce oil in the remote area of Prudhoe Bay, the oil companies have had to build a variety of specially designed industrial complexes. These modular units are built in the lower 48 states and then barged up to the North Slope.

* Staff Civil Engineer, ARCO Alaska, Inc., Anchorage, Alaska

1 Manikian Initially East Dock was constructed to handle barge traffic in four feet of water in Prudhoe Bay. However, due to dredging requirements in the shallow bay, the West Dock (Dockhead No. 2) was constructed into the Beaufort Sea which required a 3, 700 feet 1ong grave 1 causeway from the shore 1i ne, to a water depth of 5.5 feet. The first major barge shipment headed north for Prudhoe back in 1975, two years before oil actually started flowing in the Trans-Alaska pipeline. This pa rti cu 1a r sea 1i ft ran head-on into some of the most treacherous ice conditions seen in the Beaufort Sea since the late 1800's. Mountains of ice and a series of Arctic storms in August forced several of the barges to turn back to the South to become one of the largest overland transports ever seen. By late September, the ice finally allowed the remaining barges to move within a mile of Dockhead No. 2. But that was not close enough, so the existing gravel West Dock had to be extended 4,600 feet to the water depth of 9 feet so that the barges• cargo could be offloaded. In 1981 and in 1982, the West Dock had to be extended another mi 1e to pro vi de a horse-shoe shape grave 1 berm in 12 feet of water for the pro­ tection of the Seawater Treating Plant, which was floated and anchored down in place in 1983. The 610 feet by 150 feet barge mounted plant receives and treats water from the Beaufort Sea for pressurization of the Prudhoe Bay oil field through waterflooding. This process enables the recovery of an additional one billion barrels of oil. The plant reduces oxygen from the seawater and eliminates the fines that plug the pores within the reservoir formation (1). The design of the seawater intake was very challenging. Extensive modeling work on the hydrau 1i c performance and potentia 1 ice c 1oggi ng of the intake was conducted. The intake is designed with low entrance velocities so that the fish would not be drawn into the plant. In addition, a marine life recovery system is designed without any moving mechanical parts coming in contact with the fish, whi1e diverting them to the ocean with the help of specially designed jet pumps.

Three buried pipelines in the causeway connect the plant to the shoreline, a 40-inch and 36-inch treated water supply lines and a 10-inch fuel gas supply line. The pipelines installed in thaw-stable gravel above the waterline, designed according to Arctic design criteria can easily be monitored and maintained. The pipelines have been operating satisfactorily since startup. Annual Sealift and Dockhead No. 3 Design Instead of conventional s:eel construction on foundations, the facilities in Prudhoe Bay are constructed in tDe West Coast as prefabricated oil produc­ tion modules shipped on barges every year to the North Slope during the summer open water sealift period, a short four to six week stretch. Most of the barges have a dimension of 400 feet by 100 feet by 20 feet side shell and a 6 feet natura 1 draft. They carry many modules, some having a weight of 3,000 tons with a dimension of 144 feet in length and 67 feet in width. They are offloaded at the West Dock with transport crawlers and moved to where they can serve as processing plants and living quarters.

2 Manikian During the summer of 1982 a permanent wall bulkhead structure was construct­ ed at Dockhead No. 3. The existing Dock No. 3 of 1975 was a gravel struc­ ture. The old dock used the sinking of a barge and installation of a gravel p1 ug for an off-1 oad i ng condition from 1976 through 1981. Due to safety problems and urgency of quick operation, the design of a permanent dock was justified. The 452 feet long dock can accommodate the offloading of four barges at the same time. The bulkhead piles are 30 inch by 18 inch by 170 pounds per feet and are 72 feet long at the dock front wall. The 413 piles have interlocking grooves and cast steel shoes. To assure vertical positioning the key pile, located at the center of the dock face was driven in a drilled hole, and the rest of the piles stabbed through their grooves. Driving was very hard due to large cobbles in the bottom 20 feet of the SO feet penetration piles. A larger pile driver was brought in with a vibratory hydraulic hammer. Since prob­ lems still continued, to reach design penetration, jetting was used with a 2 inch probe at top and an 8 inch air lift at the bottom to lift the cobbles from inside the "H 11 celis of the piling. The dockhead was completed in August 1982 just prior to the annual sealift. The dock has a design with removab 1e fascia fender wa 11 for 1ower barge e 1eva t ions 1ike those with 18 feet of side shells. Putuligayuk (Put) River Bridge Ice Breaker Design The Drill Site 15 access road crosses the Put River with a culverted bridge -·· composed of seven 20 feet wide by 13 feet height culverts. During breakup week of June 1, 1981, flo~ diverters made of corrugated steel filled with gravel located between the culverts and just upstream of the structures failed due to breakup ice loads flowing in the stream. Based on hydrological studies of the Put River, six ice breaker structures were designed to be placed between the culverts, upstream of the crossing for a lateral design ice loading of four feet thick ice with a crushing strength of 200 pounds per square inch. Calculations indicated that 18 inch pipe inclined structures (30° off the horizontal) supported each by three vertical 18 inch pipe piles with 30 feet penetration will provide adequate protection for the culverts against the design ice loadings.

The structural design was analyzed with the "strudl 11 computer program. Findings indicated that moment forces in the connections using only butt welded pipe was exceeding allowable strength values and plate enclosures were designed at each connection to improve moment distribution to the vertical supports. The ice· breakers were placed 15 feet upstream of the culvert headwall to reduce scour in front of the cu 1verts and provide access for rna i ntenance. Photos taken since 1982 indicate that approaching ice sheets fail in bending along the wedge angle design of the inclined structures. The river crossing bridge structure has been functioning properly since 1982. Both the wedge design and inclined ice breaker structures have been used in the past in Alaska.

3 Manikian Slope Protection Evaluations for Arctic Gravel Islands Developments in Prudhoe Bay are located between the Stump island on the west and the Sag River on the east. A number of studies were conducted for a proposed gravel island design for a new field in Prudhoe known as Lisburne Development to establish its design criteria. An oceanographic design hi ndcas t study was conducted, and s·; xteen storms were incorporated into an extreme event analysis for Prudhoe Bay. Storm surge and wave conditions have been hindcast for 21 sites, both outside or seaward of the shoals and inside or landward of the shoals. The shoals at the entrance to the Prudhoe Bay acted as a submerged breakwater, thus reducing the wave height of westerly storms (2). To assist in the final design of the island, a physical model study of nine different Arctic slope protection systems was performed at the Oregon State University in February 1984. The test program was designed to evaluate:

0 Structural stability of the systems under different wave heights and period by measurement of mat uplift magnitudes.

0 Verifying the proposed island and causeway freeboard elevation by determination of the wave run-up variations for different wave heights and periods. --· 0 Measurements of wave overtopping volumes for the establishment of island drainage design criteria. Two sizes of 12 inch thick mat blocks were tested, 4 feet by 4 feet and 2 feet by 2 feet with concrete rubble filter underlayer or heavy woven po 1yes ter fabric design of 56 ounces per square yard. It was determined that permeability of the underlayer filer, whether it is rubble or fabric, effect the performance of the mat system against uplift stability, more so than the un i t wei gh t of the b1 o c k sy stern . The i ni t i a 1 s 1ope test used a tightly woven fabric which gave us some permeability problems and mat uplift. However, slope tests conducted with one millimeter sieve were quite successful.

Subsequent to these tests, the fi na 1 design of the is 1and was determined, which includes articulated concrete mat armoring on 3:1 slopes along the northerly face of the island, and on the sheltered south side of the island a gently sloping 7:1 unarmored gravel profile. Special precautions will be taken at the critical part of the design, which is the transition zone between the two systems. A number of other studies were also conducted for the project final design, most of which can be found in a technical paper presented in the February 1986 ASCE Cold Regions Engineering (onference (3). Sagavanirktok (Sag) River Training Structure Project The Sag River drains about 5,000 square miles of Alaska's North Slope starting at the Brooks Range and discharging into the Beaufort Sea just east of Prudhoe Bay. Since it does not have well defined banks, Sag River at the

4 Manikian Prudhoe bridge location is braided in nature which provides shifting gravel bars in mid-stream. Our principal area of interest in our studies of 1979 was the bridge and causeway crossing of the Sag River just east of the ARCO airstrip. The causeway has been nearly overtopped on several occasions s i nee the construction of the bridge in 1976, the frequency of high water levels was greater than anticipated in the original design, and the develop­ ment of a gravel bar at the west bridge abutment created serio.us scour conditions in the east half of the bridge waterway and its in-stream piling. A flow improvement training structure system was designed to divert the flow away from the western causeway into a direction perpendicular to the bridge. An armored guidebank, an armored T-head spur and a gravel diversion dike was constructed in October through December 1980. Since there are no rocks or riprap in northern Alaska, special linked concrete mats were designed to act as riprap or natural rock reinforcement. Due to permit problems, the construction period was in winter with poor quality work on the gravel and the concrete mat placement. Recent river cross sections taken at the Sag River vehicular bridge indicate . that the training structures appear to be accomplishing their objective of redirecting flow towards the bridge opening. Method for Weakening the Seasonal Ice Cover and Reduction of Ice Forces on Structures in Northern Rivers During the 1981 and 1982 spring breakups, the Sag River at Prudhoe Bay experienced higher than anticipated breakup flood stages and 1arger than anticipated ice floe~. These conditions threatened to exceed the criteria for the design of the vehicular bridge crossing the Sag River. Since that peri ad a new process used by ARCO weakened the sea sana 1 ice cover in the vicinity of the two Sag River bridges. By weakening the ice, we reduce both the acting forces on the bridge in-stream piles and reduce the breakup water stages upstream of the bridge locations (4). Several methods have been used historically to melt or weaken ice. These include the following:

0 Dusting. Dusting is to modify the surface albedo which is reflection of surface cosmic rays on the ice and thereby increase the absorption of short wave solar radiation. This is accomplished on some Alaskan streams.

0 Snow clearing.

0 Exp 1as i ves to phys i ca 11 y brea-k the ice surface.

0 Chemicals to hasten ice melt.

0 Breaking ice into smaller sections by impact. In 1981, ARCO elected to clear snow forming channels through each span of the bridges. The method was not sufficiently successful. Also, in 1981, impact cranes, placed on the bridge, were used to break the ice into smaller sections. This was a hard method to reduce ice sections.

5 Manikian As part of the pre-breakup activities in 1982, a demonstration was carried out on the effectiveness of dusting. The closest available material to dry dust, consisting of finely ground black walnut shells called 11 nutseal 11 was applied to a small area. The demonstration plot melted about one foot of ice, in a period of 13 days. The melt would probably have been more, except, pondage of water on the surface, effectively stopped the penetration of radiation into the ice. During the spring of 1982, ARCO applied a two-part experimental method to weaken ice on the Sag River in the vicinity of the bridges. The first part consisted of c 1eari ng snow from the stream channe 1. The second part con­ sisted of cutting vertical slots in the ice with a ditch witch machine to a depth of six feet for a distance 500 feet up- and downstream of the bridges. The intent was to reduce the ice forces on the bridge piers by reducing the crushing strength of the ice through warming and to reduce the mass of some of the ice floes, by cutting and melting. This ice cutting procedure has been employed every year on the Sag River west channel with success from 1982 through 1987. As a conclusion, the method of clearing snow and cutting slots in ice prior to breakup appears to warm and melt the ice. and to reduce both the mass and ·crushing strengths of ice floes. Ice has been observed to split preferen­ tially along the cuts. The result appears to be less force applied to the bridge piers and at a lower stage than has occurred during previous break­ ups. Culvert Design Considerations in the Arctic for Minimization of Wetlands Impact On the North Slope, drainage patterns are poorly defined and controlled more by growth and melt of ground ice than by erosion and transport of sediment. Thus, consideration of thermal as well as hydraulic aspects of drainage design is necessary.

The predominant minor dra i.nage structures are cu 1verts. Therma 1 design to insure integrity of culverts consists of two basic parts. The first part consists of assuring that heat transferred to the culvert foundation will not cause a thaw settlement failure of the foundation. This may be accom­ modated by assuring the natural subgrade is thaw stable, by excavation of thaw unstable subgrade material and replacement with thaw stable material, or by insulation of thaw unstable subgrade. The second necessary part of culvert thermal design is assurance that embankment soil is competent to provide the sidefill resistance necessary to support the loads imposed on the culvert. Improperly designed culverts may impact the natural environment in many ways. The most common way, and one not unique to the Arctic, is restriction of fish passage. This may result from excessively high water velocities or from culvert outlets perched above the stream bed. A second common environ­ menta 1 impact is pond i ng res u1 t i ng from cu 1verts improper 1y 1oca ted or placed too high in an embankment. Pondage has adverse affects on vegetation and, depending on depth, may either increase or decrease the seasonal thaw. These problems may be minimized by careful planning and location of drainage works.

6 Manikian In summary, ARCO provides drainage through pads and embankments with minimal impact on the environment. This is accomplished economically by the follow­ ing design procedure: 1. Draining Mapping. As early in the planning process as possible, the drainageways and drainage divides are drawn on the most detailed available topographic maps. 2. Summer Field Investigation. Early during the first summer, after the centerline alignment has been selected and staked in the field, the alignment is walked by an experienced drainage engineer to mark the exact culvert location, invert elevation, and skew on the ground. 3. Detailed Design. Final hydraulic design is accomplished by using data from the drainage map and procedures outlined in our drainage design manua 1. Effects of External Loading on Large-diameter Buried Pipelines and Culverts - Summer Versus Winter Construction Large diameter pipelines and culverts, which are considered as unpressurized pipelines, are weak structurally and their ability to withstand backfill and traffic loadings depend on the shape of bedding and sidefill resistance. Winter placed sidefill materials are often frozen and this commonly results in low density material which resists compaction (which may later thaw and canso 1 ida te) . Therefore, the properties of the confined so i 1 that contra 1 the pipe ovalling deflections and stresses are of utmost importance to.their structural integrity. Although extensive use of elevated pipelines are utilized in Prudhoe Bay, buried warm pipelines exist. On the seawater treating plant installation, as was indicated earlier, the pipelines were buried in thaw stable gravel causeway. They were buried for the protection from environmental forces. In the equations which determine deflection and stresses of buried flexible pipe, sidefill resistance is characterized by the constrained soil modulus M . Achievement of an adequate va 1ue of M often requires that the con­ s~ruction specifications ca11 for good granolar material to be placed and compacted on both sides of the pipe. The preferred s i defi.ll rna teri a 1 is a well-graded sand and gravel having the following gradation: Percent Passing Sieve SL:e by Weight 1-1/2" 90-100 3/4 11 75 ... #100 #4 30-85 #40 0-40 #200 0-10 Pit run material meeting this gradation is commonly available on the North Slope of Alaska. The material should be free of snow and ice, and pref­ erably thawed. The following table conveys the major difference in the soil modulus value Ms of the confined soil that controls the overburden stress (5).

7 Manikian Compaction Ms (psi ) Remarks

Minimum 90% Std. 2000 Soils in ditch wall must be Proctor (AASHO granular or initially-thawed, Test T99) stiff fine-grained soil, or ditch width at pipe center­ line must be at least 2.5D. Nominal 1000 Summer placement 600 Winter placement

As a conclusion, summer placement of buried pipelines or culverts with proper procedures is the preferred method in permafrost areas. Subsea Arctic Pipeline Design Factors - Strudel Scour, Ice Pounding, Ice Gouging, and Thermally Related Settlement Design of buried pipeline crossings of rivers and natural estuaries have been investigated for use in Prudhoe Bay; however, none has been construct­ ed. Transport of oil products from potential Arctic offshore production system is a major problem. In many cases, it appears that in deep waters subsea pipeline systems are the most viable transportation concept. Howev­ er, no such sys tern has been constructed, so many Arctic conditions and ...... " .... design factors need to be studies.

Strudel Scour: The first of the design factors~ or hazards in the Arctic/Beaufort Sea is strudel scour, and how they affect the design of buried pipelines, if they are to be placed under the seafloor. Strudel scouring is a complex phenomenon, that occurs yearly during ice breakup like the Sag River, strudel scouring results when river water overflows the fast sea ice and drains through strudel (drain holes in the ice) scouring the underlying seafloor soils. The depth and width of strudel scours is controlled by the following: 1. Water depth below ice. In deeper water, the energy of the vertical water jet is diffused. During one year's survey, it was determined that scour depths were less than 5 feet in water depths greater than 13 feet. 2. Diameter of the strudel hole. A larger diameter hole permits a larger volume of flow. 3. Depth of overflow above sea Tevel. A greater depth of overflow will effectively increase the velocity of the vertical jet. 4. Thickness of ice. The thickness of ice will affect the lateral drain­ age beneath ice. 5. Duration and variation of flow. 6. Physical properties of the seafloor soils.

8 Manikian The mechanism of strudel scour is not well understood. However, it takes about two days to form and is dependent more on local flow intensity (like during short river breakup period) rather than the tot a 1 discharge of the whole stream. Several years of relationship observations until the design of a pipeline system should be conducted to help their design parameters. With this type of information, pipelines can be designed for placement below their formation depths or designed· such that the pipeline stres-ses will allow their deflection into the base of these scour holes. Ice Pounding by Ice Floes. Following breakup and during the open water seasons, ice floes and small ice islands may be pounded into the seabed by waves. The possible detrimental effects of ice pounding on a subsea pipe- 1 ine are: 1) direct impact of a keel; 2) generation of soil bearing pres­ sure; or 3) foundation failure due to exceedance of seabed bearing capacity. Ice Gouging. Seabed gouging by ice keels is an established threat to offshore pipelines in the continental shelf regions of the Arctic. The frequency and depth of gouging have been shown to be dependent on water depth, and generally increase with water depth up to 115' of water. Thaw Settlement: Settlement will occur if permafrost is thermally disturbed by a warm pipe 1i ne. Under natura 1 conditions, the depth of penna frost is relatively stable. A hot oil pipeline introduces a thermal disturbance which may lead to permafrost thaw. Thawing layers of permafrost undergo an initial volume decrease due to the ice-to-water phase change, and may consolidate further, if the resulting water drains away. When the settlement is uniform, it creates only minimal pipe distress. Pipe deformation occurs when differential settlement occurs, due to variables of soil or ice contents. Storage Tank Foundation Design Early in the development of Prudhoe Bay,- a crude oil topping unit was cons t ru c ted to pro c e s s and· pro v i de a v i at i on f ue 1 , gas o1 i ne and d i e s e 1 to North Slope clients. Recently ARCO Alaska, Inc. redesigned the storage tank farm with the addition of a new 27,000 barrel welded tank and the relocation of two existing 5000 barrel tanks. A subsurface soil exploration program and a foundation design investigation of different Arctic designs was conducted supported by FROST2B, a two-dimensional computer thermal analysis. Foundations for storage tanks are critical due to the heavy imposed loads. In areas where soils remain unfrozen, different foundation types are used based on the soil bearing allowables, the most common being the reinforced concrete ringwall design. - Two significant design considerations for foundations in Prudhoe Bay are the continuous permafrost and the annual freeze-thaw cycle of the active layer. Convention a 1 s ha 11 ow spread f cot i ngs do not perform we 11 because of frost heave from the active layer and the large potential for creep failure in the shallower ice-rich permafrost. At grade heated structures are acceptable only if founded on a non-frost susceptible fill pad and the permafrost integrity is maintained.

9 Manikian Initially a foundation design with the 100°F crude oil resting on W24 by 68 beams spaced on 4 foot centers, providing a 2 foot air space between the bottom of the tank and the top of the gravel pad, and 6 inch of insulation just below the beams provided a satisfactory design. This is due to the fact that in Prudhoe Bay we only have 120 days of ambient air above 32°F. The final tank foundation design was revised due to the high cost of struc­ tural beams and the availability of a fin-fan oil cooler in the plant. The temperature criteria for the storage oil was thus set at 35°F for the 240 days beyond the summer period, and addition a 1 therma 1 computer runs were conducted for the tank foundation. The results indicated that the maximum thaw penetration depth below the center line of the tanks was 4.5 feet after ten or twenty years of operation, several feet above the organic soils, with an associate thaw-settlement of less than 2 inch, an acceptable condition (6). Control of Snow Drifting Snow drifting is a phenomenon that cannot be avoided in northern Alaska, but troublesome drifts near production facilities are minimized by proper design of the buildings. In addition, special snow fences that collect snow in predetermined places assist in reducing snow clearing maintenance efforts at oil production drill sites in Prudhoe Bay. Snow drifts behind obstructions such as road embankments have a length of six to nine times the height of the obstruction. Thus buildings are usually located downstream of such obstacles a distance of at least ten times their height (7). Placing the long side of the buildings in the direction of the prevailing wind generally minimizes the drifting problems. The most effective measure to prevent drifting around buildings in Prudhoe Bay has been the elevated design of buildings on piling stilts which provide open wind area of 3 to 5 feet. The function of a collector fence is to cause wind-blown snow to settle before it reaches a facility that requires protection. The fence is ar­ ranged perpendicular to the direction of the prevailing wind so that snow is deposited in front and behind it. Open fencing with 50 percent open areas are placed at a distance about fifteen times the fence height from facil­ ities for protection. While we understand to a limited extent properties of deposited snow and the problems blowing snow creates to buildings and transportation routes if they are to be kept open, snow can be used as an important construction material in the Arctic such as winter transport roads and runways. Wildlife Habitat Enhancement The last topic of this paper addresses a project in Prudhoe Bay initiated by the late Arctic naturalist Angus Gavin. Waterfowl nesting islands composed of gravel mounds with 4 feet diameter at the top surface and proper side slopes, were installed in lakes in Prudhoe Bay as wildlife habitat enhance­ ment. These waterfowl nesting sites provide protection from foxes and are

10 Manikian located adjacent to adequate food sources near lakes that contain emerging grasses.

REFERENCES

1. "Offshore Seawater Treating Plant, Waterflood Project, Prudhoe Bay Oil Field, .. ARCO Alaska, Inc. Publication, December 1984.

2. 11 Proceedings of the 45th Meeting of the Coastal Engineering Research Board, 14-16 May 1986, Fairbanks and Homer, Alaska," published by Coastal Engineering Research Center, U.S. Army Engineer Waterways Experiment Station, December 1986.

3. 11 Design Evaluations in Support of Offshore Facilities and Gravel Islands in the Arctic, .. Proceedings, Fourth International Cold Regions Specialty Conference, ASCE, Anchorage, Alaska, pp 235-251, March 1986 (V. Manikian, J. Machemehl, and P. Gadd).

4. "Method for Weakening the Ice Cover in Northern Rivers, 11 Proceedings, Arctic '86 Conference: Civil En ineerin in the Arctic Offshore, ASCE, San Francisco, Ca ifornia, pp 239-250, March 1985 V. Manikian and G. N. McDonald). 5. "Effects of Ex terria 1 Loadings on Large-Diameter Buried Pipelines," Proceedin s, Arctic '85 Conference: Civil En ineerin in the Arctic Offshore, ASCE, San Francisco, Ca ifornia, pp 754-762, March 1985 H. P. Thomas and V. Manikian).

6. "Storage Tank Foundation Design, Prudhoe Bay, Alaska, 11 Proceedin s, Permafrost: Fifth International Conference, August 1988 V. Manikian, D. E. Bruggers, M. Tabatabie).

7. 11 Predicting Profiles of Snowdrifts in Topographic Catchments, 11 Western Snow Conference, ApriT 1975 (R.D. Tabler).

11 Manikian