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Chapter 2
2005 Geologic Assessment of Undiscovered Oil and Gas Resources,
Hanna, Laramie, and Shirley Basins Province, Wyoming and
Colorado
By Thaddeus S. Dyman and Steven M. Condon Volume Title Page
Chapter 2 of Petroleum Systems and Geologic Assessment of
Undiscovered Oil and Gas, Hanna, Laramie, and Shirley Basins
Province, Wyoming and Colorado
By U.S. Geological Survey Hanna, Laramie, and Shirley Basins
Province Assessment Team
U.S. Geological Survey Digital Data Series DDS–69–K
U.S. Department of the Interior U.S. Geological Survey
-
U.S. Department of the Interior DIRK KEMPTHORNE, Secretary
U.S. Geological Survey Mark D. Myers, Director
U.S. Geological Survey, Reston, Virginia: 2007
For product and ordering information:
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about the Earth, its natural and living resources,
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World Wide Web: http://www.usgs.gov
Telephone:1–888–ASK–USGS
Any use of trade, product, or firm names is for descriptive
purposes only and does not imply endorsement by the U.S.
Government.
Although this report is in the public domain, permission must be
secured from the individual copyright owners to
reproduce any copyrighted materials contained within this
report.
Suggested citation: Dyman, T.S., and Condon, S.M., 2007, 2005
Geologic assessment of undiscovered oil and gas resources, Hanna,
Laramie, and Shirley Basins Province, Wyoming and Colorado: U.S.
Geological Survey Digital Data Series DDS–69–K, chap. 2, 62 p.
ISBN 1-4113-2020-8
http://www.usgs.gov/pubprodhttp://www.usgs.gov
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iii
Contents
Abstract ……………………………………………………………………………………… 1
Introduction …………………………………………………………………………………… 1
Purpose and Scope …………………………………………………………………… 1
Data Sources ………………………………………………………………………… 7
Acknowledgments …………………………………………………………………… 7
Structural Setting …………………………………………………………………………… 8
Stratigraphy…………………………………………………………………………………… 10
Production Characteristics …………………………………………………………………… 20
Assessment of Oil and Gas Resources ……………………………………………………… 23
System for Numbering Assessed Resources ………………………………………… 23
Links to Data Input Forms and Graphical Data ………………………………………
24
Data Input Forms ………………………………………………………………… 24
Graphs of Exploration and Discovery Data for Conventional
Assessment Units … 24
Phosphoria Total Petroleum System ………………………………………………………… 24
Source Rocks ………………………………………………………………………… 24
Source Rock Thermal Maturity ……………………………………………………… 27
Hydrocarbon Migration ……………………………………………………………… 27
Reservoir Rocks ……………………………………………………………………… 28
Traps and Seals ……………………………………………………………………… 28
Tensleep-Casper Conventional Oil and Gas Assessment Unit
(50300101) …………… 29
Estimated Resources ……………………………………………………………… 29
Mowry-Hanna Composite Total Petroleum System ……………………………………………
31
Source Rocks ………………………………………………………………………… 31
Source Rock Thermal Maturity ……………………………………………………… 36
Hydrocarbon Migration ……………………………………………………………… 42
Reservoir Rocks ……………………………………………………………………… 42
Sundance Formation ……………………………………………………………… 42
Cloverly Formation ………………………………………………………………… 43
Muddy Sandstone Member of Thermopolis Shale………………………………… 43
Frontier Formation ………………………………………………………………… 43
Mesaverde Group ………………………………………………………………… 44
Lewis Shale ……………………………………………………………………… 44
Medicine Bow, Ferris, and Hanna Formations …………………………………… 45
Traps and Seals ……………………………………………………………………… 45
Mesozoic-Cenozoic Conventional Oil and Gas Assessment Unit
(50300201) ………… 46
Estimated Resources ……………………………………………………………… 46
Hanna Basin Continuous Gas Assessment Unit (50300261)
…………………………… 46
Niobrara Total Petroleum System …………………………………………………………… 46
Source Rocks ………………………………………………………………………… 49
Source Rock Thermal Maturity ……………………………………………………… 50
Hydrocarbon Migration ……………………………………………………………… 50
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iv
ReservoirRocks ……………………………………………………………………… 50 TrapsandSeals
……………………………………………………………………… 50
NiobraraContinuousOilAssessmentUnit(50300361)………………………………… 51
EstimatedResources …………………………………………………………… 51
NiobraraBiogenicGasTotalPetroleumSystem……………………………………………… 51
NiobraraBiogenicGasAssessmentUnit(50300461) ………………………………… 53
Hanna-MesaverdeCoalbedGasTotalPetroleumSystem …………………………………… 53
SourceRocks ………………………………………………………………………… 53
SourceRockThermalMaturity ……………………………………………………… 53
HydrocarbonMigration ……………………………………………………………… 55 ReservoirRocks
……………………………………………………………………… 56 TrapsandSeals
……………………………………………………………………… 56
MedicineBow–Ferris–HannaCoalbedGasAssessmentUnit(50300581) …………… 56
MesaverdeCoalbedGasAssessmentUnit(50300582) ……………………………… 56
ReferencesCited……………………………………………………………………………… 56
Figures 1.
MapshowingtheHanna,Laramie,andShirleyBasinsProvince,majortopographicand
geologicfeatures,subbasins,andborderingpetroleumprovinces………………… 3
2.
ColumnarsectionofstratigraphicunitsintheHanna,Laramie,andShirleyBasins
Province …………………………………………………………………………… 5 3.
MapofpartoftheHanna,Laramie,andShirleyBasinsProvinceshowingmajor
tectonicfeatures…………………………………………………………………… 9 4.
CrosssectionshowingtheArlingtonthrustandtheCooperCovefield …………… 10
5.
Generalizedcrosssectionshowingtrianglezonedevelopmentforstructuresinthe
HannaandLaramieBasins ………………………………………………………… 11
6.–19. PhotographsofrockunitsintheHannaBasin ……………………………………… 11
6. TensleepSandstoneoutcropinnorthernpartofHannaBasin ……………………… 11
7. GooseEggFormationoutcropinnorthernpartofHannaBasin……………………… 12
8.
BasalconglomerateofCloverlyFormationinnorthernpartofHannaBasin…………
13 9.
CloverlyFormation,ThermopolisShale,andMuddySandstoneinwesternpartof
HannaBasin………………………………………………………………………… 15
10. MowryShaleinwesternpartofHannaBasin ……………………………………… 15 11.
FrontierFormationalongUnionPacificRailroadincentralpartofHannaBasin
…… 16 12.
NiobraraFormationatSeparationFlatsinwesternpartofHannaBasin ……………
16 13.
SteeleShaleatSeparationFlatsinwesternpartofHannaBasin…………………… 17
14. HaystackMountainsFormationinwesternpartofHannaBasin …………………… 18
15. PineRidgeSandstoneinwesternpartofHannaBasin……………………………… 18 16.
LowerpartofLewisShaleinwesternpartofHannaBasin ………………………… 19 17.
SandstoneinMedicineBowFormationinnorthernpartofHannaBasin…………… 19
18. FerrisFormationincentralpartofHannaBasin …………………………………… 20 19.
HannaFormationincentralpartofHannaBasin …………………………………… 21 20.
MapofsouthwesternpartoftheHanna,Laramie,andShirleyBasinsProvince
showinglocationsofoilandgasfieldsandselectedpilotprojectsandwells
…… 22
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v
21. Map of Phosphoria Total Petroleum System showing limit of
distribution of Phosphoria
Formation source rocks ……………………………………………………………… 25
22. Events chart for Phosphoria Total Petroleum System in the
Hanna, Laramie, and Shirley
Basins Province ……………………………………………………………………… 26
23. Diagram of total sulfur in weight percent versus API gravity
for oil samples in the Hanna,
Laramie, and Shirley Basins Province ………………………………………………… 26
24. Map showing extent of the Tensleep-Casper Conventional Oil
and Gas Assessment
Unit …………………………………………………………………………………… 30
25. Map of the Mowry-Hanna Composite Total Petroleum System
showing the distribution of
Mowry-Hanna source and reservoir rocks in the Hanna, Laramie,
and Shirley Basins
Province ……………………………………………………………………………… 32
26. Events chart for the Mowry-Hanna Composite Total Petroleum
System in the Hanna,
Laramie, and Shirley Basins Province ………………………………………………… 33
27. Regional distribution of total organic carbon in the Mowry
Shale in the northern Rocky
Mountains and Great Plains …………………………………………………………… 34
28. Van Krevelen diagram showing oxygen index versus hydrogen
index of samples
collected in this study ………………………………………………………………… 34
29. Diagrams of transformation ratio versus time for the
Frontier-Hanna Formations in the
Hanna Basin …………………………………………………………………………… 37
30. Cross section showing one-dimensional burial history model
with transformation ratio
overlay for generation of oil near the center of Hanna Basin
………………………… 38
31. Cross section showing one-dimensional burial history model
with transformation ratio
overlay for oil-to-gas cracking near the center of Hanna Basin
……………………… 38
32. Cross section showing one-dimensional burial history model
with transformation ratio
overlay for generation of oil along the southern margin of Hanna
Basin ……………… 39
33. Cross section showing one-dimensional burial history model
with transformation ratio
overlay for generation of oil in Laramie Basin and Shirley Basin
……………………… 39
34. Map showing extent of Mesozoic-Cenozoic Conventional Oil and
Gas Assessment Unit … 47
35. Map of Niobrara Total Petroleum System showing distribution
of Niobrara Formation
source and reservoir rocks in Hanna, Laramie, and Shirley Basins
Province ………… 48
36. Events chart for the Niobrara Total Petroleum System in the
Hanna, Laramie, and
Shirley Basins Province ……………………………………………………………… 49
37. Map showing extent of the Niobrara Continuous Oil Assessment
Unit ………………… 52
38. Map showing extent of the Niobrara Formation in the Laramie
and Shirley Basins …… 54
39. Map showing outcrops of the Mesaverde Group and the extent
of the Medicine Bow
Formation ……………………………………………………………………………… 55
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vi
Tables 1. Characteristics of discrete and continuous oil and gas
accumulations ………………… 4 2. Assessment results summary—Hanna,
Laramie, and Shirley Basins Province (5030)…… 6 3. Oil and gas
production from formations that compose assessment units for
significant
fields in this study ……………………………………………………………………… 7 4. Depth
ranges of formation tops cut by wells in the Hanna, Laramie, and
Shirley Basins
Province ………………………………………………………………………………… 31 5. TOC and Ro
summary of new samples analyzed in this study …………………………… 35 6.
Burial history input parameters for wells used in the Hanna,
Laramie, and Shirley Basins
Province ………………………………………………………………………………… 40
Abbreviations Used in This Report AU assessmentunit BCFG
billioncubicfeetofnaturalgas BWPD barrelsofwaterperday CFGPD
cubicfeetofgasperday MMBNGL millionbarrelsofnaturalgasliquids MMBO
millionbarrelsofoil MMBOE millionbarrelsofoilequivalent Ro
vitrinitereflectance TPS totalpetroleumsystem USGS
U.S.GeologicalSurvey ft foot,feet Ga Giga-annum;billionsofyearsago
Ma Mega-annum;millionsofyearsago mi mile,miles m.y.
millionsofyears
Edited by Mary-Margaret Coates, Contractor, ATA Layout by Wayne
L. Husband, Contractor, ATA
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2005 Geologic Assessment of Undiscovered Oil and Gas Resources,
Hanna, Laramie, and Shirley Basins Province, Wyoming and Colorado
By Thaddeus S. Dyman and Steven M. Condon
Abstract
UndiscoveredoilandgasresourcesoftheHanna,
Laramie,andShirleyBasinsProvince,Wyomingand
Colorado,wereassessedin2005aspartoftheU.S.Geological
SurveyNationalOilandGasAssessmentProject.The
provincecontainsfivetotalpetroleumsystems:Phosphoria,
Mowry-HannaComposite,Niobrara,NiobraraBiogenicGas,
andHanna-MesaverdeCoalbedGas.Reservoirsasoldas
thePennsylvanianTensleepSandstoneandasyoungasthe
Paleocene-EoceneHannaFormationcomposethestratigraphic sequence.
Withinthesetotalpetroleumsystems,primarysource
rocksare(1)phosphaticshalesofthePermianPhosphoria
Formation;(2)shalesandcalcareousmudstonesofthe
CretaceousThermopolisandMowryShales,Frontierand
NiobraraFormations,andSteeleShale;and(3)coalsand
mudstonesoftheUpperCretaceousMesaverdeGroupand
MedicineBowFormation,UpperCretaceousandPaleocene
FerrisFormation,andPaleoceneandEoceneHanna
Formation.LacustrinemudstonesoftheFerrisandHanna
Formationsmaybeminorsourcerocksinthecentralpartof
theHannaBasin.
Oilandgasweregeneratedineconomicquantitiesin
differentpartsoftheprovinceatdifferenttimes,primarily
relatingtovariationsindepthofburial.Dataforthe
Thermopolis-Mowryintervalindicatethat(1)intheHanna
Basincenter,peakoilgenerationoccurredabout68million
yearsago(Ma)andoil-to-gascrackingoccurredabout
60Ma;(2)alongthesouthmarginoftheHannaBasin,
peakoilgenerationalsooccurredatabout68Ma,butno
appreciableoil-to-gascrackinghasoccurredtodate;and
(3)intheLaramieandShirleyBasins,sourcerocksdidnot
reachthermalmaturitiesnecessaryforsignificantoilandgas
generation.Mostoftheoilandgascurrentlytrappedinfields
intheLaramieBasinmigratedintolocalreservoirsfromthe
HannaBasinpriortoLaramidestructuralpartitioning.
Oilandgasmigratedfromsourcerocksintoreservoirs
throughasystemoffaultsandfracturesthatarepervasive
throughouttheareaandupdipalongbeddingplanesand
withinsandstoneunits.Trappingmechanismsinclude
structuresformedinitiallyinassociationwiththelate
PaleozoicAncestralRockyMountainsandlaterduringthe
LateCretaceoustoearlyTertiaryLaramideorogeny.Structures
maybethrustfaults,faultedanticlines,trianglezones,or
pop-upstructures.Stratigraphicpinchoutsandcombination
stratigraphic-structuraltrapsarealsocommon,especially
wheresedimentaryfacieschangeinreservoirrocks.Seals
consistofinterbeddedshalesandmudstonesanddiagenetic
cements.InsomeinstancesoilfromolderlatePaleozoic
structuraltrapsremigratedintoyoungerLaramidetraps.
SevenassessmentunitswereidentifiedfortheHanna,
Laramie,andShirleyBasinsProvince:(1)Tensleep-Casper
ConventionalOilandGas(50300101),(2)Mesozoic-CenozoicConventionalOilandGas(50300201),(3)Hanna
BasinContinuousGas(50300261),(4)NiobraraContinuous
Oil(50300361),(5)NiobraraBiogenicGas(50300461),(6)
MedicineBow-Ferris-HannaCoalbedGas(50300581),and
(7)MesaverdeCoalbedGas(50300582).Onlythreeofthese
assessmentunits(Tensleep-CasperConventionalOilandGas,
Mesozoic-CenozoicConventionalOilandGas,andNiobrara
ContinuousOil)werequantitativelyassessed;lackofdata
precludedassessmentoftheothers.
Totalmeanestimatedundiscoveredconventionaland
continuousresourcesinthesethreeassessmentunitsare94
millionbarrelsofoil,298billioncubicfeetofnaturalgas,and
14millionbarrelsofnaturalgasliquids.
Introduction
Purpose and Scope
Thepurposeofthisreportistopresenttheresultsofa
U.S.GeologicalSurvey(USGS)assessmentofundiscovered
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2 Undiscovered Oil and Gas–Hanna, Laramie, and Shirley Basins
Province, Wyoming and Colorado
oilandgasresourcesintheHanna,Laramie,andShirley
BasinsProvinceofsouth-centralWyomingandnorthern
Colorado(fig.1).Theprovincewasaffectedbytwomajor
crustalprocesses:bythedevelopmentofanearlyMesozoic
forelandbasinthatproducedalarge,asymmetricdepositional
troughintheWesternInterioroftheUnitedStatesandCanada
andbytheLateCretaceoustoearlyTertiaryLaramideorogeny
thatbrokeuptheintracontinentaldepositionalbasinand
formedavarietyofdiscretestructuralbasinsandbordering
uplifts.TheprovincecontainstheHanna,Laramie,andShirley
Laramidestructuralbasins(fig.1).
TheHanna,Laramie,andShirleyBasinsProvince
extendsfromtheRawlinsuplifteastwardthroughtheHanna,
Laramie,andShirleyBasinstotheLaramieMountains.Onthe
northandnorthwest,itisboundedbytheSweetwateruplift
andtheWindRiverBasin;onthesouth,itisboundedbythe
MedicineBowMountainsandSierraMadreuplift(fig.1).
Surroundingpetroleumprovinceshavealsobeenassessedfor
oilandgas—theWindRiverBasinProvincetothenorthwest,
theSouthwesternWyomingProvincetothewest,andthe
ParkBasinsProvincetothesouth(fig.1).Thisprovince
includesmostofCarbonandAlbanyCounties,Wyoming,
andthenorthernmostpartofLarimerCounty,Colorado.Its
areaencompassesmorethan4millionsquaremiles.Subbasin
names,suchasPassCreek,Kindt,Carbon,andCooperLake,
arecommonlyusedtoidentifyspecificgeologicareaswithin
theprovince(fig.1).
Variousoil-andgas-producingregionsoftheUnited
StatesarebeingreevaluatedasafollowuptotheUSGS’s1995
NationalAssessmentofUnitedStatesOilandGasResources
(Gautierandothers,1996);theresultsofthesestudiesare
availableathttp://energy.cr.usgs.gov/oilgas/noga/.Inthe
1995nationalassessment,theHanna,Laramie,andShirley
BasinsProvincewascombinedwiththeSouthwestWyoming
Province(Gautierandothers,1996;Law,1996).Becausethe
Hanna,Laramie,andShirleyBasinsProvincehadnotbeen
previouslyassessedseparatelybytheUSGS,estimatesof
undiscoveredresourcesfromthecurrentassessmentcannot
bedirectlycomparedwiththoseofpreviousUSGSestimates.
Law(1996)identifiedandassessedplaysthatlayinallorpart
ofthecombinedGreenRiver,Hanna,Laramie,andShirley
Basins.AnewassessmentoftheGreaterGreenRiverBasin
wasrecentlycompletedbytheUSGS(U.S.GeologicalSurvey
SouthwesternWyomingAssessmentTeam,2005).
AnotherdifferencebetweentheU.S.GeologicalSurvey’s
1995nationalassessmentandthisassessmentistheuseofthe
petroleumsystemmodel(MagoonandDow,1994).Atotal
petroleumsystem(TPS)isdefinedas“allgeneticallyrelated
petroleumthatoccurs,orisestimatedtooccur,inshowsand
accumulations,bothdiscoveredandundiscovered,whichhave
beengeneratedbyapodorbycloselyrelatedpodsofmature
sourcerock,”anditconsistsof“essentialgeologicelements
[that]controlthefundamentalprocessesofgeneration,
expulsion,migration,entrapment,andpreservationof
petroleumwithinthetotalpetroleumsystem”(Klett,2004).It
consistsofallareastowhichhydrocarbonsfromrelatedsource
rockspotentiallymigratedaftergenerationandexpulsion,and
itiscommonlydefinedbythegeographicextentofsource
andreservoirrocks.Acompositetotalpetroleumsystemisa
mappableentitythatisusedwhenmorethanonesourcerock
haschargedtheaccumulations(Klett,2004).
Assessmentunits(AUs)havereplacedplaysasthebasic
unitofassessment.Playswereidentifiedprimarilybyusing
similaritiesinpetroleumreservoirs,andsourcerockswere
notemphasized.Anassessmentunitis“amappablepartofa
totalpetroleumsysteminwhichdiscoveredandundiscovered
oilandgasaccumulationsconstituteasinglerelatively
homogeneouspopulationsuchthatthemethodologyof
resourceassessmentisapplicable”(Klett,2004).Itisathreedimensionalentity,consistingofacontiguousgeographicarea
andoneormoregeologicformations.TheuseofAUsrather
thanplaysdoesnotnecessarilyresultindifferencesinassessed
volumesofundiscoveredresources,butapplyingtheconcept
ofthetotalpetroleumsystemprovidesaunifyingframework
foridentifyingandanalyzingaccumulations(Klett,2004).
AsoneaspectofourstudyoftheHanna,Laramie,and
ShirleyBasinsprovince,welookedatthecharacteristics
ofknownandpotentialoilorgasaccumulationsto
determineiftheyarediscrete(conventional)orcontinuous
(unconventional)asclassifiedbySchmoker(1996),a
distinctionthatisbasedongeologicparametersratherthan
ongovernmentregulationsrelatingtoreservoirclassification.
Itisimportanttodistinguishbetweenthetwotypesof
accumulationbecausedifferentmethodsareusedforeach
typetoestimateundiscoveredresources.Severalfeatures
distinguishtheend-memberaccumulationtypes,although
aprobablecontinuumbetweenthetypescaninsomecases
makeclassificationdifficult.Twolistsofsuchdistinguishing
features(table1),weredrawnmainlyfromSpencer(1989),
Schmoker(1996),Wilsonandothers(2001),andLaw(2002).
OilandgasfieldsintheHanna,Laramie,andShirley
BasinsProvincewereevaluatedwithrespecttothe
characteristicslistedintable1.Mostexistingfields,which
lieonthemarginsoftheLaramieandHannaBasins,have
characteristicsthatclearlyclassifythemasconventional.
TwosmallNiobraraoilfieldsonthesouthflankoftheHanna
BasinweremodeledaftercontinuousNiobraraoilfields
intheSouthwesternWyomingProvince,andacontinuous
assessmentunitwasdefinedandquantitativelyassessedfor
Niobraraoil.Gasfieldshavenotyetbeendiscoveredinthe
deepcentralHannaBasin,andfewdeepwellshavebeen
drilledthere.Asaresult,adeep(>20,000foot(ft))basincentergasAUwasdefinedintheHannaBasinbutwasnot
assessed.AnevaluationofthefewdeepwellsintheHanna
BasinwasbasedondatafromWilsonandothers(2001).
Thegeochemistryofoilsamplescollectedfrom
Pennsylvanian,Jurassic,andCretaceousreservoirsinthe
LaramieBasinindicatesthatthesourceofsomefieldswasthe
PermianPhosphoriaFormation,andthesourceofotherswas
marineshalesofCretaceousandlowerTertiaryformations
(fig.2)(M.D.LewanandP.G.Lillis,USGS,writtencommun.,
2004).Rock-Evalpyrolysisdataindicatesource-rockpotential
-
Geologic Assessment—Undiscovered Oil and Gas—Hanna, Laramie, and
Shirley Basins Province, Wyoming and Colorado �
107° 106°
42°
41°
!(
!(
!(
!(
Hanna
Rawlins
Laramie
ROUTT LARIMERJACKSON
CARBON ALBANY
NATRONA
CONVERSE
17-2
0
+2000
+4000
+6000
-4000
-2000
-1000
-5000
-10000
+5000
+8000 -20000
-25000
-30000
+2500
+6000
0
+5000
0
-5000
-10000 -5000
+400
0
+600
0
-2000
+8000
+5000
0
+500
0
0
0
0
-1000
-200
0
+5000
+2000
+200
0
+6000
+5000
+6000
+4000
0
+200
0
+400
0
-2000
0
-10000
+6000
0
+5000
+2000
+2000
+4000
0
0
-5000
+2000
+200
0
-2000
+400
0
-5000
0
-5000
+5000
PC
BA
BR
BU
X Red Mountain
Figure 4 cross section
0 10 205 MILES
Sweetwater Uplift
Shirley
Basin
Laramie Basin
Hanna Basin Rawlins Uplift
Sierra Madre
Medicine Bow Mountains
Laramie Mountains
Wyoming Colorado
Kindt Basin
CLBCB
PCB
P B P
S W P
W R B P P R B P
Cheyenn
e belt
S W P
Wyoming
Figure 1. Hanna, Laramie, and Shirley Basins Province (outlined
in red), major topographic and geologic features, subbasins, and
bordering petroleum provinces. Contours are drawn on the top of
Precambrian basement in feet relative to sea level (modified from
Black-stone, 1989). Thick gray lines are major faults. Red
patterned areas are outcrops of Precambrian rocks from Green (1992)
and Green and Drouillard (1994). Green lines are seismic profiles
used to interpret subsurface structure for this assessment. CB,
Carbon Basin; CLB, Cooper Lake Basin; PBP, Park Basins Province;
PCB, Pass Creek Basin; PRBP, Powder River Basin Province; SWP,
Southwestern Wyoming Province; WRBP, Wind River Basin Province.
Green triangle—Anadarko Durante 17–2 well. Green filled circles—BA,
Coastal Bates Creek Cattle 1–18–28–79 well; BR, Brinkerhoff Hanna
Unit No. 1 well; BU, Buttes Federal 1–18 well; PC, Humble Pass
Creek Ridge No. 1 well. Location of the Cheyenne belt from Stone
(1995).
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� Undiscovered Oil and Gas–Hanna, Laramie, and Shirley Basins
Province, Wyoming and Colorado
Table 1. Characteristics of discrete and continuous oil and gas
accumulations.
[DistinguishingfeaturesfromSpencer(1989),Schmoker(1996),Wilsonandothers(2001),andLaw(2002)]
Characteristic Discrete (conventional)
Type of accumulation
Continuous (unconventional)
Sourcerocks
Maturity
Reservoirrocks
Potentiallydistantfromreservoirs
Accumulationscanoccurinimmaturerocks becauseofmigration
Sourcerocksnearreservoirs;migration distancescommonlyshort
Topsofaccumulationscommonlywithina
narrowvitrinitereflectance(Ro)rangeof 0.75–0.9percent
Sealsortraps Well-definedstratigraphicandstructuraltraps
Lacktraditionalsealsortraps
Porosity Goodreservoirporosity
Lowreservoirporosity,commonlylessthan13 percent
Permeability Goodreservoirpermeability
Lowreservoirpermeability(
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5 Geologic Assessment—Undiscovered Oil and Gas—Hanna, Laramie,
and Shirley Basins Province, Wyoming and Colorado
FORMATION/GROUP NAMES
HANNA, LARAMIE ERA PERIOD EPOCH AND SHIRLEY BASINS
NIOBRARA Fm SAGE BREAKS Sh
CEN
OZOI
CM
ESOZ
OIC
PALE
OZOI
CPR
ECAM
BRIA
N
QUATERNARY
TERTIARY
CRETACEOUS
PALEOCENE
EOCENE
OLIGOCENE
MIOCENE
PLIOCENE
PLEISTOCENE
HOLOCENE
JURASSIC
LOWER CRETACEOUS
UPPER CRETACEOUS
TRIASSIC
PERMIAN
PENNSYLVANIAN
MISSISSIPPIAN
DEVONIAN
SILURIAN
ORDOVICIAN
CAMBRIAN
PROTEROZOIC
ARCHEAN
METAMORPHIC
AND
INTRUSIVE
ROCKS
Ar Wh
Wb WIND RIVER Fm
HANNA Fm
FERRIS Fm
LEWIS Sh
STEELE Sh
MEDICINE BOW Fm
Mv
Gp
HM, AR
PR, AL
FRONTIER Fm
MOWRY Sh
THERMOPOLIS Sh
DAKOTA Fm LAKOTA Fm
MORRISON Fm
CLOV
ERLY
Fm
SUN
DAN
CEFm
CH
UGW
ATER
Gp
UPPER SUNDANCE
BASAL SUNDANCE
LOWER SUNDANCE
JELM Fm ALCOVA Ls
RED PEAK Fm
GOOSE EGG Fm
TENSLEEP Ss-CASPER Fm
EL DS FL GS ML OS
AMSDEN Fm FOUNTAIN
Fm
Md
Fh
Undivided
Undivided
PR
RR
Upper shale mbr
Muddy Sandstone Mbr
Skull Creek Sh Mbr
Figure 2. Columnar section of stratigraphic units in the Hanna,
Laramie, and Shirley Basins Province (modified from Harshman, 1972;
Love and others, 1987; and Stone, 1995). Fm, Formation; Gp, Group;
Ls, Limestone; Mbr, Member; Sh, Shale; Ss, Sandsonte. Fh, Flathead
Sandstone; Md, Madison Limestone; OS, Opeche Shale Member; ML,
Minnekahta Limestone Member; GS, Glendo Shale Member; FL, Forelle
Limestone Member; DS, Difficulty Shale Member; EL, Ervay Limestone
Member; MV Gp, Mesaverde Group; HM, Haystack Mountains Formation;
AR, Allen Ridge Formation; PR, Pine Ridge Sandstone; AL, Almond
Formation; RR, Rock River Formation; Wb, Wagon Bed Formation; Wh,
White River Group; Ar, Arikaree Formation.
-
Total petroleum Total undiscovered resources system (TPS) MAS
Prob. Oil (MMBO) Gas (BCFG) NGL (MBNGL)
and assessment (0-1) F95 F50 F5 Mean F95 F50 F5 Mean F95 F50 F5
Mean unit (AU)
Conventional oil and gas resources Phosphoria TPS
Tensleep–Casper Conventional Oil and Gas AU Oil accums. 0.5 6 19
39 20 6 18 42 20 190 650 1,590 740 1
Gas accums. 3.0 16 47 101 52 460 1,380 3,220 1,550
Total 1 6 19 39 20 22 66 143 72 650 2,030 4,810 2,290
Mowry–Hanna Composite TPS Mesozoic–Cenozoic Conventional Oil and
Gas AU
Oil accums. 0.5 7 31 79 36 17 75 208 89 1,620 7,320 21,610 8,910
1 Gas accums. 3.0 25 99 278 118 460 1,920 5,770 2,360
Total 1 7 31 79 36 42 174 486 207 2,080 9,240 27,380 11,270
Total undiscovered conventional oil and gas resources Oil
accums. 13 50 119 56 23 94 250 110 1,810 7,970 23,200 9,650
Gas accums. 42 146 379 170 920 3,300 8,990 3,910 Total 13 50 119
56 64 240 629 279 2,730 11,270 32,190 13,560
Continuous oil and gas resources Mowry-Hanna Composite TPS
Hanna Basin Continuous Gas AU—Not quantitatively assessed
Niobrara TPSNiobrara Continuous Oil AU
Oil accums. 0.5 14 33 76 38 6 16 43 19 0 0 0 0 1 Gas accums.
3.0
Total 1 14 33 76 38 6 16 43 19 0 0 0 0
Niobrara Biogenic Gas TPSNiobrara Biogenic Gas AU—Not
quantitatively assessed
Mesaverde–Hanna Coalbed Gas TPSMedicine Bow–Ferris–Hanna Coalbed
Gas AU—Not quantitatively assessed Mesaverde Coalbed Gas AU—Not
quantitatively assessed
Total undiscovered continuous oil and gas resources
Oil accums. 14 33 76 38 6 16 43 19 0 0 0 0 Gas accums.
Total 14 33 76 38 6 16 43 19 0 0 0 0
Total undiscovered oil and gas resources
Oil accums. 28 83 195 94 29 110 292 129 1,810 7,970 23,200 9,650
Gas accums. 42 146 379 170 920 3,300 8,990 3,910
Total 28 83 195 94 70 256 671 298 2,730 11,270 32,190 13,560
� Undiscovered Oil and Gas–Hanna, Laramie, and Shirley Basins
Province, Wyoming and Colorado
Table 2. Hanna, Laramie, and Shirley Basins Province assessment
results.
[MMBO,millionbarrelsofoil;BCFG,billioncubicfeetofgas;MBNGL,thousandbarrelsofnaturalgasliquids;MAS,minimumaccumulationsize
assessed(MMBOforoilaccumulations,BCFGforgasaccumulations);Prob.,probability(includingbothgeologicandaccessibilityprobabilities)ofatleast
oneaccumulationequaltoorgreaterthantheMASor,forcontinuous-typeresources,atleastoneadditionalcellequaltoorgreaterthantheminimumestimatedultimaterecovery;Accums.,accumulations.Resultsshownarefullyriskedestimates.Forgasaccumulations,allliquidsareincludedasNGL(natural
gasliquids).F95representsa95percentchanceofatleasttheamounttabulated;otherfractilesaredefinedsimilarly.Asinglemajorcommodityandits
coproductswereassessedforcontinuous-typeassessmentunits.Fractilesareadditiveundertheassumptionofperfectpositivecorrelation.Resourcetotals
maynotbeequaltothesumsofthefractilesormeansbecausenumbershavebeenindependentlyrounded.Totalsreflectroundingtonearestwholenumber.
Shadingindicatesnotapplicable]
-
Geologic Assessment—Undiscovered Oil and Gas—Hanna, Laramie, and
Shirley Basins Province, Wyoming and Colorado �
Table �. Oil and gas production from formations that compose
assessment units for significant fields in this study. Data from
Hollis and Potter (1984) and IHS Energy Group (2004a).
[Meandepth,averagedepthofperforationsforthereservoirinthelistedfield(*,perforationdatanotavailable;averagetotaldepth
calculated);MMBO,millionsofbarrelsofoil;BCFG,billionsofcubicfeetofgas(gasvolumeslessthan0.1BCFGroundedtozero)]
Discovery Mean Oil GasPrimary reservoir Field name year depth
(MMBO) (BCFG)(ft)
Tensleep-CasperConventionalOilandGasAssessmentUnit(50300101)
Tensleep AllenLakeEast 1950 3,944 0.6 0 Tensleep BigMedicineBow
1948 *6,838 0.2 0.1 Tensleep Herrick(Dome) 1947 3,654 1.1 0.1
Tensleep LittleLaramie 1948 3,740 1.3 0.1 Tensleep Quealy(Dome)
1947 5,414 5.3 0
Mesozoic-CenozoicConventionalOilandGasAssessmentUnit(50300201)
Sundance, Dakota Big Medicine Bow 1935 5,019 7.5 11.1 Dakota,
Muddy, Shannon Cooper Cove 1944 4,793 1.9 0.7 Lakota, Dakota, Muddy
Diamond Ranch 1957 5,410 1.1 0.2 Muddy, Shannon Dutton Creek 1926
4,775 0.3 0.2 Sundance Elk Mountain 1957 6,520 0.9 0 Sundance,
Dakota Quealy (Dome) 1934 3,324 5.3 0 Lakota-Dakota, Muddy, Rex
Lake 1923 2,726 1.0 0 Shannon. Sundance through Frontier Rock River
1918 3,021 50.0 11.5 Lakota, Muddy Seven Mile 1947 5,957 0.6 0
TOTALPRODUCTION 77.1 24.0
Data Sources
Primarydatasourcesforourassessmentarecommercial
databasesfromIHSEnergyGroup(2004a,b).Wellproduction
andcompletiondataarecurrentasofFebruaryandApril2004,
respectively.Productionandcompletiondataareavailable
fornearly600leasesfortheunitsassessedintheprovince,
anddatasuchasformationtops,drill-stemtests,andinitial
productiontestsforsome1,350wellshavebeenreported.
Anotherprimarysourceofgasandoilfieldandreservoir
datawasNRGAssociates(2003),whichprovidedinformation
onthedatesofdiscoveryandsizesofgasandoilfields,trends
ofincreasingordecreasingfieldvolumes,gas-oilratios,and
APIoil-gravityvalues(seechapterbyKlettandLe(2007)
(thisCD-ROM).Manypublishedpapersonthestructure,
stratigraphy,andpetroleumgeologyoftheregion,aswellas
discussionswithpetroleumindustrypersonnel,alsoprovided
importantinformation.
Acknowledgments
WethankDavidDudleyofDudleyandAssociates
fordiscussingcoalbedgasintheHannaBasin.Thomas
GriffithandDouglasHazlettofAnadarkoPetroleum,and
RogerMatson,consultingpetroleumgeologist,provided
insightsintodeepHannaBasinexploration.DonaldStone,
consultingpetroleumgeologist,wasespeciallyhelpfulin
identifyingstructuralrelationsintheLaramieBasin.E.
AllenMerewetherandWilliamPerry,Jr.,providedvaluable
informationonthestratigraphicandstructuralgeologyof
theregion.WeappreciatethehelpofMichaelLewan,Paul
Lillis,andMarkPawlewicz(USGS)fortheirworkonoil
sourcerocks,forgeneratingburialhistoryplotsforwellsin
thestudyarea,andfordiscussionsthathelpedtoresolvesome
ofthecomplexissuesregardinghydrocarbonsourcerocks.
TroyCookclarifiedthenatureofseveralgasaccumulations
intheHannaBasinbyusingproductioncharacteristics.We
thanktheassessmentteamofChristopherSchenk,Timothy
Klett,RonaldCharpentier,TroyCook,RichardPollastro,
andThomasAhlbrandt,whohelpedguideouranalysisand
calculatedthefinalresourceassessmentnumbers.USGS
contractorsChristopherAndersonsupervisedgeographic
informationsystemprocessingandpreparedworkingmaps,
andWayneHusbandpreparedfiguresandformattedthefinal
report.LawrenceAnna,JamesOtton,DouglasNichols,and
WilliamKeeferreviewedthemanuscript.
-
� Undiscovered Oil and Gas–Hanna, Laramie, and Shirley Basins
Province, Wyoming and Colorado
Structural Setting
TheHanna,Laramie,andShirleyBasinsProvince
experiencedacomplexstructuralhistoryhighlightedbymajor
tectoniceventsinthePrecambrian,latePaleozoic,andLate
CretaceoustoearlyTertiary.Thesetectoniceventsandstructural
styleshavebeendescribedindetailbymanyinvestigators,such
asBlackstone(1953,1965,1975,1983,1991,1993,1994,
1996),McGookeyandothers(1972),Stone(1984,1995,2002,
2005),KaplanandSkeen(1985),MerewetherandCobban
(1985),Hansen(1986),LeFebre(1988),LillegravenandSnoke
(1996),PerryandFlores(1997),Secord(1998),Wroblewski
(2003),andLillegravenandothers(2004).Abriefsummary
ofthestructuralhistoryoftheregionispresentedhere,drawn
largelyfromthesepapersandothersthatarecitedbelow.
Regionalstructuresthatwerecreatedwithinandadjacent
totheprovinceinPrecambriantimealsoinfluencedlater
tectonics.TheCheyennebeltofStone(1995),alsoknown
astheWyominglineament(Ransome,1915;Blackstone,
1953)ortheSybillelineament(MaughanandPerry,1983),
trendsfromtheSierraMadreandMedicineBowMountains
northeastwardthroughtheLaramieMountains(fig.1).The
featurehasbeeninterpretedasasuturezoneofmyloniticand
cataclasticrocksthatseparatestheWyomingandColorado
basementcrustalterranes.Rocksnorthofthisboundaryare
Archeaninage(greaterthan1.8billionyearsold(Ga)),whereas
rockssouthoftheboundaryareProterozoicinage(lessthan
1.8Ga)(Simsandothers,2005).Thissuturezoneisevidence
ofacollisionbetweenthepaleo-Proterozoicarcterraneofthe
ColoradoprovincewithArcheancratonicrocksoftheWyoming
province.Thecollisionoccurredabout1.8Gaanddeformed
andmetamorphosedrocksonbothsidesofthesuture(Sims
andothers,2005).Thepresenceofnumerousfoldsandfaults
inyoungerrockswithintheareaoftheCheyennebeltindicates
recurrentstructuralactivityduringthePhanerozoic.Within
theLaramieBasininparticular,laterLaramidedeformation
followstheestablishednortheast-directedtrendoftheearlier
Precambrianstructures.
MaughanandPerry(1983)describedasystemoflinear
structuralelementsinthenorthernRockyMountainregionthat
canbeidentifiedintheHanna,Laramie,andShirleyBasins
Province.Theprovinceliesattheintersectionofsixofthese
featuresthatmayhavehadtheiroriginsinthePrecambrian;
thesefeaturesaffectedsedimentarydepositionalpatternsand
faciesdevelopmentduringthePaleozoicandearlyMesozoic
(Blackstone,1993).
Asecondepisodeofregionaldeformationoccurredduring
thelatePaleozoic.ThesupercontinentPangeacoalescedduring
thePennsylvanianandPermianPeriodsandcausedacollision
betweentheAfrican,SouthAmerican,andNorthAmerican
plates.ThiscollisiondeformedPaleozoicrocksoftheOuachita
orogenicbeltandcausedcratonicdeformationasfarnorthas
ColoradoandWyomingthatculminatedindevelopmentofthe
AncestralRockyMountains(Kluth,1986).
TheaxisoftheAncestralRockyMountainsextended
northwestwardfromtheDenver,Colo.,areaintosouth-central
Wyomingobliquetothenorth-southaxisofthepresent-day
FrontRangeofColoradoandWyoming.Theancestralfeature
wascomposedofaseriesoftiltedandrotatedfaultblocks
thatsteppeddownwardalongitsnortheastmarginintoabroad
depositionaltroughofmarineandnonmarinesedimentsin
southeasternWyoming(MaughanandAhlbrandt,1985).This
deformationisreflectedinthePermianthrust-foldcomplex,
arotatedblockofnorth-tonortheast-trendingthrust-faulted
anticlineslyingnorthoftheCheyennebelt(Stone,1995).
Someoftheseanticlinesareassociatedwithoilfieldsinthe
LaramieBasinandhavebeenwelldocumentedonseismic
profiles.Seismicdatashowthatthrustfaultsterminateinthe
PermianGooseEggFormation,whichwasdepositedduring
developmentofthethrustfaults(Stone,1995).
Thethirdandmostprominentdeformationepisodeisthe
LaramideorogenyofLateCretaceoustoearlyTertiaryage
(DickinsonandSnyder,1978;Dickinsonandothers,1988).
Commonly,Laramidestructuressothoroughlyoverprinted
earlierstructuresthatmanybecamehiddenordifficultto
recognize.Today,theHanna,Laramie,andShirleyBasins
aredistinctstructuralbasins.PriortotheLaramide,however,
theywerepartofabroadforelandbasinthatincludedthe
entireHanna,Laramie,andShirleyBasinsProvinceandhad
contiguouseastward-flowingfluvialsystems.Thestructural
basinswereformedinthelatePaleoceneinconjunctionwith
thedevelopmentofbasement-coredupliftstothewest(Rawlins
uplift)andeast(FlatTopandSimpsonRidgeanticlines,fig.
3)(Lillegravenandothers,2004).AccordingtoWroblewski
(2003),theHannaandLaramieBasinstectonicallyseparated
duringthemiddlePaleocene(about58Ma),aneventassociated
withtectonicupliftalongthenorthwestmarginoftheLaramie
Basin.Dammingofthrough-flowingstreamsresultedina
widespreadlacustrinefaciesintheupperpartoftheFerris
FormationintheHannaBasin.
ThemodernHannaBasinisoneofthesmallestLaramide
structuralbasinsintheRockyMountainregionbutitisalsothe
deepest;itsmorethan40,000ftofbasinfillincludesmorethan
15,000ftofUpperCretaceousandlowerTertiarysynorogenic
sedimentaryrocks(fig.2).Thebasinisstructurallycomplex
andpossessesnumerousLaramidestructuresthatwereformed
duringatimespanofabout15m.y.TheLaramieBasin,larger
butnotasdeepastheHannaBasin,isalsostructurallycomplex,
particularlyalongitswestmargin.Historically,theLaramie
BasinhasproducedthemostoilandgasintheHanna,Laramie,
andShirleyBasinsProvince.
TheShirleyBasinisabroad,southward-plungingsyncline
boundedonthewestandsouthwestbytheShirley,Seminoe,
andFreezeoutMountains,ontheeastandnortheastbythe
LaramieMountains,andonthesouthbystructuresatthe
northendoftheLaramieBasinsuchasComoBluffandFlat
Topanticlines(fig.3).Inthisbasin,post-LaramideTertiary
sedimentsweredepositedonanerodedsurfaceofUpper
Cretaceousstrata.Laramide-agenormalfaultsdisplacerocksas
youngasLateCretaceous,butlarge-displacementthrustfaults
arerare.
-
5,000
107˚ 106˚30' 106˚
42˚
˚30'
0
0
0
0 0
0
0
0
0
0
0
5,000 5,000
5,000
5,000
5,000
-10,
000
-10,000
-30,000
-10,000?
TB
RU
SMA
PCA
CBA
FM
FTAST
AT
SWEETWATER UPLIFT
SHIRLEY BASIN
HANNA BASIN
LARAMIE
BASIN
SHIRLEY MOUNTAINS
ELK MOUNTAIN
SEMINOE MOUNTAINS
COOPER LAKE
BASIN
MEDICINE BOW
UPLIFT SIERRA MADRE
SIM
PSON
RID
GE
CARBON BASIN
CA
RB
ON
CO
UN
TY
A
LB
AN
Y C
OU
NT
Y
Rawlins
PM
5,000
5,000
5,000
LARA
MIE M
OU
NTA
INS
EXPLANATION
Thrust fault–Sawteeth on upper plate 0 10 20 MILES
Anticline—Showing direction of plunge
Syncline
Structure contour, in feet, above or below (-) sea level to
Precambrian rocks
41
Geologic Assessment—Undiscovered Oil and Gas—Hanna, Laramie, and
Shirley Basins Province, Wyoming and Colorado �
Figure �. Part of the Hanna, Laramie, and Shirley Basins
Province showing major tectonic features (modified from Perry and
Flores, 1997). AT, Arlington thrust fault; CBA, Como Bluff
anticline; FM, Freezeout Mountains; FTA, Flat Top anticline; PCA,
Pass Creek anticline; PM, Pennock Mountain; RU, Rawlins uplift;
SMA, St. Mary’s anticline; ST, Shirley thrust fault; TB, The
Breaks.
Gries(1983a)relatedthetiminganddirectionofregional
deformationeventsintheLaramideorogenytocontinentalscaleplatetectonicevents.Sheshowedthattheorientationof
Laramideupliftschangedthroughtimeowingtochangesin
theregionalstressfield,suchthatLateCretaceousstructures
trendnorth-south,Paleocenestructurestrendnorthwestsoutheast,andEocenestructurestrendeast-west.
IntheHanna,Laramie,andShirleyBasinsProvince,
LaramidestructurestypicallyarePrecambrian-coreduplifts
withboundingthrustsystemswheremountain-frontthrust
faultsoverrodebasinmargins,ortheyarethrust-faulted
anticlineswithbothinto-basin–andout-of-basin–directed
thrustfaultsthatformedpop-upstructuresortrianglezones
(Mountandothers,2004).Inaddition,someLaramide
faultshaveaconsiderablestrike-slipcomponentbecausethe
provincehasundergonerotation(Stone,1995).
TheRockyMountainregionhasnumerousexamples
ofPrecambrian-coredupliftsthatoverrodethemarginsof
deepstructuralbasinsalongthrustfaultswiththousandsof
feetofdisplacement.Thicksubthrustrocksequenceshave
thepotentialforundiscoveredoilandgasaccumulations
(Gries,1983b).TheShirleythrust,atthenorthmarginof
theHannaBasin,andtheArlingtonthrust(figs.3,4),along
thewestmarginoftheLaramieBasin,compriseextensive
subthrust(footwall)wedgesofsedimentaryrocksbeneath
shallow(hanging-wall)Precambrianrocks.TheShirleyand
-
Fig._4
10 Undiscovered Oil and Gas–Hanna, Laramie, and Shirley Basins
Province, Wyoming and Colorado
ArlingtonthrustshavelongandcomplexLaramidehistoriesof
Madre,MedicineBowMountains,LaramieMountains,
development(Stone,1995;Lillegravenandothers,2004).
LaramidedeformationintheHannaandLaramie
Basinsalsoinvolvedthin-skinned,out-of-basinthruststhat
placedyoungerrocksoverPrecambrianbasementandolder
sedimentaryrocksandformedtrianglezones(fig.5)(Erslev,
1991;Lillegravenandothers,2004).Theseout-of-basinthrust
systemsareassociatedwithfoldingofthethick(>15,000
ft)UpperCretaceousandlowerTertiarybasinfill.Out-ofbasinblindthrustsdisappearintoCretaceousshalesinmany
places,suchasthePassCreek,St.Mary’s,andSimpson
RidgeanticlinesinthesouthernpartoftheHannaBasin,and
“TheBreaks”atthenorthendofthebasin(fig.3;Hitchens,
1999).EarlyLaramidesyntectonicsedimentswereinvolvedin
laterLaramidedeformation,creatingacomplexdepositional
pattern(Blackstone,1993).
Precambrian-coredsatelliteupliftsborderthesouthend
oftheHannaBasinjustnorthoftheMedicineBowuplift
(Blackstone,1993).Theseasymmetricstructuresarebounded
bythrustfaultsandwereformedbyupliftofPrecambrian
coresandconcurrentfoldingofthelessbrittlesedimentary
coverrocks(McClurgandMatthews,1978).
Stratigraphy
NorthoftheCheyennebelt(fig.1),thePrecambrian
basementisanArcheanmicroplateofmetasedimentary
gneissandschistandgraniticrocks,olderthan2.5Ga,that
underliesmostoftheHanna,Laramie,andShirleyBasins
Province.TheserocksareexposedinthenorthernSierra
SW NE
Medicine Bow Mountains
Arling
tonthru
st
Cooper Cove field
1 MILE
T
Kmv - Kl
Km - Ks
J -
Km - Ks Kmv - Kl
T
�
� � �
�
�
7
5
3
1
0
–1
Figure �. Generalized southwest-northeast cross section showing
the Arlington thrust fault and the Cooper Cove field in the western
Laramie Basin. Simplified from Stone (2005). Location of cross
section shown on figure 1. pe, Precambrian; J-e, Jurassic through
Cambrian ; Km-Ks, Cretaceous Muddy Sandstone Member through
Cretaceous Steele Shale; Kmv-Kl, Cretaceous Mesaverde Group through
Cretaceous Lewis Shale; T, Tertiary rocks undifferentiated.
Vertical scale in thousands of feet. No vertical exaggeration.
andSweetwateruplift(fig.3).SouthoftheCheyenne
belt,thePrecambrianbasementrocksconsistofa1.8-Ga
metamorphicterraneintrudedby1.5-to1.4-Gagranitic
rocks(Petermanandothers,1968).Metasedimentaryand
metavolcanicgneissesandcalc-alkalicplutonicigneous
rocksareexposedinportionsofthesouthernMedicine
BowandSierraMadreuplifts(Houston,1968;Simsand
others,2005).Precambrianplutonicandmetamorphicrocks
areoverlainbyanunconformitybyCambrianandyounger
sedimentaryrocks.
Cambriansedimentaryrocksareabsentthroughout
muchoftheprovincebutareexposedontheeastflankofthe
Rawlinsuplift(fig.1),wheretheyare450ftthick(Lovering,
1929).IntheCambrianFlatheadSandstone(fig.2),abasal
conglomeraticsandstoneisoverlainbyquartzosesandstone
orquartziteandbyreddish-brownglauconiticsandstoneand
shale.Theformationthinstotheeastandisentirelyabsent
atthewestendoftheLaramieBasinandintheShirley
Basin(Harshman,1972).RocksofOrdovician,Silurian,and
Devonianageareabsentintheprovince.
OntheRawlinsuplift,theMississippianMadison
LimestoneunconformablyoverliesCambrianstrata(fig.2).
Eastward,wheretheFlatheadisabsent,theMadisonrests
unconformablyonPrecambrianrocks.AlongtheRawlins
uplift,theMadisonisagraytoredlimestoneorcherty
limestone;akarstsurfaceiswelldevelopedintheupper
partoftheunit.TheMadisonaverages100ftthickonthe
Rawlinsuplift(Lovering,1929)and150ftthickinthe
ShirleyBasin(Harshman,1972),butitisthinorabsentin
theLaramieBasin.LillegravenandSnoke(1996)identified
98ftofMadisonLimestoneinthenorthernHannaBasin.
-
Geologic Assessment—Undiscovered Oil and Gas—Hanna, Laramie, and
Shirley Basins Province, Wyoming and Colorado 11
ANTICLINALSYNTECTONIC UPLIFTBASIN
PRECAMBRIA
N BASEMENT
SHALLOW OUT-OF-BASIN THRUST
ROCKS
BASEMENT-INVOLVED BLIND THRUST
Figure 5. Generalized cross section showing triangle zone
development as described by Lillegraven and others (2004) for
structures in the Hanna and Laramie Basins.
Wherepresent,thePennsylvanianAmsdenFormation
unconformablyoverliestheMadisonLimestone(fig.2).The
Amsden’ssandstone,reddishmudstone,andchertylimestone
(Lovering,1929)averages200ftthickontheRawlinsuplift.
Itthinsto140ftinthesouthernpartoftheHannaBasin.
Harshman(1972)didnotrecognizeAmsdenintheShirley
Basinbutidentifiedadistinctivesolutionbrecciaandkarst
zonewithreddishshaleandsandstonethatheplacedinthe
upperpartoftheMadison.HauselandJones(1984)didnot
recognizetheAmsdenFormationintheLaramieBasin,but
time-equivalentrocksoftheFountainFormationcropoutin
thesouthernpartofthebasinneartheWyoming-Colorado
stateline(fig.2).
ThePennsylvanianTensleepSandstoneunconformably
overliestheAmsdenFormationandaverages300–400ft
thickintheHannaBasin,whereitisdescribedasamediumgrained,crossbedded,quartzosesandstoneandlimestone
unit(Mitchell,1961;Stone,1966;figs.2,6).Theequivalent
CasperFormationaverages500ftthickintheLaramieBasin
andis650ftthickintheShirleyBasin,wheresomerocksin
thelowerpartarecorrelativewiththeAmsdenFormationto
thewest(Harshman,1972).TheCasperbecomesmorearkosic
southeastwardintheLaramieBasinandisinpartequivalent
totheFountainFormation.Fusiliniddataindicatethatlithic
unitsintheTensleep-Casperdepositionalsystemaretime
transgressive.IntheHannaBasin,theTensleepisprimarily
Desmoinesianinage,whereasthetopoftheCasperinthe
LaramieBasinisWolfcampian(Mitchell,1961).TheTensleep
isimportanttothepetroleumgeologyoftheprovincebecause
itisaregionalreservoirrock,particularlywheretheeolian
sandstonefaciesiswelldeveloped.
ThePermianandTriassicGooseEggFormation
unconformablyoverliestheTensleepSandstoneandCasper
Figure �. Tensleep Sandstone outcrop along west side of Seminoe
Reservoir (T. 24 N., R. 84 W.) in northern part of Hanna Basin.
Sandstones are fine-grained and cross-bedded sublitharenites
typical of the Tensleep in the region. Younger Jurassic rocks in
background. Hammer for scale in right center of photograph.
-
12 Undiscovered Oil and Gas–Hanna, Laramie, and Shirley Basins
Province, Wyoming and Colorado
Formation(fig.2).IntheHannaBasin,theGooseEgg
averages250ftthickandiscomposedofreddish-brown
calcareoussandstone,dolomiticlimestone,siltstone,and
anhydrite(fig.7).Itaverages400ftthickintheShirley
Basin.Namedmembersare,inascendingorder,theOpeche
Shale,MinnekahtaLimestone,GlendoShale,Forelle
Limestone,DifficultyShale,andErvayLimestoneMembers
(Harshman,1972;PiperandLink,2002).TheGooseEgg
istimeequivalenttothePhosphoriaFormationinwestern
Wyoming(CheneyandSheldon,1959)andrepresentsan
easternevaporitefaciesofthePhosphoriathatwasdeposited
intheGooseEggembayment(seefig.21)ofthePhosphoria
sea(PiperandLink,2002).TheGooseEggisimportant
tothepetroleumgeologyoftheprovincebecauseitforms
aregionalsealtotheeastwardmigrationofoilgenerated
fromPhosphoriasourcerocksinwesternWyomingand
southeasternIdaho(seelaterdiscussion).
FormationsintheTriassicChugwaterGroup(fig.2)
are,inascendingorder,theRedPeakFormation,Alcova
Limestone,andJelmFormation.IntheHannaandCarbon
Basins,theChugwaterGroupaverages1,300ftthickand
consistsofcoastalandshallowmarinelimestone,mudstone,
sandstone,andgypsum(Dobbinandothers,1929).The
Chugwaterischaracteristicallyredbutalsocontainsshades
ofgreen,purple,andbrown.Itisconformablewiththe
underlyingGooseEggFormationinthenorthernpartofthe
HannaBasin(LillegravenandSnoke,1996).TheAlcova
Limestoneisathin(10–15ftthick)discontinuousunitofhard,
sandylimestonethatlocallyformsridges.TheChugwateris
about1,100ftthickatRedMountainatthesouthendofthe
LaramieBasin(DartonandSiebenthal,1909)andisabout725
ftthickintheShirleyBasin(Harshman,1972).TheChugwater
isimportanttothepetroleumgeologyoftheprovincebecause
itformsaregionalsealforpetroleumtraps.Locally,Jelm
Formationsandstonesformreservoirsforoilandgasinthe
LaramieBasin(Mitchell,1961).
TheJurassicSundanceFormationunconformably
overliestheChugwaterGroupinmuchoftheprovince(fig.
2).TheunderlyingJurassicNuggetSandstone(notshownon
fig.2)hasbeenidentifiedinthewesternmostHannaBasin,
butitpinchesouttotheeastinthecentralHannaBasin
(Mitchell,1961).TheSundanceFormationconsistsofgray-
Figure �. Goose Egg Formation outcrop along west side of Seminoe
Reservoir (T. 24 N., R. 84 W.) in northern part of Hanna Basin. Red
mudrocks interbedded with tan evaporites. Note vertical faults in
central part of photograph. Field of view is approximately 30 ft
across.
-
Geologic Assessment—Undiscovered Oil and Gas—Hanna, Laramie, and
Shirley Basins Province, Wyoming and Colorado 1�
greenmarineshale,fossiliferouslimestone,andglauconitic
sandstone(Mitchell,1961;Harshman,1972).Dobbinandothers
(1929)measured350ftofSundancealongComoRidgeinthe
northernLaramieBasin(CBAoffig.3),about50percentof
whichissandstone.LillegravenandSnoke(1996)identified
morethan400ftofSundanceinthenorthernHannaBasin,and
Harshman(1972)reportedanaveragethicknessof240ftinthe
ShirleyBasin.TheSundanceFormationiscomposedofabasal
chert-pebbleconglomerateandsandstoneunit(“basalSundance”
offig.2)andatleasttwodistinctsandstoneunitsidentified
as“upperSundance”and“lowerSundance.”The“upper,”or
younger,sandstoneunitisareallyrestrictedtotheHannaand
LaramieBasins,whereasthe“lower,”orolder,sandstoneismore
widespread(Stone,1966).TheJurassicMorrisonFormation
conformablyoverliestheSundance.Sundancesandstone
reservoirsproducebothgasandoilintheLaramieBasin.
TheUpperJurassicMorrisonFormationrangesfrom
150to300ftthickintheprovinceandthickenssouthward
intoColorado.Itischaracterizedbygray,green,andmaroon
nonmarineshalesandmudstones,lithic-richsandstonesand
conglomeraticsandstones,andrarelimestones.Thelowerpart
oftheMorrisonisprimarilysandstone,andintheLaramie
Basinthisunitis140ftthick.IntheShirleyBasin,however,
thelowersandstoneoftheformationisonlyabout20ftthick
(Harshman,1972).Itisnotasignificantoilandgasreservoirin
theprovince.
TheLowerCretaceousCloverlyFormation
unconformablyoverliesJurassicrocksintheHanna,Laramie,
andShirleyBasinsProvince.ThenameCloverlyisusedfor
rocksequivalenttotheLowerCretaceousDakotaFormation,
FusonShale,andLakotaFormationoftheBlackHills;but
becauseeachoftheseunitsisnotcontinuousandconsistently
recognizableintheprovince,theyarecombined(fig.2;Stone,
1966).Bowen(1917)identifiedanaveragethicknessof231ft
fortheCloverlyFormationintheHannaBasin.AtOilSprings
field(fig.20)inthenorthernpartoftheLaramieBasin,the
Cloverlyincludesabasal10-ft-thicknonmarineunitofchertpebbleconglomerateandconglomeraticsandstone(fig.8),a
33-ft-thickmiddleunitofgraytogreencarbonaceousshale,
andanupper85-ft-thickunitofmarinesandstone(Dobbinand
others,1929).TheCloverlythinstothesouthandislessthan
100ftthickinthesouthernpartoftheLaramieBasin(Stone,
1966).Itisasmuchas200ftthickintheShirleyBasinwhere
thethickeningisdueprimarilytodevelopmentoftheupper
sandstoneunit(Harshman,1972).Bothsandstone-richunitsare
knownoilandgasreservoirsintheLaramieBasin.
Figure �. Basal Cloverly Formation conglomerate along west side
of Seminoe reservoir (T. 24 N., R. 84 W.) in northern part of Hanna
Basin. Clasts are dominantly quartzite and chert. Maximum clast
diameter approximately 8 in. Hammer for scale in left center of
photograph.
-
1� Undiscovered Oil and Gas–Hanna, Laramie, and Shirley Basins
Province, Wyoming and Colorado
TheLowerCretaceousThermopolisShaleispresent
throughouttheprovince(figs.2,9).Itrangesinthicknessfrom
200ftinthenorthernLaramieandHannaBasins(Dobbin
andothers,1929)to185ftintheShirleyBasin(Harshman,
1972)andto50ftinthesouthernLaramieBasin(Mitchell,
1966).Itisprimarilydark-graymarineshalewithavariably
developedsandstoneunitcalledtheMuddySandstone
Memberinthemiddle(Eicher,1960).Thelowershaleunit,
commonlyreferredtoastheSkullCreekShale(Burtner
andWarner,1984),isAlbianinageandisassociatedwith
theinitialCretaceousmarinetransgression.TheMuddy
SandstoneMemberisacompositeunitofforeshoreto
shorefaceregressivesandstonesthatareincisedinplaces
byfine-tocoarse-grainedvalley-filldepositsofsandstone
andshalethatare,inturn,overlainbytransgressivemarine
sandstones(Dolsonandothers,1991).Owingtoitslithologic
heterogeneity,theMuddyisanimportantpetroleumreservoir
insomepartsoftheprovincebutisapoorreservoirormay
evenbeabsentinotherparts(Stone,1966).Theupperpartof
theThermopoliscontainsanunnameddark-grayshalethat
isequivalenttotheinformallynamed“ShellCreekshale”
memberoftheThermopolisShaleinnorthernandeastern
WyomingandcentralMontana(Eicher,1962;Dymanand
others,1994;PorterandWilde,2001).
TheMowryShale(figs.2,10)isasequenceofdark-gray
toblacksiliceousmarineshalewithinterbeddedporcellanite
andbentonite.IntheHannaandLaramieBasins,itrangesin
thicknessfrommorethan200ftinthenorthto150ftinthe
south(Dobbinandothers,1929).Mitchell(1961)identified
400ftofMowryintheLaramieBasin,buthemayhave
includedtheinformal“ShellCreekshale”unit.Harshman
(1972)recognizedanaverageMowrythicknessof110ftinthe
ShirleyBasin.ThetopoftheMowryisidentifiedbyaregional
bentonitebedofCenomanianage,theClaySpurBentonite
Bed(BurtnerandWarner,1984;Davisandothers,1989;
Obradovich,1993).ByersandLarson(1979),Burtnerand
Warner(1984),Davisandothers(1986),andDavisandByers
(1989)identifiedregionallithofacieswithintheMowryand
designateditamajorsourcerockforpetroleuminthenorthern
RockyMountainregion.WediscusstheMowry-Hanna
CompositeTPSinalatersectionofthisreport.
TheFrontierFormation(figs.2,11)consistsofalower
unitofdark-graycarbonaceousshale,theBelleFourcheShale
Member,andanupperunitofsandstoneandinterbedded
shale,theWallCreekSandstoneMember.Theformation
averagesabout700–900ftthickintheprovince(Stone,1966;
Harshman,1972;Mieras,1992;LillegravenandSnoke,
1996);itisLateCretaceous(Cenomanian-Turonian)inage.
TheBelleFourcherepresentsregressivemarinedeposition
andcontainslesssandstoneeastwardintheLaramieBasin.
TransgressivemarinesandstonesoftheWallCreekSandstone
Memberaverage10–40ftthick(fig.11)andarefine-grained
andglauconitic.Theunitis110ftthickintheShirley
Basin(Harshman,1972).WallCreeksandstones,whichare
petroleumreservoirsintheprovince,arediscussedinalater
sectionofthisreport.
IntheHannaBasin,rocksimmediatelyabovetheFrontier
arecalledtheSageBreaksShale(fig.2;Merewether,1990)or
NiobraraFormation(LillegravenandSnoke,1996).Dobbin
andothers(1929)identified450ftofdark-grayconcretionary
shaleasequivalenttotheSageBreaksMemberoftheCarlile
ShaleoftheBlackHills.Mitchell(1961)identifiedabout
1,200ftofNiobrara(includingtheSageBreaksShale)in
theHannaBasinandabout600ftinthesouthernLaramie
Basin.TheSageBreaksShalecontainsammonitesofLate
Cretaceous(Turonian)age(Stone,1966).Niobrararocks
abovetheSageBreaksShalearecalcareousshales,limestones,
andchalkylimestones(fig.12).TheNiobraraisconcretionary
andcontainsledge-formingcoquinabeds.Harshman(1972)
measuredabout900ftofNiobrara(includingtheSageBreaks
Shale)intheShirleyBasin.Limestonesandchalksinthe
Niobraragiveoffastrongpetroliferousodorandformthe
NiobraraTPSdiscussedlaterinthisreport.
TheSteeleShaleconformablyoverliestheNiobrara
Formation(figs.2,13).Itisdark-graymarineshaleand
minorinterbeddedsandstone,siltstone,andbentoniteof
earlyCampanianage.Apersistent5-ft-thickbentoniteinthe
upperpartoftheSteeleinthenorthwesternLaramieBasinis
equivalenttotheArdmoreBentoniteBedoftheBlackHills
region(Gillandothers,1970;Obradovich,1993).TheSteele
rangesinthicknessfrom3,500ftinthenorthernHannaand
LaramieBasinsto2,400ftinthewesternHannaBasinand
to2,300ftinthesouthernLaramieBasin(Gillandothers,
1970).LillegravenandSnoke(1996)recognized5,500ftof
SteelestratainthenorthernHannaBasin.Thindiscontinuous
sandstones,referredtoinformallyas“Shannon”sandstones,
aregasreservoirsintheHannaandLaramieBasins.The
Steelecontainslocallycontinuoussandstonesatornearthe
topthatareequivalenttobasalsandstonesoftheMesaverde
Groupfartherwest.IntheShirleyBasin,Harshman(1972)
estimatedtheSteeletobe1,500–2,000ftthick,butthereit
hasbeenpartlyerodedandallyoungerCretaceousstratahave
beenentirelyremovedbyerosion.TheSteeleShaleispart
oftheMowry-HannaCompositeTPSdiscussedlaterinthis report.
TheoverlyingMesaverdeGroupisconformablewith
boththeSteeleShaleandtheoverlyingLewisShaleinthe
Hanna,Laramie,andShirleyBasinsProvince.Itisdivided
intofourformationsintheHannaBasin—inascendingorder,
theHaystackMountainsFormation,AllenRidgeFormation,
PineRidgeSandstone,andAlmondFormation(fig.2;Gilland
others,1970).IntheLaramieBasin,theMesaverdeconsistsof
theRockRiverFormationandoverlyingPineRidgeSandstone
owingtoaneastwardfacieschangefromsandstonetoshale.
TheRockRiverFormationislargelythetimeequivalent
oftheAllenRidgeFormation.TheHaystackMountains
Formationconsistsof1,700–2,550ftofinterbeddedmarine
sandstoneandshale(fig.14).ThelithologicallydiverseAllen
RidgeFormationcontainsaunitofnonmarinesandstoneand
carbonaceousshale700–1,200ftthickwhich,intheeastern
HannaBasin,isunderlainandoverlainlocallyby350–700
ftofmarinetobrackish-watersandstoneandshale(Gilland
-
Geologic Assessment—Undiscovered Oil and Gas—Hanna, Laramie, and
Shirley Basins Province, Wyoming and Colorado 15
Figure �. Muddy Sandstone Member of Thermopolis Shale and the
Cloverly Formation; view looking southwest near Rendle Hill,
approximately 15 mi north of Rawlins, Wyo. (T. 24 N., R. 88 W.), in
western part of Hanna Basin. Muddy Sandstone Member in lower left,
Thermopolis Shale in dark gray middle area, and Cloverly Formation
in light gray background forming dip slope. Foreground distance
approximately 20 ft across
Figure 10. Mowry Shale near Rendle Hill, approximately 15 mi
north of Rawlins, Wyo. (T. 24 N., R. 88 W.), in western part of
Hanna Basin. Hammer for scale near center of photograph.
-
1� Undiscovered Oil and Gas–Hanna, Laramie, and Shirley Basins
Province, Wyoming and Colorado
Figure 11. Frontier Formation along Union Pacific Railroad
tracks near Como, Wyo. (T. 22 N., R. 78 W.), in central part of
Hanna Basin. Upper part of outcrop is sandstone of Wall Creek
Sandstone Member. Foreground distance approximately 150 ft
across.
Figure 12. Niobrara Formation at Separation Flats, approximately
8 mi northeast of Rawlins, Wyo. (T. 22 N., R. 86 W.), in western
part of Hanna Basin. Younger rocks are to left. Foreground distance
approximately 30 ft across. Steele Shale and Mesaverde Group form
gray hills on horizon at far left.
-
Geologic Assessment—Undiscovered Oil and Gas—Hanna, Laramie, and
Shirley Basins Province, Wyoming and Colorado 1�
Figure 1�. Steele Shale at Separation Flats, approximately 10 mi
northeast of Rawlins, Wyo. (T. 22 N., R. 86 W.), in western part of
Hanna Basin. Looking upsection at concretionary zones that form
“knobby” ridges in middle part of Steele, top center of photograph.
Foreground distance approximately 10 ft across.
others,1970).ThePineRidgeSandstoneunconformably
overliestheAllenRidge.Martinsenandothers(1993)
suggestedthatthisunconformityseparatesdifferentsequences
derivedfromdifferentdirectionsandwasrelatedtoearly
LaramideupliftnorthoftheHannaBasin.IntheHanna
Basin,theformationisa100–250-ft-thickunitofnonmarine
sandstone,siltstone,carbonaceousshale,andimpurecoal(fig.
15).TheAlmondFormationisamarineandnonmarinecoastal
sequenceofsandstone,shale,andcoalranginginthickness
from450to600ft.InthewesternHannaBasin,fluvial
sandstone,shale,andcoalinthenonmarinelowerpartofthe
Almondareabout180ftthick.Itcontainsasmanyasseven
coalbedsgreaterthan5ftthick.TheMesaverdeGroupisboth
asourceandreservoirrockintheprovinceandisdiscussed
aspartofcoalbedgasandcontinuousgastotalpetroleum
systemslaterinthisreport.
TheMaastrichtianLewisShale(fig.2)wasdeposited
duringthefinaltransgressive-regressivephaseoftheWestern
InteriorseawayandduringtheearlypartoftheLaramide
orogeny(Perman,1990).Itisathick(2,200–2,600ft)
sequenceofgraymarineshale,fine-tomedium-grained
sandstone,andsiltstone.InthewesternpartoftheHanna
Basin,itformscoarsening-upwardparasequencesofshale
andsandstonethatareasmuchasafewhundredfeetthick
(fig.16).The600-ft-thickDadSandstoneMemberofthe
Lewisseparatesloweranduppershale-richintervalsofthe
Lewis.Numeroussandstonebodiesintheupperpartofthe
formationintheeasternpartoftheSouthwesternWyoming
ProvincetothewestandinthewesternHannaBasinare
laterallyequivalenttotheFoxHillsSandstone,andthat
nameisusedinsomeplaces(Gillandothers,1970;Fox,
1971).SandstonesandshalesoftheLewiscontainmarine
megafaunaofMaastrichtianagefromBaculites eliasithrough B.
clinolobatus(Gillandothers,1970).TheLewisisaknown
sourceandreservoirrockintheregion.Itispartofthe
Mowry-HannaCompositeTPSdiscussedlaterinthisreport.
TheMedicineBow,Ferris,andHannaFormationsare
syntectonicsedimentaryunitsassociatedwiththeLaramide
orogeny.TheyareprimarilyrestrictedtotheHannaBasinand
northernpartoftheLaramieBasinwheretheyrecordahistory
ofperiodicupliftofsurroundingLaramidestructures,sea
levelfluctuations,andsubsidence(Knight,1951;W.R.Keefer,
writtencommun.,1999;Wroblewski,2003).Theseformations
areimportanttoourstudybecausetheycontainnumerouscoal
bedsandlacustrinemudstonesthatarehydrocarbonsources.
InthedeeperpartsoftheHannaBasin,fluvialsandstone
reservoirsmaycontaingasaccumulations.
TheMedicineBowFormation(fig.2)wasdeposited
duringthefinalwithdrawaloftheMaastrichtianseafromthe
Hanna,Laramie,andShirleyBasinsProvinceduringearly
stagesoftheLaramideorogeny.Itisathick(about6,200
ft)nonmarinesequenceoffluvialtoestuarinesandstone,
carbonaceousshale,andcoal(fig.17;LandonandHeller,
2000).High-volatileAorBbituminouscoalsareespecially
abundantinthelowerpartoftheformation,andintheHanna
coalfieldinthecentralHannaBasinasmanyas30individual
coalbedshavebeenidentified(fig.1).However,onlythreeof
thesecoalbedsexceed5ftinthickness(GlassandRoberts,
1980).TheMedicineBowFormationisconformablyoverlain
bytheFerrisFormation(figs.2,18)orislocallyinangular
discordancewiththeHannaFormationintheeasternHanna
andLaramieBasins(Gillandothers,1970).
TheUpperCretaceoustolowerPaleoceneFerris
Formationismorethan6,000ftthickatitstypelocalityinthe
HannaBasin,whereitisentirelynonmarine.Itcanbedivided
intotwolithicunits:alower1,100-ft-thickUpperCretaceous
unitcomposedofconglomeraticsandstone,sandstone,and
shaleandanupper5,400-ft-thickPaleoceneunitofsandstone
andcoal(Gillandothers,1970).GlassandRoberts(1980)
identified28coalbedsinthecentralHannaBasinrangingin
thicknessfrom4.5to25ft.
ThePaleoceneandEoceneHannaFormationmaybeas
thickas13,000ftinthenorthernpartoftheHannaBasin,but
itisgenerallymuchthinner.Itisafluvial-lacustrinecyclic
sequenceofconglomerate,sandstone,mudstone,shale,and
coal(figs.2,19).Depositionalcyclesaredefinedbythe
-
1� Undiscovered Oil and Gas–Hanna, Laramie, and Shirley Basins
Province, Wyoming and Colorado
Figure 1�. Haystack Mountains Formation along North Platte
River, approximately 10 mi north of Sinclair, Wyo. (T. 22 N., R. 85
W.), in western part of Hanna Basin, showing coarsening-upward
parasequences in upper part of formation. Approximately 700 ft of
formation exposed.
Figure 15. Pine Ridge Sandstone along North Platte River,
approximately 10 mi north of Sinclair, Wyo. (T. 22 N., R. 85 W.),
in western part of Hanna Basin, showing sandstone, mudstone, and
coal interbedded in middle part of formation. Coal bed in middle
part of photograph approximately 18 in. thick.
-
Geologic Assessment—Undiscovered Oil and Gas—Hanna, Laramie, and
Shirley Basins Province, Wyoming and Colorado 1�
Figure 1�. Lewis Shale, approximately 12 mi north of Sinclair,
Wyo. (T. 22 N., R. 85 W.), in western part of Hanna Basin, showing
coarsening-upward parasequence of shale and sandstone in lower part
of formation. Person for scale at left center.
Figure 1�. Sandstone bed in the Medicine Bow Formation on Snyder
Ridge (T. 24 N., R. 83 W.) in northern part of Hanna Basin. Staff
in left center portion of photograph is 5 ft tall.
-
20 Undiscovered Oil and Gas–Hanna, Laramie, and Shirley Basins
Province, Wyoming and Colorado
Figure 1�. Ferris Formation, approximately 3 mi west of Hanna,
Wyo. (T. 22 N., R. 82 W.), along U.S. Highways 30 and 287 in
central part of Hanna Basin, showing interbedded carbonaceous
shale, coal, and sandstone. Middle-ground distance approximately
125 ft across.
sedimentaryresponsetoupliftandsubsidenceduringthe
mainphaseoftheLaramideorogeny.TheHannacontains
morethan30individualcoalbedsatleast5ftthickofhighvolatileCbituminousrankthataredistributedthroughout
theformation(GlassandRoberts,1980).Theformation
unconformablyoverliestheFerrisFormationinthecentral
HannaBasin,butitrestsonolderrocksalongthenortheast
marginofthebasin(Gillandothers,1970).
UpperEoceneandyoungerrocksarelimitedmainly
totheShirleyBasin.TheEoceneWindRiverFormation,
theoldestunit,consistsofabasalconglomerateandarkosic
sandstoneoverlainbyinterbeddedcoarse-tomedium-grained
sandstone,siltstone,claystone,andminorlignitebeds;
maximumthicknessisabout500ft(Harshman,1972).The
WindRiverunconformablyoverliestheSteeleShaleinthe
ShirleyBasin.TheWagonBedFormationisalsoEocenein
ageandconformablyoverliestheWindRiverFormation(fig.
2).Itiscomposedofinterbeddedcoarse-grainedsandstone
andclaystonethatreachamaximumthicknessofabout150
ft(Harshman,1972).
TheOligoceneWhiteRiverFormationunconformably
overliestheWagonBedorolderrocksintheShirleyBasin.
Inmanyplacesitconsistsofabasalconglomerate,overlain
bytuffaceoussiltstone,sandstone,andlimestonebedsand
localinterbeddedconglomerates.TheWhiteRiverhas
beendividedintoalowermemberthatisasmuchas400ft
thickandanuppermemberthatisasmuchas350ftthick (Harshman,1972).
TheMioceneArikareeFormationconformablyoverlies
theWhiteRiverFormationintheShirleyBasin.Itconsistsof
fine-tomedium-grainedtuffaceoussandstone,conglomerate,
andlimestonewithamaximumthicknessofabout180ft
(Harshman,1972).IntheHannaBasinMiocenerocksare
locallypresent.TheyunconformablyoverlietheHanna
FormationandareassignedtotheBrownsParkFormation
(Blackstone,1993).NoneoftheTertiaryformationsyounger
thantheHannaisthoughttohavehydrocarbonpotential.
Production Characteristics
Twelvesignificantfields(cumulativeproductiongreater
than0.5millionbarrelsofoilequivalent)havebeendiscovered
intheHanna,Laramie,andShirleyBasinsProvince;allare
locatedalongthewestmarginoftheLaramieBasin(fig.20),
wheretheyproducefrom7differentreservoirs.Table3shows
theassessmentunitnumberandname,primaryreservoirs,
fieldname,discoveryyear,meandepthofproducinginterval,
commodity,andcumulativeproductionforthesefields,as
compiledfromHollisandPotter(1984)andIHSEnergy
Group(2004a).The12fieldsarefoundin2TPSsthatare
discussedinthefollowingsectionsofthisreport.Asshown
intable3,productionfromthesefieldshasbeenmorethan
77millionbarrelsofoil(MMBO)and24billioncubicfeetof
gas(BCFG)fromatotalofabout79MMBOand31.8BCFG
-
Geologic Assessment—Undiscovered Oil and Gas—Hanna, Laramie, and
Shirley Basins Province, Wyoming and Colorado 21
Figure 1�. Hanna Formation, approximately 2 mi west of Hanna,
Wyo. (T. 22 N., R. 82 W.), in a road cut along U.S. Highways 30 and
287 in central part of Hanna Basin, showing interbedded
carbonaceous shale, coal, and sandstone. Person (E.A. Merewether)
for scale.
fromallfieldsintheprovince.Nearly65percentofthatoil
hasbeenproducedfromJurassicandCretaceousreservoirsat
RockRiverfieldinthenorthwesternpartoftheLaramieBasin
(fig.20).Threefields(RockRiver,Quealy,andBigMedicine
Bow)accountformorethan85percentoftheoilproduced
intheprovince.Only2ofthe12fieldshaveappreciablegas
reservoirs(BigMedicineBowandRockRiver);theirtotal
cumulativeproductionis22.6BCFG(table3).Allotherfields
produceconsiderablylessgas.
TheHannaBasinhostsonlythreefields,noneofwhichis
significant.HugusandOverlandarebothNiobraraoilfields,
andCedarRidgehasproducedgasfrom“Shannon”sandstones
(straysandstonesintheSteeleShale).Inaddition,twocoalbed
gaspilotprojectsareunderwayinthenorthernpartofthe
HannaBasin—theSeminoeRoadPilotProject(Mesaverde
Groupcoals)andtheHannaDrawPilotProject(Hanna
Formationcoals)(Debruin,2003b;fig.20).Cretaceousrocks
intheHannaBasincenterhaveonlyrecentlybeenpenetrated
butarenotyeteconomicallyproductive(DeBruin,2003a,b).
Severaldeepwellshavebeendrilledinthecentralpartofthe
HannaBasinandarediscussedinaseparatesection.
Productionisprimarilyfromstructuraltraps,butthere
isapotentialfortrapsformedbyfaciesvariations.Structural
trapsmaybethrust-faultedanticlines,trianglezones,and
combination(structural-stratigraphic)trapsinwhichfacies
variationscontrolthesandstonedistributionacrossstructures.
Insomestructures,trappingmechanismsarecomplexowing
toremigrationofoilfromlatePaleozoic(AncestralRocky
Mountains)trapstoLaramidetraps;forexample,atQuealy
fieldPhosphoria-derivedTensleep-Casperoilaccumulatedin
thismanner(Stone,1995).
Fiveofthe12significantfields,theAllenLakeEast,Big
MedicineBow,Herrick,LittleLaramie,andQuealyfields
inthewesternLaramieBasin,produceoilfromreservoirsin
theTensleepSandstoneandCasperFormation.Thesefields,
whichwerediscoveredinthelate1940sto1950,haveatotal
cumulativeproductionof8.5MMBO(table3).
TheexplorationhistoryoftheHanna,Laramie,and
ShirleyBasinsProvincecanbedividedintoearly,middle,
andlatestages.Duringtheearlystage,from1918totheearly
1940s,fielddiscoverieswerebasedprimarilyonsurface
mappingofstructuressuchasatRockRiverandRexLake
(Stone,2002).Duringthemiddlephase,inthe1950s,fields
werediscoveredusingseismicexplorationmethods,suchas
atDiamondLakeandElkMountain.Cretaceousreservoirsat
QuealywerethefirstseismicdiscoveryintheRockyMountain
region,in1934(table3).Thelateststageofexploration
(sincethe1970s)hasbeendominatedbydeepdrillingusing
improvedtechnology,butnosignificantfieldshavebeen discovered.
Thelackofdiscoveredoilorgasaccumulationsinthe
ShirleyBasinisenigmatic.Theareahasbeenmoderately
explored,andsome80wells(alldryandabandoned)were
drilled,mostofwhichwerelocatedinthreeareas(fig.1):(1)
eastofthe+2000ftcontouronPrecambrianbasementonthe
eastsideofthebasin,(2)ontheanticlineinthenorthwestern
partofthebasin,and(3)withinthefaultedShirleyMountains
areainthesouthwesternpartofthebasin(fig.3).Manyof
thesewellspenetratedPaleozoicstrata,andsomereached
Precambrianbasement.Therehavebeenabout40drillstemtestsinformationsrangingfromtheMuddySandstone
MemberoftheThermopolisShaletotheTensleepSandstone
(fig.2),butnonereportedshowsofoilorgas(IHSEnergy
Group,2004b).ThislackofhydrocarbonsintheShirleyBasin
isdifficulttoexplain,becausePhosphoriaoilshouldhave
beenabletomigrateintotheShirleyBasinfromthewestin
amannersimilartothatelsewhereintheprovince(seethe
discussionofthePhosphoriaTPSlaterinthisreport).Barriers
couldpossiblyhaveformedbetweenthisbasinandtheHanna
andLaramieBasinstopreventsuchmigration,butdirect
evidenceislackingandthequestionremainsunresolved.
-
22
!(
!(
!(
#0 Hanna
Rawlins
0
-4000
-5000
-2000
-10000
-1000
+2000
-20000
+5000
+4000
+6000
-25000
+8000
-30000
0 0
+600
0
0
+200
0
-200
0
+5000
-500
0
+4000
+400
0
-1000
0
+500
0
+4000
-2000
+5000
+2000
+2000
+2000
0
+5000
+400
0
+400
0
-5000
0 +2000
+2000
0
+2000
+4000
-10000
+5000
-1000
+2000
+5000
0
+400
0
Rock River
Quealy
Dutton Creek
Rex Lake Big Hollow
Simpson Ridge Big Medicine Bow
Oil Springs
Cooper Cove
Seven Mile
Diamond Ranch
Chapman Draw
Elk Mountain
Allen Lake East
Little Medicine Bow
Allen Lake
Big Medicine Bow South
Poverty Ditch
Overland
Hugus
Hanna Draw
Seminoe Road
PC
BR
BU
17-2
!( Horseshoe Ridge
107° 106°30' 106°
41°30'
42°
0 5 102.5 MILES
L a r a m i e B a s i n
H a n n a B a s i n
R a w l i n s U p l i f t
S i e r r a M a d r e
M e d i c i n e B o w M o u n t a i n s Ch
eyenn
e belt
Southwestern part of the Hanna, Laramie, and Shirley Basins
Province showing locations of oil (green), gas (red), and oil and
gas (yellow) fields, wells used to model thermal history of the
southern part of province (green filled circles), locations of the
Hanna Draw and Seminoe Road coalbed gas pilot projects (red
tracts), and Anadarko Durante 17-2 well (green triangle). Contours
drawn on top of Precambrian basement in feet relative to sea level
(modified from Blackstone, 1989). Heavy gray lines are major
faults. Red patterned areas are outcrops of Precambrian rocks from
Green (1992) and Green and Drouillard (1994). Location of Cheyenne
belt from Stone (1995). BR, Brinkerhoff Hanna Unit No. 1 well; BU,
Buttes Federal 1–18 well. PC, Humble Pass Creek Ridge No. 1
well.
Figure 20.
Undiscovered O
il and Gas–H
anna, Laramie, and Shirley B
asins Province, Wyom
ing and Colorado
-
Geologic Assessment—Undiscovered Oil and Gas—Hanna, Laramie, and
Shirley Basins Province, Wyoming and Colorado 2�
Assessment of Oil and Gas Resources
System for Numbering Assessed Resources
IntheHanna,Laramie,andShirleyBasinsProvince
weassessedthe5TPSsand7AUslistedbelow.Theyare
numberedaccordingtoasystemestablishedbytheUSGS
tofacilitatepetroleumresourceassessment(U.S.Geological
Survey,2000):thefirstdigit(5)referstotheregion,thenext
three(030)totheprovince,thenexttwo(01,02,andsoon)to
theTPS,andthelasttwodigitstotheassessmentunit.
503001 PhosphoriaTPS
50300101 Tensleep-Casper ConventionalOil
andGasAU
503002
Mowry-HannaComposite TPS
50300201
Mesozoic-Cenozoic ConventionalOil andGasAU
BiogenicGas,MedicineBow–Ferris–HannaCoalbedGas,and
MesaverdeCoalbedGasAUswerenotassessedowingtoa
lackofgeologicdataandinadequateproductiondata.]
Athoroughanalysisofallavailablegeologicdata,as
wellaspetroleumexplorationanddevelopmentinformation,
waspresentedtoareviewpanelforafinaldetermination
ofthecriteriaandboundariestobeusedforeachAU.In
addition,estimatesofthesizesandnumbersofundiscovered
conventionaloilandgasaccumulations,basedonatabulation
ofexistingfieldandwellrecordsprovidedbyKlettandLe
(2007)(thisCD-ROM),werepresentedondatainputforms
tothereviewpanel.Theseinput-dataforms(seeKlettand
Le,2007,thisCD-ROM)constitutethebasisforestimating
hydrocarbonresourcesintheAUs.
Thedefaultminimumaccumulationsizethathaspotential
foradditionstoreservesforconventionalaccumulationsis
0.5millionbarrelsofoilequivalent(MMBOE).TheNiobrara
ContinuousOilAUwasassessedusingthemethodology
describedbySchmoker(1996),whereinthenumberof
untestedcellswithpotentialforadditionstoreservesandtotal
recoverypercellwereestimated.ForthatAU,theminimum
recoveryis1,000barrelsofoilpercell.Otherdatawere
compiledorcalculatedforeachAUtoaidinthefinalestimate
ofundiscoveredresources:gas-oilratio,naturalgasliquids
togasratio,APIgravity,sulfurcontent,anddrillingdepth.
Additionally,allocationsofundiscoveredresourceswere
calculatedforFederal,State,andprivatelandsandforvarious
ecosystemregions.Dataareavailableonthecompleteddata
inputformsforthethreeassessedAUsinKlettandLe(2007)
(thisCD-ROM).
The“wells”shownontheAUmapsinthisreportare
generalizedlocationsofwellscalled“cells.”Cellmapsfor
eachoilandgasassessmentunitwerecreatedbytheUSGS
toillustratethedegreeofexploration,typeofproduction,and
distributionofproductioninanAUorprovince.Eachcell
representsaquarter-milesquareofthelandsurface,andthe
cellsarecodedtorepresentwhetherthewellslocatedwithin
thecellarepredominantlyoil-producing,gas-producing,
bothoil-andgas-producing,dry,orofunknownproduction
type.Thewellinformationwasinitiallyretrievedfromthe
IHSEnergyGroup,PI/DwightsPLUSWellDataonCDROM(IHSEnergyGroup,2004b).Cellsweredevelopedas
agraphicsolutiontoovercometheproblemofdisplaying
proprietaryPI/DwightsPLUSWellData.Consequently,
proprietarydataarenotdisplayedonorusedinthecellmaps.
Forthisstudy,wedefineddryholesforeachAUaswells
thatreachedtotaldepthinorthroughtheassessedformations
andmoreoverwereclassifiedasdryandabandonedinthewell
databaseforformationsinthatAU.Dryholesaredistributed
relativelyevenlyintheLaramieBasinbuthavenotpenetrated
50300261 HannaBasinContinuousGasAU
(notquantitativelyassessed)
503003 NiobraraTPS
50300361 NiobraraContinuousOilAU
503004 NiobraraBiogenicGasTPS
50300461 NiobraraBiogenicGasAU (notquantitativelyassessed)
503005 Hanna-MesaverdeCoalbed GasTPS
50300581 MedicineBow–Ferris–Hanna CoalbedGasAU
(notquantitativelyassessed)
50300582 MesaverdeCoalbedGasAU (notquantitativelyassessed)
EachAUwasdefinedonthebasisofgeologic
characteristicsandconditionsfavorableforhydrocarbon
generationandaccumulation—suchassource,reservoir,
andsealrocks;burial,thermal,andmigrationhistories;and
trappingmechanisms—thatcombinetodistinguishitfrom
otherAUs.[Note:HannaBasinContinuousGas,Niobrara
-
2� Undiscovered Oil and Gas–Hanna, Laramie, and Shirley Basins
Province, Wyoming and Colorado
thedeepestpartoftheHannaBasin.Thefollowingsections
describethecharacteristicsoftheTPSsandthequantitatively
assessedAUswithintherespectiveTPSs.
Links to Data Input Forms and Graphical Data
KlettandLe(2007)(thisCD-ROM)providefilesofinput
formsandgraphicaldatathatwereusedintheassessmentof
theHanna,Laramie,andShirleyBasinsProvince.Twosetsof
exploration-activityanddiscovery-historygraphsareprovided
foreachoftheAUs,onesetshowingknownfieldsizes
(cumulativeproductionplusremainingreserves)andanother
setshowingfieldsizesthatwereadjustedtocompensate
forpotentialreservegrowthinthenext30years(labeled
“grown”).Withineachsetofgraphs,oilfieldsandgasfields
areshownseparately.Thelinks,below,directlyaccessthe
materialinKlettandLe’schapterofthisreport.
Data Input Forms:
Tensleep-CasperConventionalOilandGasAU (50300101)
Mesozoic-CenozoicConventionalOilandGasAU (50300201)
NiobraraContinuousOilAU(50300361)
Graphs of Exploration and Discovery Data for Conventional
Assessment Units
Tensleep-CasperConventionalOilandGasAU (knownfieldsizes)
Tensleep-CasperConventionalOilandGasAU (grownfieldsizes)
Mesozoic-CenozoicConventionalOilandGasAU
(knownfieldsizes) Mesozoic-CenozoicConventionalOilandGasAU
(grownfieldsizes)
Phosphoria Total Petroleum System
Thegeographicextentsofbothsourceandreservoirrocks
thatconstitutethePhosphoriaTPSareshowninfigure21.
TheTPSextendseastwardandincorporatesvirtuallyallof
theHanna,Laramie,andShirleyBasinsProvince,butbecause
Phosphoriasourcerocksdonotextendintotheprovince,the
conceptoflong-distancemigrationofoilisimportanttoour
understandingofthisTPS.
KeyelementsofthePhosphoriaTPS:
•
Sourcerocksofappropriateorganiccontentandsufficientthermalmaturitytogeneratehydrocarbons,
suchastheMeadePeakandRetortPhosphaticShale
MembersofthePhosphoriaFormation.
• Long-distancemigrationpathways,suchasvertical
pathsthroughfaultsandfractures,andlateral(updip)
pathsalongbeddingplanesanddisconformities.
•
Reservoirrocks,inthiscasethesandstonesofthePennsylvanianTensleepSandstoneandCasperFormation.
•
Traps,suchasthrust-faultedanticlines,complextrianglezones,sedimentarypinchouts,andcombinationsof
thesefeatures,alongwithenclosingshale,mudstone,
andevaporiteunitsandothertightlycementedbeds thatactasseals.
Figure22isatotalpetroleumsystemeventschartfor
thePhosphoriaTPSandtheTensleep-CasperConventional
OilandGasAU.Thischartsummarizestherelativeagesof
sourceandreservoirrocks;seals;overburden;trapformation;
generation,migration,andaccumulationofoilandgas;and
thecriticalmoment(timeofmaximumburialdepth),as
discussedindetailbelow.
Source Rocks
Lillisandothers(2003)identifiedseveraloiltypesin
Paleozoic,Cretaceous,andTertiarystrataintheUintaand
PiceanceBasinsofnortheasternUtahandnorthwestern
Coloradoonthebasisofgeochemicalcompositionof
sampledoil.TheirPhosphoriaoiltypeiswidelydistributed
inPennsylvanianthroughJurassicreservoirsintheUinta-PiceanceandSouthwesternWyomingProvinces.Johnson
(2003)recognizedPhosphoriaoilinthePennsylvanian-PermianWeberSandstoneatRangelyfieldinnorthwestern
Colorado;thatreportalsoidentifies65oilandgasfieldsinthe
SouthwesternWyomingProvincethatproducePhosphoriaoil
from18pre-CretaceousreservoirsintheTPS.
Regionally,thePhosphoriaoiltypeischaracterizedby
highsulfurcontent(0.5–1.4wtpercentsulfur)andpristanephytanevaluesoflessthan1.0(Lillisandothers,2003).For
thecurrentassessment,sampleswereanalyzedfromCasper
FormationreservoirsatHerrick,LittleLaramie,AllenLake
East,andQuealyfieldsintheLaramieBasin.Sulfurvaluesfor
thesefieldsrangedfrom2.5to3.5wtpercent(fig.23).Two
TensleepoilsampleshavingmoderatetohighAPIgravity
andlowsulfurareatO’BrienSpringsandBigMedicineBow
fields(fig.23).Theregionaldifferenceinweightpercent
sulfurmaybeduetovariationsinPhosphoriasourcerock
faciesandkerogencomposition,themixingofoilsfromother
sourcerockswiththePhosphoria,ordifferencesinthermal
history(PaulLillis,USGS,oralcommun.,2005).Lowsulfur
oilsinJurassicSundanceFormationreservoirs(fig.23)in
theLaramieBasinatElkMountain,RockRiver,Quealy,and
LittleMedicineBowfieldsareinterpretedasderivedfrom
MowryoilsoftheMowry-HannaCompositeTPSratherthan
fromPhosphoriaoils.
-
Geologic Assessment—Undiscovered Oil and Gas—Hanna, Laramie, and
Shirley Basins Province, Wyoming and Colorado 25
"
"
(( (((( ((
((
((((( ( (((((((((((((
(((((
((((
(
THRUST BELT
(
(((
W y o m i n g
U t a h
M o n t a n a
C o l o r a d o
I d a h o
C a s p e r
L a r a m i e
1 1 1 ° 1 0 8 ° 1 0 5 °
3 9 °
4 2 °
4 5 °
0 5 0 1 0 02 5 MILES
Sublett Basin (Phosphoria Formation depocenter)
Goo
seEg
g em
baym
ent
Q u a d r a n t S a n d s t o n e
T e n s l e e p S a n d s t o n e
C a s p e r F o r m a t i o n
F o u n t a i n F o r m a t i o n
P r o v i n c e b o u n d a r y
W e b e r S a n d s t o n e
Limit of reservoir rocks
T e n s l e e p S a n d s t o n e
Figure 21. Pennsylvanian and Permian source and reservoir rocks
in western Wyoming and adjacent areas and the Phosphoria Total
Petroleum System in the Hanna, Laramie, and Shirley Basins Province
(outlined in red), showing the distribution of Phosphoria source
rocks (Sublett Basin, within blue crosshatched area) and a portion
of the Thrust belt (modified from Maughan, 1984). Tensleep, Casper,
and equivalent potential reservoir rocks (inside dashed brown line)
modified from Mallory (1972). [Note: the GIS layer for the
Phosphoria TPS shows only that part of the TPS within the Hanna,
Laramie, and Shirley Basins Province.]
-
6
5
4
3
2
1
0
(4)
Type II-S high sulfur
Type II medium sulfur
Type II low sulfur
(1)
(2)
Dakota or Lakota Mowry and Thermopolis Muddy and Dakota Niobrara
Quealy Sundance Tensleep-Casper
(3)
0 10 20 30 40 50 60 70
API GRAVITY
SU
LF
UR
(W
EIG
HT
PE
RC
EN
T)