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Muskeg access, with special reference to problems of the petroleum
industry
NATIONAL RESEARCH COUNCIL
CANADA
ASSOCIATE COMMITTEE ON SOIL AND SNOW MECHANICS
TECHNICAL MEMORANDUM
NO.
43
MUSKEG ACCESS, WITH SPECIAL REFERENCE TO PROBLEMS
OF THE PETROLEUM INDUSTRY
BY
NORMAN W. Radforth
f
- )C.
ｾｌｃｬａＮＮＮＮＮ
'fV'..;;."'l
')vCt \', r '\AA..LL,..
J.D_...
ｾｃ
(
Petroleum and Natural Gas Division, Calgary, May,
1956
Reprint of Transactions,. Vol. LIX,
1956,
p ,
271-277
OTTAWA
Problems
to
Reference
Industry
With Special
Petroleum
Access,
of the
Muskeg
*
By NORMAN W. RADFORTH
(Petroleum and Natural Gas Division, Calgary, 'l'Ia.,!, 1956)
(Transactions, Volume LIX, 1956, pp. 271-277)
INTRODUCTION
I
T SHOULD NOT be surpris-ing that m.usleeq is not a clearly understood expression. The term is in extensive use, but its appearance in scientific literature is comparatively rare. Lewis and Dowding (2) have used it in identifying a particular kind of en-vironment for which they wanted to classify vegetation for botanical characterization. Largely, they con-tributed to a detailed account of species occurrence and associations. Moss has recently extended this work (3, 4). He has made an im-pressive contribution to fundament-al botanicfundament-al knowledge, facilitating a reasoned conception of species re-lationship. However, a comprehen-sive definition of muskeg was not attempted (understandably) and the literal interpretation of the ex-pression - "grass.,! bog" (5)-provided the only definition until the writer suggested the one pub-lished in 1952 (5, p. 10):
"Muskeg has become the term designating organic terrain, the physical condition of which is gov-erned by the structure of the peat it contains, and its related mineral sub-layer, considered in relation to topographic features and the sur-face vegetation with which the peat co-exists".
This definition is of necessity complicated in that an attempt was made to include the essential terms which those who work with muskeg find themselves discussing. Muskeg is not simply matter, though it con-tains material elements; it is in part a conception embodying the manifestation of conditions and states controlled primarily by the accumulation of peat (the maj or element) over areas of varying
ex ex ex ex
-*Department of Biology,
McMas-ter University, Hamilton, Onto
(2) For references see end of pap-er.
tent. This complexity is the chief reason for lack of understanding.
Perhaps the shortest and most used reference term for muskeg is 'Organic Terrain' (5). An objec-tion might arise through an ap-parent departure from the stated definition, which alludes to the min-eral sub-layer. This objection might be erased with the acceptance of a claim that the organic over-burden, not the substratum, direct-ly or indirectly controls the total assemblage of terrain conditions.
Our limited knowledge of organic terrain, in one sense a new kind of terrain, coupled with recent indus-trial development in relatively lit-tle known parts of Canada, have provided thc foundation for new engineering experience. Foundation problems relative to this terrain re-quire special consideration. The normal procedure of soil sampling and testing which precedes maj or construction of all types is no longer adequate if best engineering standards are desired. The usual transport, and often road construc-tion techniques, no matter how ela-borate, are at best precarious when prescribed for organic terrain.
\Vhere mineral soils predomin-ate, engineering accomplishment can be expected with the application of the directives that analyses and the best professional judgment can afford. For organic terrain, the lat-ter are largely lacking.
In correcting for this situation. it is perhaps well to emphasize in our thinking that, as for mineral soils so it is for peaty soils -guidancc comes from an understand-ing of thc structure of the soil me-dium. Differences in natural syn-thesis existing for peaty soil as compared with mineral soil should not discourage the investigator. The mineral soils, in the particulate sense, often originate from afar, as'
semble by chance arrangement, and are often subjected to reassortment, certainly in terms of geological time. Peaty soils, on the other hand, usually arise ill situ, are controlled as to structure by an admixture of biological principles, and are less subj ect to reassortrnent.
Thus, in time, it !lIay become
easier to prescribe for engineering requirements relutive to organic ter-rain than for mineral terter-rain.
This has been the hope in provid-ing the approach for this investiga-tion, the specific requirement for which is access. It is probably the most significant and biggest problem at present entrusted to engineers and scientists interested in organic terrain. Somc of the significance lies in the fact that vast areas of Canada are overlain by organic ter-rain and it is here where lllany of our resources are a waiting exploita-tion.
:MI'SKEG CHARACTER
A superficial examination of or-ganic terraiu more than five or ten acres in extent made for the pur-pose of accounting for specific fea-tures usually leads to bcwilderment. To assist in relieving this situation the writer proposed a system of classification designed primarily for enginering needs (5). It is also in this account that the basis of or-ganization in muskeg is emphasized. Importance is given to the fact that the principal component - the or-ganic one - is made up of two maj or layers, both of which must he clearly understood before classi-fication and prediction of conditions can be achieved.
This principle must be corisid-ered if planning for access over the terraiu is contemplated for almost any type of field operation involv-ing both temporary and p-ermanent development.
-Figures 1 and 2.-Cover formulaeAEH and EH.
EH
AEH
throughout depth, though usually there are macroscopic differences discernable. On planes paralleling the surface there is evidence of strnctural change from place to place. Thus, a comprehensive assess-ment of the structnral properties of the dcad layer of organic material requires consideration in terms of three dimensions.
This inj ects another difficulty into the problem of structural inter-prctution that was not applicable for the living layer. A means of reference to structnral change in depth as well as arca had to be at-tempted. Also, whatever the system pany the formulae. and photographs
depicting three of the couunoner ones are shown in Figures 1, 2, and
3.
The Peat Layer
The accumulation of peat be-neath the living layer is in effect the fossilized remains of past gen-erations of vegetation. In the pro-cess of fossilization, biochemical ehange followed by chemical deteri-oration produced the peat body. It
varies in colour from gold to black depending upon depth from the sur-face and on other factors. Oc-casionally it is structurally simil.n
The Living Layer
To the untrained eye, the vege-tation covering the peaty accumula-tion is apparently disorganized. However, the plant ecologist can detect discrete associations of plant species (5) that often reflect local environmental conditions. In at-tempting to classify surface vegeta-tion for the purpose of indirect ref-erence to subsurface conditions, the writer utilized these natural cate-gorlcs, In this approach, species and groups of species were bested for indicator value.
Limitations to the approach were soon encountered. Thoug-h species could he prominent members of an association, this prominence held sometimes to the same, sometimes to a different, degree for different kinds of associations. Species and associations transgressed physio-graphic realms, Often species were transient in the local sense, and some associations seemed to be in-securel v established. I n certain areas, particularly south to the lati-tude 100 miles south of Fort Churchill, some species showed a tendency to wide distribution which made it difficult to assign them to auy association.
Chief'lv because of these diffi-culties it was decided to attempt surfaee cover classification on an-other basis, still retaining emphasis on natural relationship as depict-ing- organi7.ation (5). Species were considered according to structural (form) categories rather than gene-tic ones. Often scver al genegene-tically unrelated species constituted a 'form g-enus'. Also, the species con-tained in a given form category are not necessarily identical.
To construct the svstem of clas-sification, form was "interpreted in terms of stature, presence or ab-sence of woodiness, and, where nee-essa ry, shape and external texture. Nine classes of vegetation had to be constructed to account for all sig-nificant living components of the cover laver. Because it was rare that a single class existed alone in a given area, provision was made for combinations of classes, which were referred to by groups of class svmbols. The procedure used in designating these groupings (cover formulae) and applying them in survey is described elsewhere (.5).
Sil;ce the earlier work was com-pleted, experi,en('e has shown that the cover formulae listed in Table I are the ones commonly encount· ered in planning for access over or-ganic terrain. Descript.ions
accorn accorn accorn accorn accorn . / accorn accorn accorn accorn accorn
-TABLEI.-COVER CLASSIFICATION
DESCRIPTION
Trees. 15 feet or over with
I non-woody. leathery to crisp
, ground coverage
F1 Non-woody, grass-like clumps or patches with non-woody, low, velvety plants, often in continuous mats. HE Low. non-woody plants of
leathery texture in mostly continuous mats, with woody shrubs0-2 feet tall.
EH Woody shrubs0-2 feet tall with low. non-woody. leath-ery plants in mostly ccn-tinuous mats.
COVERAGE
I
FORMULAj_AH
AEH I' Trees. 15 feet or over, with
ground coverage of woody
"I shrubs0-2 feet tall and
non-woody, crisp. leathery mats.
.
-D 1 Woody shrubs. 2-5 feet tall. _ 1 _ -DBE Woody shrubs, 2-5 feet tall and trees 5-15 feet tall. with woody shrubs0-2 feet tall.
Figure 3.-Cover formula FI
FI
of classification that could he de-vised, it had to be correlated, if pos-sible, with that for the living lay-er. This would enable thc observer to extrapolate from surface fea-tures to hidden sub-surface organ-ization in his interpretation. In-deed, if this could not be achieved. thc engineering requirements could not be met.
Attempts to elucida te adequately thc nature and history of structural change through the organic terrain by reference to macrofossils either failed or were impracticable.
Attention turned to aconsidera-tion of the discrete microscopic con-stituents of the peat. These pr oved to have high index value, and, when considered in terms of occurrence and frequency at all depths. they
demonstrated a basis on which structural trcnds in the peat could be expected (5, 8). The microfos-sils used were largely pollens and Sp01"eS, most of which were likely to be of in situ origin. Hence, the relative influence of form - and thereforc contribution to structure over area - for thc most inf luen-tial plants constituting the peat could be appreciated.
Also, a workable degree of cor-relation can be expected between cover formulae depicting surface structure and the suh-surface organ-ization reflected in mit-rofoss il rcc-ords (6).
The structural history brought into evidence through the
microfos-sils gaTe meaning to the discerniblc macrofossils, which otherwise had questionable, and certainly limited, use fulness for sugg.esting organic terrain character for any position beyond the immediate one in which they were found.
Ho wcver , utilization of macro' fossils for direct field referencc is still important, particularly as an aid to engin.eering determinations. Accordingly, a system of classifica-tion has becn devised in which six-teen categories of peat structurcs are discernible on the macrostruc-tural basis. These, recognised in terms of woodiness and fibrosity, arc fully dcser ihcd by the writer elsewhere (8).
It is now possible to conclude that, since structure in the living laver and macrostructure in the dead layer are kcyed to thc same referencc (microfossil history), surface character for organic ter-rain can be indirectly correlated with sub-snrf'ace macrostructure.
There will be appreciation, how-ever, for the need to apply classi-fication aids derived from all sources of refercnr-c, surface and sub-surface. for extensive engineer-ing plannengineer-ing.
TIl(' Orrtunic-]linl'rul Contact La.'1l'r
Attention must he given also to the na ture of the coutuct plane be-tween the dead organic layer and the mineral sub-layer. In the far
north, this zone is usually sharp and shallow. In western muskegs and in those charucteriz ing thc Ca-nadian Shield, the contact plane is often diffuse and deep. The latter condition is common in Alberta north and west of Edmonton. Here it is troublesome in that it is satu-rated throughout. This feature makes it all the more important to interpret the organic layer ade-quately in order that maximum use is made of its potentialities to con-tribute to enginecring purposc.
The Mineral Sub-Layer
The peat laycr is not always un-derlain by clay, as is sometimes sug-gestcd. The medium beyond the con-tact zone varies from clay to coarse gra\·eI. Unfortunately, prediction of the type of mineral soil base cannot be made with complete ccr-taintv from examination of either the living or the dead organic lay-ers. However, it is known that, gen-erally, PI coverage marks the pre-dominance of clay to silt beneath it;
'AH
refers to' a predominantly sandy base, andEll
withAEH
suggcsts sand to gravel.
Physiography
Topographic change in organic terrain is Ii complcx subj ert, It llIay be viewed in tenus of maj or fea-turcs significant for great distances, say two to twenty miles or morc,
-TABLEII.-TOPOGRAPHIC FEATURES AND THEIR SIGNIFICANCE
5. -Closed pond Subsidence for most vehicles
Differential subsidence after end filling Track damage; track throwing-same vehicles
RELATIVE ACCESS POSSIBILITY
Very good
PATTERN
Marbloid ..
Meaning of Air-Form Patterns
TABLE111.-AIR-FORM PATTERNS,
5,000FEET
Dermatoid.. Good Stipploid . . . . Fair
Terrazzoid , Mixed (fair to very good) Reticuloid . Bad
4 to 8. It will be appreciated that the dermatoid condition is chiefly textureless and plane: a simple cov-ering lacking ornamentation (skin-like in the fundamental and literal sense). The stipploid condition seems to be constructed of closely applied dots. Terrazzoid shows a 'patch-work' quality, reticuloid a net-work, and marbloid a polished-marhle effect.
It will be appreciated that where-as air-form pattern for low altitudes could be assessed in terms of exact-ing detail (Table II), for high al-titudcs it can be evaluated only in terms of attributes with broader meaning. In other words, patterns for high altitude might embrace several of those characterizing low altitudes. It is because of this that little of interpretive significance could be achieved for high altitude were it not for the faet that analy-tical investigation has established relationship between low and high altitude pattern.
To demonstrate the situation, Table IV has been included. Com-Vehicle tipping, load shifting
Immobility danger
SIGNIFICANCE
Frequent abrupt elevation Vehicle tipping. load shifting Ineffective mobility
See3
Very rough travel Track damage Immobility danger
Anchorage fer extracting vehicle Travel route. if wide enouvh for vehicle May cont. in hidden boulders
Indicates area drainable
TOPOGRAPHIC FEATURE
I-Ridge
7, -Polygons
2-Cc·vered rock enck.sure
4. -Peat plateau (irregular)
6. -Pond margin abrupt 3.-Peal plateau (even)
ual. Ground conditions form visual patterns which, when viewed from the air, are not readily discernible in that they merge to form new pat-terns of another order of signi
fi-cauce r.equiring re-interpretation. Finally, air photos taken at low al-titudes are rare, and usuallv the only photographic records'avail-able relatc to altitudes of the order of 17,000 to 30,000 feet.
Air-Form Patterns, 30,000 Feet Air-Form Pat.terns, 1,000-,5,000
Feet
In the writer's account of aerial interpretations dealing with alti-tudes up to 1,000 feet (10). ground-form pattern (i.e., form seen at ground level) was correlated with air-form patterns. It is between altitudes 1,000 and 5,000 feet that experience with the lower altitude air-form changes. Fortunately, the new order of definition can also be appreciated from 30,000-foot records. Itis becoming evident that, at the latter altitude, new experi· ences arise which, when studied, be-come useful in large-scale mapping, hut for problems of access (e.g.,
route selection) the patterns com-ing into prominence at .5,000 feet are the pradical ones for refer, cnce.
There are five of these patterns. N ames proposed for identifying them are listed in Table III.
In order to dcmonstrutc that dif-ference in air form over muskeg at high altitude is discer ni ble, photo-gra phs of each pattern named in Table I II are supplied in Figures
DIFn:RENTATION OF ORGANIC TER-RAIN PROPERTIES IN AIR SURVEY
or it may be considered with refer-ence to short distances of scvernl yards or less. Perhaps knowledge is sought of surface features promoted by the properties of the peaty and living layers as these have accumu-lated, or perhaps information is re-quired on sub-surfac-e features im-posed through the influence of the mineral foundation. Often, in the north. suh-surf'ace ice formations alone are responsible for provision of topographic variation.
Whatever the circumstances. characteristic topographic eonrli-tions a bound. The kinds of features have been described elsewhere (5). They have been listed as cor-related with vegetal factors in con-nection with the low altitude inter-pretation study published in 195,5
(10).
Their importance cannot be over-em phasized because they arc some-times easily detected from the air and data on their presence facilitate terrain analysis for applied work.
Where they are difficult to detect. they can often be predicted hy ap-plying the suggestions already made
by the writer (lac. cit., p. 13). 'Terrain contour change features most troublesome for over-muskeg travel are listed in Table II. Others that are not listed should not be neglected in terrain character pre-diction hccause they may have sig-nificance in an indirect way. Ｇｾｩｗ
ger-hcads: the common expression for 'hummocks' (lac. cii., p. 13. 17). are important indices of ter-rain saturation and poor summer drainage. They mark the position of ra pid recession of th.e ice level as spring thaw commences.
The accumulation of data has purpose and order only when' de-rived or secured in accordance with an understanding of the principles on which organic terrain organiza-tion is based. The technique for obtaining the data neeessary for in-terpretation is therefore important. Because only small percentages of several kinds of terrain can bear traffic (sometimes 25 per cent or even less}, the data are obviously often difficult to procure.
Of all terrain types, perhaps or-ganic is most likely to require sur-vey from the air in advance of op--erations. Howevcr , there arc three chief difficulties. Onlv the surfaee of the terrain can he ｾ･ＨＬｵ frOID the air, or from air photos, and there-fore procurement of sub-surface de-tails is interpretive rather than
vis-PIG.
4
DERMATOID
Fl
G.
.5
STIPPLOID
TABLEIV.-AIR-FoRM PATTERNS, HIGH ALTlTIJDE
PATTERN DESIGNATION
Dermatoid ... FI, HE, EH
Stipploid HE, D, FI, AEH, AH Terrazzoid FI, EH, HE, D, AEH,
DBE,AH Reticuloid. .. FI, EH, D, DBE M.arbloid.... AH. AEH, EH, DBE, HE,
FI
position of surface coverage in col-umn 2 shows that a given vegeta-tion cover formula may character-ize more than one kind of air-form pattern. The cover formula
FI,
for example, may occur in all five pat-bern types. However, differentia-tion of character is not difficult hecauseFI
would occur in different proportions and distribution for each pattern type. For the examples shown in Figures 4 to 8.FI
is very prominent in recticuloid, less so interrazzoid, less in siip ploid, less still in dermatoid, and least in
mar-bloid , This relationship, determined
hy analysis, is the usual one. The information is deri ved through com-parison of air-form features char-acterizing
FI
coverage for low al-titude with known cases for highFIG.6
TERRAZZ01D
Figures 4 to B.-Air.form photographs taken at 17,000 feet.
altitude and relating to the results physiographic features that can be observed from inspection of the high-altitude photos.
The frequency and distribution of coverage has been suggested as having index value for topographic character (10, cf. Table I). Thus,
wherever coverage is established for high-altitude pattern, topographic conditions can be suggested. This can be supported from comparison of low and high altitude records of known ground conditions.
Also. it is now possible to relate high-altitude pattern to sub-surface macro-structure. This is achieved by applying the analysis procedure, also shown in the handbook for low altitude (10, Table II).
It will always be the case that hest interpretive results of subsur-face conditions will be attained when microfossil analysis is includ-ed in the investigation (8, pp.
60-65).
However, that enough interpre-tive data on sub-surface organic ter-rain structure can be derived to prescribe for high-altitude air-form pattern now seems to be conclusive This has provided the approach for access studies over organic terrain that in many cases has not been seen except from 30,000-foot altitudes.
AERIAL INTERPRETATION FOR TRAFFICABILITY
If results of aerial interpretation are to assist in achieving access over organic terrain, the properties char-arterizing cover, topography, and suh-surf'ace detail will have to be translated into terms appropriate to trafficability. Information as gen-eral as that provided in Table
III
is inadequate.
5
-riG.
7
RETICULOID
nc.
8
MARBLOID
Terrain-Vehicle RelationsIt is obvious that successful ve-hicle performance and field effec-tiveness are going to be markedly limited hy the properties of muskeg. Yet it is not the case that vehicle development has paralleled adequate knowledge of muskeg conditions. Had this been so, not only might simple access difficulties have been obviated but transp-ortation with pay-load might have been a regu-larized performance
by
now. The first prerequisite to manoeuverlng over muskeg, then, is to recognize that success in transport can be ex-pected only if mechanical require-ment is developed in accordance with the complete range of organic terrain character. (ct. Table II, Col. 2).The Proximal Interpreted
Characteristics
The next prerequisite is to de· fine the characteristics of the or-ganic terrain (known through the results of aerial interpretation and other sources where possible) in terms that anticipate actual passage of the vehicle or vehicles. Route di-rection can be laid down by intelli-gently applying the results of aerial survey. Passage over the route is better delayed until it is known how frequently it is going to be
neces-TABLE VI.-ULTIMATE FEATURES AFFECTING TRAVEL POSSIBILITIES TABLE V.- TEST ANALYSIS AT 30,000 FEET
6 6 3 6 2 RESISTANCE BUOYANCY TO SHEAR INCIDENCE 8 7 9 4 9 4 9 7 7
Once trafficability problems have heen solved, implementation of op-erational planning can commence.
The Field Objectives
There are many types of opera-tion necessitating over-muskeg transport. In applying the princi-ples developed in this account it will be appreciated that, for access planning, the purpose of the op-eration should be kept in mind, es-pecially when final details of in-terpretation are being sought.
Pur-ApPLICATION OF PRINCIPLES FOR
FIELD OPERATIONS
slipes arc linked to a steel cable laid over the terrain by the lead vehicle (9).
Contemplation of the combina-tions of terrain properties leads one to the view that different kinds of vehicles and systems of operation could be devised. Whatever the de-sign, and whatever mechanical re-lations are expected for purposes of continuous access, low ground-pres-sure is not the only attribute re-quired. Maximum contact area, with tracks designed to give greatest tractive effort with minimum embar-rassment to low shear resistance, are other features. These relate to nat-ural mat construction in the peat. Buoyancy with adequate drawbar pull, and the ability to cross both open water and saturated granular peat where shear failure is inevit-able, are other fundamental ve-hicle requirements.
I
VEGETATION
I
SUB-SURFACEI
HINDRA.'\lCE ICE ROUGHNESS
1--
5-1--4---1-
'5-I
6 !I
2 2 2are the ultimate or elemental fea-tures, and are functions of sub-sur-face structure. Ratings for these factors are sometimes considered separately from the proximal ones (Table VI). They apply for the mik sample dealt with in Table V. It is unlikelv that the vehicle would make
ｴｨｾ
last quarter mile of the journey under these circum-stances unless it could be made buoyant in open fresh water. With a diffuse and fluid contact plane separating organic from mineral sub-layers, a condition which is highly probable, the vehicle and load would almost certainly disappear from sight.Vehicle Requirements
This being the case, the problem reverts to a consideration of vehicle design and route improvement. Lit-tle need be done in thc latter con-nection if the vehicle is huoyant, is steerable, and can propel itself to the next woody fibrous mat where tractive effort can be re-gained. Even under the more fav-ourable terrain conditions, if ground prcssure exceeds 0/2 lb.z'sq. in.2
,
partial subsidence can be expected. Provision for pulling loads and ex-tracting 'bogged-down' vehicles un-der worst terrain conditions is es-sential. To achieve this, a capstan-typc winch is desirable on the lead vehicle. A new system of transport employing power-driven 'barge'-shaped conveyances known as 'slipes' is now being proposed. The
I.-D.. 7
2.-DBE... 9
3.-DBE... 9
4 . - F I . . . 2
I
RESISTANCE COVER FORMULA TO COMPRESS'N 4.-FI in Reticu-loid ... 3.-DEB in Mar-bloidI
_ｃｏｖｅｒｆｾｾｾｕｌａJ
ROUTE DEVIATION I.-DinStipploid . 2 2.-DBE in Mar-bloid ....The reason for the apparent ano-maly is that resistance to vertical r-ornpresslon, resistance to shear, and buoyancy incidence (relative need for completely buoyant vehicle) have not yet been considered. These sary to change direction within the strip of terrain selected for pas-sage. \Vhat are the obstacles that will limit the efficiency of the op-eration? At how many points on the route will access become critical?
To offset the difficulties suggest-ed in these questions, the general or proximal characteristics are pro-dded.
With the hest mechanical facili-ties assumed to be available for travel, Route Deviation Rating is
evaluated as one of the proximal characteristics. If deviation is ex-pcctcd to render trufficability near-ly impracticable. the rating is arbi-trarily set at 10; if n,egiligihle it is 1. It is usually easy to suggest what the rating is within the range when the terrain properties have been adequately analysed.
The same ohtains for Resistance to Passaqe, at least in principle. Estimating is a little more complex however. in that ratings are provid-ed for vegetation hindrance, sub-surface ice interference, and terrain roughness. If trcc cover is dense to the point of being limiting, vege-tation hindrance rating is 10. If ice knolling is near limiting, sub-sur-face ice rating is 10. I f irregular peat plateaus nearly prevent pas-sage. roughness rating is 10. \Vhen these factors are effecting mini-mum influence the ratings will re-duce to unity for each case. I f these ratings, and that for route- devia-tion, exceed 80 per cent on the total, access is interpreted as critical, which infers that, at frequent in-tervals, passage will be almost im-possible.
Yn a test case of one mile of muskeg for which analysis was made from 30,000 fcet for each quarter-mile, the proximal character values shown in Table V were pro-vided.
It is easy to become over con-fident from these results for the middle two quarter-miles, where travel possihilities are apparently worst and 50 per cent effectiveness is expected. This would probably obtain in practice. However, the last quarter mile, apparently with best conditions and having about 80 per cent effectiveness expected, would in practice turn out to be the worst.
The Ultimate I nterpreied Characteristics
ACKNOWLEDGMENTS
The National Research Council Associate Committee on Soil and Snow Mechanics, through financial assistance shared with the Defence Research Board (Geophysics), have made it possible for the author to assemble the data essential for the writing of this paper. Acknowled-ment is gratefully made. l\Ir. R. F. Legget, Chairman of the Associate Committee on Soil and Snow Me-chanics, inspired the muskeg investi-gations ten years ago. To him I shall always be indebted. Mr. Alex Hemstock, Vice-Chairman of the Canadian Petroleum Association Muskeg Committee, has kindly fa-cilitatcd inspection of pertinent muskeg conditions prevalent in cer-tain oil fields in Alberta. Miss Jean Evel assisted directly in the as-sembling of data appearing in the text. Hcr co-operation is greatly ap-preciated.
pose of the operation has a bearing on route selection. An example of this is found in spacing techniques (1) applied in the exploitation of oil in a given field. Here geometric design tends to control permanent access routes.
For petroleum surveys, wherever muskeg interferes with normal op-erations, the following; primary steps lcading finally to exploitation are suggested:
I.-For Exploration
(a) Using air photos (low alti-tude if possible). plot thc best sys-tem of summer access routes that drilling requirements and transport of heavy equipment will allow.
(b) Define the proximal and ul-timate iuter prete.l characters (cf.
p. 477). Derive these for each quar-ter mile of access route.
(c) Determine (from air-survey records) the position of aggrcgate
(if
any) for back and end filling in road construction in anticipation of permanent operations.(d) Determine where cable
lay-ing will be required for critical ac-cess.
(e) Procure detailed structural information for organic terrain where drilling sites are specified, and where other installation is pro-posed.
(f) Where haulage of rigging is planned, analyse the tcrrain for pre-dominance of FI coyer formula for later application of the slipe-haul
system (9).
If
the latter is not con-templated, utilize D,DEE,
andEH
for haulage access.
2.-For Estahlishing Operations
(a) Utilize air-survey, laboratory, and other interpretive procedures to estahlish and map the hest geo-metric pattern for multiple passage traffic and anticipated road con-struction.
(b) If possible, plan for alterna-tive routing.
(c)
Locate local sources of cordu-roy and brush (important for arti-ficially strengthening matting in road foundations). Estimate the resources from air-survey records. Cover classes (5) Band D are best for this.(d) Designate the kind of over-muskeg road construction. The slipe-haul system may be of some assist-ance where road construction is im-practicable. Differentiate informa-tion, on maps and in the field, by colour schemes appropriate to the
different types of construction nee-essitated.
Conditions for Summer Operation
In exploration for and
develop-ment of the oil field it is to be ex-pected that organic terrain condi-tions will change in the course of the summer. In the early part, sub-snrfacc ice patterns will become manifest, and surface water will accumulate. Topography will there-fore probably become more difficult as the carlv summer works advance.
If routes 'sclected are to be used more than once this will promote route drainage change, and deteri-oration of structural properties of
the dead organic layer.
Seasonal Change
Where amorphous granular and fine fibrous non-woody peat mats exist, tractive effort becomes neg-ligible beforc ice recedes very far into the terrain. This condition is apt to persist in the spring for sev-eral weeks, and vehicles are inae-tivatcd, In autumn, thcse areas are often inundated. Under these cir-cumstances, planning for access should include provision for side traverse through more favourable muskeg with better mat structure.
IMPLEMENTATION OF OPERATIONAL PLANS
Extensive planning for summer access over organic terrain affords the best means of effective opera-tion. Much of it, even aerial inspec-tion, can be accomplished in win-ter. Field development can then pro-ceed with minimum loss of money and man-hours. It is more essential to analyse the terrain properties adequately; and to complete route planning, than it is to try to achieve access bv methods of trial and er-ror. The' latter will almost certain-ly lead to operational difficulties infinitely more expensive than those which may arise in implementation of planned routes.
Co-ordination of Interpreted Results
The construction of data sheets designed according to the nature of the operations contemplated, and providing information to facilitate future change in plans (e.g., re-routing) are essential, Where routes are planned it is suggested that pertinent data he transferred in summary form to route maps marked off in' quarter-mile intervals in order that spacc relationships can be examined as ficld data are be-ing assessed.
7
-(1 ) (2) (3)(4)
(5)
(6)(7)
(8)(9)
(10) REFERENCESHEM STOCK. A., Economic As-pects of Muskeg with Respect to Oil Production; Proc. Tech.
Sess. 3rd Ann. Meet Sub-Com. Muskeg N.R.C.. Tech. Mem.
(A.G.S.S.M.)
LEWIS, F. J .. and DOWDING, E.
S.. The Vegetation and Retro-gressive Cluin.qe» in Peat Area8 ("Mu8keg8") in Central AL-berta; Jour. Eco!., Vol. XIV. No.2. Aug., 1926.
Moss. E. H., Marsh and Bog Vegetation in Northwestern AL-berta; Can. Jour. Bot., Vol. 31,
July, 1953, pp. 448-470.
Moss, E. H., The Vegetation of Alberta; Bot. Rev., Vol. 21, No.9, Nov., 1955.
RADFoRTH, N. W., Suggested Classification of Muskeg for the Eng'ineer; Eng. Jour., Vol,
35, :pp. 1-12, 1952.
RADFoRTH N. W., The Use of
Plant Material in the Recogni-tion. of Northern 010g anic
Ter-rain Characteristics; Roy. Soc.
Can., Trans., Ser. III, Vol. 47, Sec. V, 1953,pp. 53-71.
RADFoRTH, N. W.,
Palaeobotan-ial Method in the Prediction of Sub-Surface Summer Ice Con-ditions in Northern Organic Terrain; Roy. Soc. Can.,
Trans., Ser. III, Vol. 48, Sec. V, 1954 pp. 51-64.
RADFoRTH, N. W., Range of Structural Variation in Or-ganic Terrain; Roy. Soc. Can.,
Trans., Ser. III, Sec. V, Vol. 49, 1955, pp. 51-67.
RADFORTH, N. W., and CUTH-BERTSON, J., The Slipe-Haul System for Over-M1lskeg Ac-cees ; (manuscript).
RADFoRTH, N. W., Organic Ter-rain Organization from the kir (altitudes less than 1,000 feet); Handbook No.1, De-fence Research Board, Dept. Nat. Defence, DR No. 95, 1955.
(Reprinted from The Canadian Mining and Metallurgical Bulletin, Jul«, 1956)
