# # # # # # # # # # # # # # ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! Fargo Minot Bismarck Parshall Jamestown Dickinson Williston Bottineau Valley City Grand Forks Mandan Devils Lake Rugby Bowman Ward Dunn Cass McLean McKenzie Grant Morton Williams Stark Stutsman Wells McHenry Kidder Barnes Slope Walsh Mountrail Burleigh Sioux Benson Traill Emmons Pierce Dickey Richland Billings Logan Mercer Ramsey Nelson Adams Bowman Eddy Oliver Hettinger LaMoure Grand Forks Steele Sheridan McIntosh Sargent Griggs Ransom Foster Golden Valley Divide Burke Cavalier Bottineau Towner Rolette Pembina Renville ( / 85 ( / 85 ( / 2 ( / 2 ( / 52 ( / 52 ( / 83 ( / 83 ( / 2 ( / 52 ( / 83 § ¨ ¦ 29 § ¨ ¦ 29 § ¨ ¦ 94 § ¨ ¦ 94 § ¨ ¦ 94 JANUARY 2011 7 Potential Use of North Dakota Sand and Clay for Natural and Manufactured Proppants Fred J. Anderson The overwhelming success of the Bakken/Three Forks oil play in North Dakota can be greatly, if not wholly, aributed to the advances in hydraulic fracturing of “ght” reservoir rock. As part of the hydraulic fracturing process, proppants (commonly natural sands and manufactured ceramic spheres) are used to keep the fractures that are created open for the enhanced flow of oil and gas from the fractures into the wellbore. A typical hydraulic fracturing smulaon operaon in the Bakken in North Dakota requires anywhere from 100 to 500 tons of proppant per well: roughly 150 tons on average. The North Dakota Geological Survey has been invesgang North Dakota’s sand and clay resources in an effort to beer characterize deposits that could potenally be used as proppants. Specifically, we are aempng to locate useable deposits of sand (and potenally clays) for hydraulic fracturing and other industrial sand applicaons in the Williston Basin. Sand (and gravel) is widespread throughout North Dakota, although most is in the glaciated part of the state, where it is found in glaciolacustrine beach deposits, glaciofluvial (outwash) and modern stream deposits, and early to mid-Holocene dune fields. Most of the sand and gravel currently mined in North Dakota is used in construcon and road building. Synthec proppants are manufactured from a variety of materials and include aluminosilicate ceramics derived from the sintering of bauxite (aluminum oxide) and kaolinite. As part of our study, therefore, we are also looking at some of North Dakota’s kaolinic clays as potenal raw materials for the manufacture of ceramic proppants. Progress of Invesgaon Over 100 sand locaons were sampled from across the state for this study (fig. 1). We have idenfied the leading sand deposits based upon grain size, sorng, and roundness. Detailed sedimentological and engineering analyses are planned for the best candidate sands. Figure 1. The sand and gravel resources of North Dakota (yellow) and locaons of sand samples (brown dots) collected for possible use as proppants for the hydraulic fracturing of oil wells in the Bakken and Three Forks plays in the Williston Basin (modified from Anderson, in press).
4
Embed
Potential Use of North Dakota Sand and Clay for Natural ... and Clay for Natural and Manufactured Proppants Fred J. Anderson The overwhelming success of the Bakken/Three Forks oil
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
#
#
#
#
#
#
#
#
#
##
#
##
! !
!
!
! !
!
!
!
!
!
!
!!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!!
!
!
!
!
!!
!
!
!!
!
!!!
!!
!
!!!
!!
!!
!!
!!
!
!
!
!!
!!
!!!
!!
!!
!!!
!!
!
!
!!
!
!!
!
!
!
!
!
!!!
!
Fargo
Minot
Bismarck
Parshall
Jamestown
Dickinson
Williston
Bottineau
ValleyCity
GrandForks
Mandan
DevilsLake
Rugby
Bowman
Ward
Dunn
Cass
McLeanMcKenzie
Grant
Morton
Williams
Stark
Stutsman
Wells
McHenry
Kidder
Barnes
Slope
Walsh
Mountrail
Burleigh
Sioux
Benson
Traill
Emmons
Pierce
Dickey
Richland
Billings
Logan
Mercer
Ramsey
Nelson
AdamsBowman
Eddy
Oliver
Hettinger
LaMoure
GrandForks
SteeleSheridan
McIntosh
Sargent
Griggs
Ransom
Foster
GoldenValley
Divide BurkeCavalier
Bottineau
Towner
RolettePembina
Renville
(/85
(/85
(/2
(/2
(/52
(/52
(/83
(/83
(/2
(/52
(/83
§̈¦29
§̈¦29
§̈¦94
§̈¦94
§̈¦94
JANUARY 2011 7
Potential Use of North Dakota Sand and Clay for Natural and
Manufactured ProppantsFred J. Anderson
The overwhelming success of the Bakken/Three Forks oil playinNorthDakota can be greatly, if notwholly, attributed to theadvancesinhydraulicfracturingof“tight”reservoirrock.Aspartofthehydraulicfracturingprocess,proppants(commonlynaturalsandsandmanufacturedceramicspheres)areusedtokeepthefracturesthatarecreatedopenfortheenhancedflowofoilandgas from the fractures into the wellbore. A typical hydraulicfracturing stimulation operation in the Bakken inNorthDakotarequires anywhere from100 to 500 tonsof proppantperwell:roughly150tonsonaverage.TheNorthDakotaGeologicalSurveyhasbeeninvestigatingNorthDakota’ssandandclayresourcesinan effort to better characterize deposits that could potentiallybeusedasproppants. Specifically,weareattemptingto locateuseable deposits of sand (and potentially clays) for hydraulicfracturingandotherindustrialsandapplicationsintheWillistonBasin.
Sand (and gravel) is widespread throughout North Dakota,althoughmost is in the glaciated part of the state,where it is
found inglaciolacustrinebeachdeposits,glaciofluvial (outwash)andmodern stream deposits, and early tomid-Holocene dunefields. Most of the sand and gravel currently mined in NorthDakotaisusedinconstructionandroadbuilding.
Syntheticproppantsaremanufacturedfromavarietyofmaterialsand includealuminosilicateceramicsderived fromthesinteringofbauxite(aluminumoxide)andkaolinite.Aspartofourstudy,therefore,wearealsolookingatsomeofNorthDakota’skaoliniticclaysaspotential rawmaterials for themanufactureofceramicproppants.
ProgressofInvestigationOver 100 sand locations were sampled from across the statefor this study (fig. 1). We have identified the leading sanddepositsbasedupongrainsize,sorting,androundness.Detailedsedimentological and engineering analyses are planned for thebestcandidatesands.
MembersofNorthDakota’ssandandgravel-producingindustryarealsoparticipatinginthisevaluation,andseveral producers have submitted sand samplesfor consideration. The results of this study will becommunicatedtoindustrythroughpublicationoftheinvestigationresultsin2011.
We are also characterizing these samples for use in otherindustrial sandapplications includingwell completionmaterials(filter&gravelpacks),filtermedia, and foundrypractices. Theproduction of industrial sands as viable economic depositsgenerally requiresmaterials thatareusuallymoreconsistent incharacter, are available closer to the land surface, and requireminimal processing (screening and washing). Having a betterunderstandingofsomeofthecharacteristicsofourstate’ssandand clay resources is advantageous to both industry and thepeopleofNorthDakota.
ProppantCharacteristicsProppantsarecharacterizedbywhattheyare;thatis,theirphysicalproperties,andhowtheyperform(inbulk)withinthefracturedoil&gasreservoir; inotherwords, theirabilitytoenhanceandfacilitateflow(permeability)inaproppedfracture.Permeabilitymaybethoughtofastherate(distanceperunittime)atwhichafluid(oil,gas,water)canmovethroughaparticularsedimentorrock.Itiscommonlymeasuredincm/sec,feet/dayorthedarcy,after French engineer Henry Darcy, whose pioneering work onfluidflowledtothediscoveryofthelawthatisnamedafterhim(Darcy,1856).Texturallymaturesedimentsgenerallyhavehigherpermeabilities(fig.2)thanlesstexturallymaturesediments.Asa relevant everydayexamplehere inNorthDakota, theBakkenFormationexhibitspermeabilitiesinthemicro(10-6)darcyrange(Nordeng, oral commun., 2010). By comparison, oil and gasreservoirsworldwide typicallyhavepermeabilities ranging from5to500millidarcies(Selley,1998). Theonlywaytoliberateoilandgas froma “tight” reservoir like theBakken isbyhydraulicfracturing(fig.3).
Geologic factors such as reservoir depths, temperatures, andpressuresall relatetoaproppant’sability towithstandfractureclosurewithinthereservoir.Theclosurestrengthistheamountofstrainthatcanbetakenupbytheproppantbefore it failstokeep the induced fractures open during production from thereservoir. Whennaturalproppantsfail,particularitywhenusedin the Bakken Formation, individual sand grains may actuallyfracture under the high stresses and temperatures within theformation/reservoir (Vincent, 2010a& 2010b). These kinds ofgeologic factors are critically important to understand whendesigning fracingoperationswhere significant reservoirdepths,temperatures,andclosurestressesareanticipated.
Figure3.Schematicofanopen“propped”rockfracturewithproppantplacedwithintheapertureofthefracture.Proppantsthataremoreconsistentandwell-roundedasin(a),allowforgreaterinterconnectedporespaceandfacilitatealargeramountof flow (higher permeability) of oil and gas out of the reservoir rock and into thefracture(s) andwellbore. Proppants that are less consistent and have poor shapefactorsasin(b),(higherdegreesofangularity)tendtopackbetterbutresultinlessinterconnectedporespaceandlowerpermeabilities,whichresultsinlessflowofoilandgasintoandthroughthefracture.
Figure 2. Generalized relationships between grainsize and conductivity (permeability) of a sediment(modifiedfromShepherd,1989).
Figure 4. Outcrop of the St. Peter Sandstone near Ottawa,Illinois.Thehigherdegreesofsortingandmineralogicalmaturityof these Ordovician-age white “Ottawa” deposits allow fortheireconomicalproductionforuseasproppantsandinotherindustrialapplications.
JANUARY 2011 9
NaturalProppantsMostnaturalsandproppantsaresourcedastwotypes:“white”and“brown.”“White”orOttawasands(referringtotheirprimarysourceareaaroundOttawa,Illinois)(fig.4)areminedinpartsoftheupperMidwest fromquartz-richCambro-Ordoviciansandstonesthatarecharacterizedbytheirexceptionallyhighdegreesofpurityand textural maturity. These sands were originally depositedin a shallow marine environment where geologic factors suchas weathering, erosion, and repeated refinement in the surfzone have resulted in texturally mature sandstones that arecomposedalmostentirelyofquartz.“Brown”orBradysandsarefoundindepositslocatedinTexas.Becausetheyaresomewhatmineralogically and texturally less mature than Ottawa sands,Bradysandsarewashedduringprocessingtoremoveimpuritiessuchasclaysandfeldspars.Naturalsandproppants(figs.5aandb)areusedmainlyinshallowoperationswherefractureclosurestressesinthereservoirrockarerelativelylow.
BecauseNorthDakota’ssanddepositsaresogeologicallyyoung,theyaremuch lessmature,bothmineralogicallyand texturally,meaning that they consist of compositionallymore varied, lessrounded, less well sorted grains than most sands commonlyusedinhydraulicfracturing.Potentialproppantsandswillmostlikelybefoundinthebetter-sorteddeposits,whichtendtobeofwindblownorigin,liketheDenbighorPembinaDunes(figs.5cand6);orfluvialsedimentswheregeologicprocesseshaveselectivelyremoved someof the coarser and finer grained sediments (forexample,asandbar).
SyntheticorManufacturedProppantsSynthetic, ormanufacturedproppants aredesigned toperformunder specific reservoir conditions (high pressures andtemperatures coupled with high fracture closure stresses) andcanbeengineeredtoperformmorefavorablyinhostilereservoirconditions than natural proppants. Specialty aluminosilicateceramics, made from sintered blends of bauxite and kaoliniticclays, are one example (fig. 7). Several North Dakota clays,includingthosefromtheBearDenMemberoftheGoldenValleyFormation are being evaluated as potential candidates for themanufacture of these types of ceramic proppants. The BearDenMemberof theGoldenValleyFormation isamulti-coloredkaoliniticclaystonethatoutcropsinseverallocalitiesthroughoutDunn,Mercer,Morton,Mountrail,andStarkCountiesinwesternNorth Dakota (fig. 8). The Bear Den Member has been usedfor decades in the manufacture of bricks by the Hebron BrickCompany(Murphy,2009).
Oneofthekeydriversinproppantselectionanduseiscost.Naturalproppants,when appropriate and available, arguably provide amorecost-effectivesolutionthanacustom-designedandshippedsyntheticormanufacturedproppant.However,sincetheremay
Figure6.SanddunefromthePembinaDunesinnortheasternNorthDakota. Small-scalewind ripples are visible on the exposeddunesurface,indicativeofrecentwindactivity.
Figure 7. Photomicrograph of sintered bauxite ceramic proppantspheresusedinthehydraulicfracturingofoilreservoirs.Theuniformityof individual particle shapes combinedwithhighermaterial strengths,specific gravities, and thermogenic resistance have resulted in theextensive use of ceramic proppants (including this one) in Bakkenreservoir-relatedhydraulicfracturingandrefracturingapplications.
DevelopmentofProppantsinNorthDakotaWhetherornotaparticulardepositofsandorclaycanbeutilizedasasourceforproppants,dependsonseveraladditionalfactors,includingtheproximityofdepositsto locationswherehydraulicfracturingistakingplace,andthedegreeofnaturalbeneficiationin the deposit; that is, howmany natural cycles of refinementthedeposithasbeenexposedtoovertime.Forexample,ifthedepositistexturallyandmineralogicallymature,therewillbelessprocessing required to produce a given amount of marketablematerial(fig.9).Thisalsoplaysintocosts,asthelesseffortoneneedstoput intotherefiningof thedeposit, the lessmoney isspentbringing thematerial“uptospec”anddowntheroadtomarket. One current market-related aspect that is interesting(andtimely)isthefactthat,acrossthenation,theavailabilityofproppantsands fromtheirprincipalsourceareasappears tobedecliningasdevelopinggasplaysintheeasternU.S.increasetheirdemand.Inaddition,ceramicproppantswillmostlikelycontinuetobe imported into theWillistonBasin fromoverseasmarkets,asmoreanddeeperoilandgasdevelopmentoccursacrossthenation(Besler,oralcommun.,2010).
Since most, if not all, of the currently available natural sandresources are being shipped east for the stimulationof oil andgas reservoirs in Appalachia (especially the Marcellus Shale inPennsylvaniaandNewYork),operatorsintheWillistonBasinmaybewillingtotakewhatismostreadilyavailableandeconomicalas a bit of a frac-design/well production trade-off. Some havesuggestedthatoverallproductionfromBakkenwellsstimulatedwithceramicproppantsmaybeasgreatas30%higherthanthosestimulatedwithnatural(sands)proppants.
Overall, North Dakota’s sand, and possibly clay resources, arelocally abundant, readily available, and contain a sufficientvarietyofmineralogicalcharactertoallowforadiversearrayofpotentialindustrialapplications.Creativityinenduse,facilitated
by producers in industry, will drive the development of NorthDakota’ssandandclayresources. Withanestimatedneedof3million ormore tons* of proppants (around a couple of billiondollars at today’s prices!) to support full development of theBakken,gainingabetterunderstandingofourpossibilitiesfortheproduction of natural and manufactured proppants is prudentandbeneficialforallofNorthDakota.
ReferencesAnderson, F.J., in press, Locations of Sand and Gravel Sites in North
Dakota, North Dakota Geological Survey, Geologic InvestigationsNo.130,1:500,000scalemap.
Babcock, E.J., 1906, The uses and value of North Dakota clays, in theFourthBiennialReportoftheNorthDakotaGeologicalSurvey,
Vincent,M.,2010a, ImprovedProduction fromHorizontalWells in theBakken:2010NewHorizonsinOil&GasConference,SouthDakotaSchoolofMines&Technology,RapidCity,SD,Abstract.
Vincent, M., 2010b, A Study of 75 Refracs Performed in the middleBakken:2010NewHorizonsinOil&GasConference,SouthDakotaSchoolofMines&Technology,RapidCity,SD,Abstract.
Figure8.OutcropofthecolorfulBearDenMemberoftheGoldenValleyFormation in Dunn County. The Bear DenMember is found in severalareasintheheartoftheNDportionoftheWillistonBasinandisknowntocontainintervalsrichinkaolinite(Murphy,2009).
Figure9. Asandandgravelprocessingoperation innorthernBurleighCounty. This plant produces materials for a number of industrialapplicationsinNorthDakota.