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UNITED STATESDEPAR llmiT OF THE INTERIOR

GIDIOOICAL SURVEY

Interagency ReportMilitary - 2

mvmoNMENTS AT U. S. AND U S S R NUCLEAR EXP:WSIOll SITES:PETROLEUM-STIM JIATIOlf ~ T S

ByMaurice J . Terman

Sponsored byADVANCED RESEARCH PROJD::TS AGENCY

ARPA ORD B lfO. 1626

WASllm11Ulf D. c.1970

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Th eU n i t e d States P l o w s h a r ep r o g r a mf orthep e a c e f u l a p p l i c a t i o no fn u c l e a r e x p l os i ve s wa sf o r m a l l ye s ta b l i s h e d b ytheA tom i cEnergyC ommissionin 1957-A n u m b e r o fengineering us e sfors u c h e x p l os i onswe r ep r o p o s e d a n ddiscussedi nthelat e fifties,m o s t l y b yp e r s o n n e lo fthe Law rence Radiation. Jaborat ory u n d e rc ontr a c ttoAEC,a n dseveralpro ject s w e r es tu di e d indet ail d u r i n g the nu c l e a r we a p onste s tm o ra -t o r i u mextending f r om the f a l lof 1 9 5 8tothef a l l ofI 96J UThe f i r s tP l o w s h a r eexperiment,P r o j e c tGnome,wa sd e t o n a t e d on December 1 0 ,1961.S i nc ethat ti m e p h e n o m e n o l o g i c a l d a t ah a v e b e e no b t a i n e dinm a n y media,i nc l u di ng alluvium,tuff,shale,dol om i te ,salt,b a s a l t ,an d granite,w i t h e x p l os i onsatde p th sranging f r o m n e a r thesurfaceto a b o u t2,500meters.f t e rnegotiation b e t w e e nEl P a s o N a tu r a l GasC o m p a n y andAEC,the f i r s tJointindustry-government P lo w shareex p erimen t ,P r o j e c t Gas-buggy, wasd e t o n a t e d onD e c e m b e r10,1967.hes e c onds u c hexperiment.P r o j e c tR ul is o n ,c o n d u c t e d on S e p te m b e r 10,1969^u n d e r thes p ons or s h i pof Austral O i lCompany,Inc.,th eAEC,a n dtheDepart ment o fInterior,is c u r r e n t l y b e i n g evaluated.hese two e x p e r i m e ntsemphasizedtheU .S .i nte r e s tinthe p o t e n t i a la p p l i c a t i o n of undergroundclear ex-plosionstot hep e t r o l e u mindustry, 'especiallyto gasst imulationinsizabler e g i onsoflarge-scale,I g i r p r odu c ti vl ty ,g e n e r a l l yundevelopedresources, (h I I T J I I I I I > uwwl Tnthisr e p or t refersto b o t hgasa ndoilresources.)

TheUnion ofS ovi e tS oc i a l i s t R e p u b l i c sha sevinced c ons i de r a b l ei nte r e s tin then o n m i l i t a r yapplicationso f n u c l e a r energy,b t ' ; t heirparallel d e v e l o p m e n tofr e s e a r c h an de x p e r i m e n t a t i o nhasl a r g . . y goneunpubliclzed.he t ruee x te ntoft heir p r og r e s shasb e e ni ndi c a te dattheSoviet-Aierlcem te c h ni c a lt a l kso n theu se o f nu c l e a r e x p l os i onsf orpeaceful p u r p o s e sw hich w e r eheldx nVienna d u r i n gA p r i lI969a ndinMo s c o wd u r i n gF e b r u a r y 1970.he S o v i e t si de nti f i e dc r a t e r i n ga n d under-g r ou nd p r o j e c t sinan u m b e rofmedia,i nc l u di ng clay,shale,sandstone,limestone,salt,a ndgranite,w i t h explosions at de p th sr a ng i ng f r o mne a rs u r f a c e toa b o u t 1 , 500m e te r s .l lo f thei de nti f i e d u n d e r g r o u n dp r oj -ectsh a ve h a di ndu s tr i a lapplications^ h ffnllnyiTi

-aserieso f t h reee x p l os i ons( t w o \ e ve nts )as asecondary-recovery p r o j e c tinan e x p e r i m e nta l oi l f i e l d;

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T h es eex p erim entsa l s oem p h a s ize t h ep r i m a r y U.S.S.R.interes tInt h ep o t e n t i a la p p l i c a t i o n o f u n d e r g r o u n dn u c l e a r e x p l o s i o n s t o t he petro-l e u mindustry.

Thisp a p e rp r o p o s e sto b r i n g t o g e t h e rw i d e l y s c a tteredd a t ap e r t a i n -ingto a l l k n o w np e t r o l e u m - s t i m u l a t i o n p roj ec ts ,p a r t i c u l a r l y d e t a i l i n gthe e n v i r o n m e n t s a t s uc h sites.h e w o r k has b e e n s p ons ored b yt h eA d v a n c e dR e s e a r c h P r o j e c t s A g e n c y a ndm o n i t o r e db y Verne C .Fry kl und,Jr.Greata p p r e c i a t i o nisex p res s edf o rthec o n s i d e r a b l eh el pint her e s e a r c ha ndp r e p a r a t i o no f t he f i n a lrep ort t h a t hasb e e nof f ered b ym y a s s oc i-at esInt heU .S .G e o l o g i c a l Survey,b y J .WadeWa tkl nsa n d p e r s o n n e lo fthiDivision of P e t r o l e u m a n dN a t u r a l Gas,U .S .Burea u o fMines,a n db yRichard H a m b u r g e randp e r s o n n e l of t he Divis ion ofP e a c e f u lN u c l e a rEx-plosions ,U .S .A t o m i cE n e r g y Com m is s ion.


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N E E D F O R P E T R O L E U MSTIMULATIONT hep e t r o l e u mI n d u s t r yha sin v es t iga t ed nu m e r ou st ec h n iq uesf o ra p p l y i ng e ne r g y tor e s e r v o i r ro c ksina t t em p t st os ti m u l a te p r odu c ti on

a n din c rea s ethep e r c e n t a g eofrecovery.herateo f f l o wof afluidto aw e l lisdi r e c tl yp r o p o r t i o n a ltother e s e r voi rp e r m e a b i l i ty an dt h ic kn es s ,f l u i ddensity,a n dt h edi f f e r e nc eint h es t a t icres erv o irp r e s s u r e a n d f l owi ngw e l l b o r e pressure.he ra t eisi nve r s e l y pro-p o r t i o n a lt of l uid vi s c os i ty ,c o m p res s ib il it y ,an dthel og a r i th m oft h e r a ti o o fthedr a i na g er a di u sto we l l b or eradius,herefore,a nincreaseinrate of f l o wc a n b e a c h i e ve db yi n t r o d u c t i o nofa ddi ti ona lf l uid s(flooding,et c.)toi nc r e a s e res erv o ir pressure,b y"treating"th e r e s e r v o i rrockst oi nc r e a s e p e r m e a b i l i ty a n d t h e e f f e c ti ve radiuso fthew el l b o re ,orb y h e a t i n g t hep e tr ol e u mto l o w e ritsviscosity."Trea t men t s"tr a di ti ona l l y r a ng ef r o m acidizingc a r b o n a t eres erv o irstof r a c t u r i n gc l a s t icres erv o irs;f r a c tu r i ngo r i g i n a l l y w a s accom-p l i s h e db y s h o o t in gw i t hs o l i d i f i e dn it ro gl y c erin ,a ndm o r erec en t l yb y h y dr a u l i cf r a c tu r i ng w h e r ew a t e r andsandar ep u m p e din t o thereser-v o i r u n d e r p r e s s u r e s u f f i c i e n ttop r odu c e af r a c t u r eth a tist h enh e l dop e nb y theinjecteds a n d gra in s.a x i m u m in it ia li nc r e a s ein produc-ti onisa p p r ox i m a te l y f i v e f o l d b y s h o o t in ga n d t e n f o l d b yhyd ra ul icfra c t urin g ,b ute x p e r i e nc es h owst h a t these ra t ess u b s e q u e n t l ydecline.The p e t r o l e u mi ndu s tr ythew o r l da r ou ndo b v i o u s l yr e c og nize sthepoten-t ia l o f u nde r g r ou nd n u c l e a r e x p l os i ons as l oc a le n e r g y s o urc esx ' o rp o s s i b l es ti m u l a ti ono f p r o d u c t i o na n d i nc r e a s i ngu l t i m a t er e c ove r yper-c en t a ges.

U N I T E D S T A T E S G A S - S T IMU L A T I O N P R O J E C T SU n d e r g r o u n dnu c l e a r e x p l o s i o np h e n o m e n o l o g yis d o c u m e n t e df r om

th e m o r e th a n200 t es t s( U .S .A tom i cE ne r g yConm i s s i on,1969a)sinceth e d e t o n a t i o nof the l . f - k i l o t o n R a i ni e re x p l os i onin S e p te m b e r1957.S equ e nti a lschematicdi a g r a m so f this p hen o men o l o gy ,b a s e d o n d a t af r o mtheG a s b u g g yProject,a res h o w ninFigure 1 .hee x p l o r a t o r yan d em-p l a c e m e n tw o r k c u l m i na te sw i t ha ne x p l os i onw h i c h c r e a te sasphericalc a v i t y b y va p or izi ngt hee n c l o s i n gr oc kat e x t r e m e l yh i g h t em p era t uresa n d p r e s s u r e s(ove r te n m i l l i o nde g r e e s a ndonem i l l i o na t m o s p heres) ,a n d g e ne r a te se x tr e m e l y s t r o n gc om p r e s s i ona ls h oc k w a v e s(fig.la).hec a v i t y ex p a n d su n t i lt hega sp r e s s u r e equals th el i t h o s t a t i c p res s ure(approximately 230 g/cm^ f o r e a c h m e t e rofd ep t h)ass h o c k w a v escon-ti nu et otr a ns m i t e ne r g yin t ot h es u r r ou ndi ngrock,i n i t i a t i n g w it hinita n e x te ns i vea ndi ntr i c a ten e t w o r k off r a c tu r e s(fig.lb).i th i nthe cavity,ther o c k v a p o r c o n d e n s e s an d them e l trunsd o w nthesidesto c o l l e c tin ap u ddl e o nt h e f l o o r(fig.1c). f e w s ec o n d stominutes,r a r e l y h ou r so r days,a f t e r t h eexplosion,the c a v i t y p r e s s u r efallsb e l o w ac r i ti c a lva l u ea n d t h ef r a c tu r od roofr o o k n o r m a l l y startstoc ol l a p s einto the cavity,and,w i t h i n afewseconds ,a l a r g egen era l l yc y l i ndr i c a l c h i m ne y o f b r o k e nr o c k d ev el o p su p w a r dtowa r dsth esurface


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u n t i l the r o u n d e dr o o fr o c k b e c o m e ss tr onge nou g h tosupport I t s e l f o ru n t i lb u l k yb r o k e nr o c kfillsthevoi da nds u p p o r t sther o o f(fig.Id),Co n s i d e r i n g this p h e n o m e n o l o g y ,thep h y s i c a l e f f e c t s th a t n ee d t o b ec o n s i d e i e dinr e l a ti on top e tr ol e u m - s ti m u l a ti onp r o j e c t s a r e f r a c t u r i n g ,hea ting ,r a d i o a c t i v i t y ,a n d s eis mic ity.

TheA m e r i c a n p h i l os op h i cp os i ti on a n dt e c h n i c a lc r i t e r i aa p p l i -c a b l e tos t i m u l a t i o n w e r ei n v e s t i g a t e da nd we l l d e f i n e db y A t k i n s o n a n dJoh a ns e n in1964.i e y ( . - c n c l u d e d th a tp r o d u c t i o n Increases c a u s e db yth ef r a c tu r i ng of thick,l o w permeability,na tu r a l ga s reservoirs a tm o d e r a t e d e p t h s a p p e a rt o b et e c h n i c a l l y a n d e c o n o m i c a l l y f e a s i b l e a n dp ote nti a l l yc a p a b l e o f r a i s i n g s u b m a r g i n a l r e s o u r c e s t oc o m m e r c i a l l e v e l s ,w h e r e a s p r odu c ti on i n c r e a s e s causedb y the h e a t i n g ofo ilr e s e r v o i r sa p p e a rtob e di s a p p oi nti ng l y s m a l la nd u n p r o m i s i n g.o n s i d e r a b l e s u b s e -q ue n te m p i r i c a l d a t aa nds e v e r a l ong oi ng a n dp r op os e d P l o w s h a r ep r o j e c t sa l l tend to s u b s t a nti a te t h e s ec onc l us ions.hen v i r o n m e n t a l da taf o rt h e s eUnited States p r oj e c ts ar e rummarlzedI n D a b l e 1 .hec u r r e nts t a t eo f k n o w l e d g es u g g e s t st he f o l l o w i n g di s c u s s i on o fthe specifice f f e c t sof u nde r g r ou nd nu c l e a r explosions asr e l a te d tog a s - s ti m u l a ti onp rojec ts.F r a c tu r i ng

The s p a t i a lr e l a ti ons h i p s of b r o k e n a n ddi s p l a c e d r o c k c r e a t e d b yc o n t a i n e d e x p l o s i o n s h a ve r e c e ntl y b e e n r e vi e w e d b y Boardman(1970);h isd a t a i n v o l v i n go n l yt y p i c a lh y d r o c a r b o n r e s e r voi r rocks,s e di m e nta r yc a r b o n a t e san d f i ne - g r a i ne d elastics,a r ep r e s e n t e d I nT a b l e2.N ota -t i o n s an dt hem e t r i c u ni ts used t h r o u g h o u tthis p a p e r a realsod e f i n e di n thistable).i ef o l l o w i n gc h a r a c t e r i s t i c s p e r ta i ni ngtohy dro-c a r b on s t i m u l a t i o nar ea b s t r a c t e d f r omBoardman*se x c e l l e n tr e vi e w un -l e s so t h e r w i s enoted.

1 ^ , Theb a s icp a r a m e t e rf r o m w h i c h a l loth e r s a r e d e r i v e disthec a v i t yra dius.hera diusof v a p or iz a ti on Is estimateda ta b ou t 2m e te r sf o r a 1 - k t e x p l os i onb u t t h ef i n a l c a vi tysizee x c e e d ss u c h a s c a l edv a l u eb e c a u s e o f a d d i t i o n a l m e l t -in ga n dm e c h a ni c a leffects.l g g l n s a n d B u t k ovi c h (1967)d e v e l o p e d ade f i ni ti ve .scalingequation:C W: L/3Rc =TTW 1 )where C ,t hel l t h o l o g yc ons ta nt,ha s b e e n de te r m i ne d In46 nu c l e a re v e n t stoa p p r o x i m a t e8 9 f o r a l l u vi u m(30events)anddol om i te(l),9 6f o r salt(2),9 7f o r tu f f(11),a n d103f o r g r a n i t e(2);W is they i e l dIn k l l o t o n s ; ^ist heo v e r b u r d e n d e n s i t yi n g/cc;h Is th ed e p t h o fburial;a n d thea d i a b a t l ce x p a n s i o n c o e f f i c i en t ,v a r i e s wi th thewa terc onte nt f r o mabout 0.25 toO.33.i g u r e 2s h owsther e l a t i o n s h i p sof yiel d,depth,a n dc a v i t y radius f o ra


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g r a n i t e m e d i u m .or s h a l l o w ( l e s st h a n 6 0 0 m e t e r s ) c o n -t a i n e d e x p l o s i o n s ,t h e s i m p l e c u b e - r o o t e n e r g y s c a l i n ge q u a t i o n ( B o a r d m a n ,1 9 7 0 ) a p p e a r s a d e q u a t e :y/3 2 ) e -cw h e r e C c, t h e l i t h o l o g l c c a v i t y c o n s t a n t ,a p p r o x i m a t e s Sforc a r b o n a t e r o c k s ,1 1 . 5 f o r g r a n i t e ,1 2 . 3 f o r s a l t , 1 3 f o rc l a s t i c r o c k s a n d h a s t h e o r e t i c a l v a l u e s a s h i g h a s 1 5 .h cg r e a t e r t h ed e p t h o f t h e s h o t p o i n t ,t h e s m a l l e r t h ec a v i t yb e c a u s e o f t h e greater l i t h o s t a t i c l o a d .he e f f e c t o fd i f f e r e n t l i t h o l o g l e sa n d d e p t h o n f i n a l c o n f i g u r a t i o n s i ss h o w n i n F i g u r e 3 .

oh T h e c h i m n e y r a d i u s I s a s s u m e d t o a p p r o x i m a t e t h e c a v i t y r a d i u s ,b u t s o m e o v e r b r e a k i s e x p e c t a b l e a l o n g t h e s h a t t e r e dc h i m n e yw a l l s ; m e a s u r e m e n t s atv a r i o u s d i s t a n c e sa b o v e t h e s h o t p o i n t( 5 6 . 5 m e t e r s i n t h e H a n d c a r c h i m n e y )h a v e b e e n m a d e f o r t h r e ep r o j e c t s , a v e r a g i n g : Rc h " Rc 3 )

B ^ j j jheh i m n e y h e i g h t i n e l e v e n p r o j e c t s h a s t h e f o l l o w i n g r e -l a t i o n s h i p :S c h - Cch Rcw h e r e C . ,t h e l i t h o l o g l c c h i m n e y c o n s t a n t ,s t a t i s t i c a l l ya v e r a g e s k.kn d r a n g e s f r o m 3 . 2 t o 6 . 2 ; a few r e a s o n a b l ea s s u m p t i o n sb a s e d o n l o c a l g e o l o g i c v a r i a b i l i t y a t t h e s i t e sn a r r o w t h e v a r a b i l i t y ,s u g g e s t i n g a v a l u e o f 5 . 7 + 0 . 6 w i t ha p r a c t i c a l u p p e r l i m i t o f b e t w e e n 6 a n d J.

V Q J J H i e b u l k i n g c h a r a c t e r i s t i c s o f t h e d i f f e r e n t r o c k s c r e a t ed i f f e r e n t p e r c e n t a g e so f v o i d s i n t h e v a r i o u s c h i m n e y s ; 2 5p e r c e n t p o r o s i t y a p p e a r s t o b e a n e x p e c t a b l e v a l u ei n m o s tr e s e r v o i r r o c k s .heo i d v o l u m eo f b o t ht h e i n i t i a l c a v i t ya n d t h e f i n a l c h i m n e yi sd i r e c t l y r e l a t e dt o y i e l d :

V c = CVW 5 )w h e r e Cv, t h e l i t h o l o g l c v o i d c o n s t a n t ,a v e r a g e s 3 f o rt h e r e s e r v o i r r o c k s a n d C U Bh i g h a s6 . 2 f o r g r a n i t e s .A sw i t h t h e c a v i t y r a d i u s ,l o w e r v a l j e s c a n b e e x p e c t e d a tg r e a t e r d e p t h s .h e r u b b l e v o l u m e y l c h i n t h e f i n a lc h i m n e yh a s b e e n e v e n m o r e highly v a r i a b l e i n past p r o j e c t s , b u tt h i s w o u l d h a v e m u c h l e s s e f f e c t o n a petroleum s t i m u l a t i o ne x e r c i s e t h a n t h e p a r t i c l e s i z e d i s t r i b u t i o n o f t h e r u b b l e .


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. h e datafrom t h e Handcar project,derivedfrom downholephotographsi n dolomite r o c k ,indicate:ewofthefrag-mentswerelargerthan 1 m o rsmallerthan1 0 cmindiameter;65 percent were lessthan 3 0 cm and80 percentweremore than15 cm i n diameter;and t h e median particlesizewas between 20and25c m .abb( 1 9 7 0 ) estimatesf romPiledriverdatat h a t the typical?artlcle-slzedistributionforhardrock wouldbea p p r o x i m a t i i l y 8 0 percentless than1 m withthemedian about 3 0 cmandthebulk ofthe parti-cles(65-75 percent)between 3 and90c m .here shouldbeconsiderabledifferencesbetweenrocktypesandwithinafew metersinonerock t y p e ,b utthecombinationof veryfewlargebouldersandalmostnofines i s favorableforfluidorgaseous movement.

Rf A tsomeoftheearly explosionsites,observationsoflateralfracturingIndicatedasimplecube-rootenergyscalingequationforthecalculationof t h e radiusoffracture;

Rf O 6 )AtoneofthesitesstudiedmostIntensively,t h e FrenchHcggartest site i n Algeria,Derllch( 1 9 7 0 ) gives thefracturezoneradius i n granite a s 26 wV 3.tkinsonandJohansen (1964) suggested, h a tthepreexisting planesofweaknessin mostreservoirrockswould permita new fracturepatterntoextendf a r t h e r ,andthus estimated:

R f = 6 5 w V3 7)Byubstitution fromequation ( 2 ) andusing 9 for thelithologic constant,theseequations indicatethattheradiusof fracture wouldbe about4.5R . ,2.9 R c ,and7.2Respectively.llcurrentdiscussions recognize,howevir,thatthevolumeoffracturedrock i snotsphericalbut morenearly cylindrical,asfollows:

f, . Thehelgntthatexplosion-inducedfractures extend aboveashot pointhasbeenestimatedas( 7 + 1)1 ^ 8)

Thisi s supportedby theHandcar data and i s indicatedattheGasbuggys i t e b y casing disruptionsatscaleddistancesof5.2Randf.2 1 ^ , .nthreetestsingraniticrocks,t h e valuesrangedfrom6.9 t o 7.6 I ^ , .


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D - Thedepth o f fractures below a shotpointhas notbeengenerally observed,butforsometimehas beenestimateda tDf=1.5R c 9 )

H o w e v e r ,recentdatafromtheGasbuggy site( H l z e r ,1970)Indicate that theextent o f fractures belowt h e s h o t pointwouldbequite similart o theextentoflateralfracturesa s citedbelow.L ^ , T h e lateralextent o f fractures froma shot poivt hasbeenestimateda suf

Lf =( 3 + 0.5)R c 1 0 )Observations of movement i n preexisting openingsIndicatefracturesextend t o5 R c a t the Shoal siteand t o 6 R j ,att h e Hardhatsite,b utsuch movementsmay beduet o inter-facereactionwi thshock wavesandmaynotreflect t h e trueextentofcontinuous f r a c t u r e s ; moredata areneededtoclarifythese field relationships.

Vf T h e minimumv o l u i r - of t h e rock massthati s fracturedmightbeapproximatedb y assumingacylindrical form and s u b -stitutingfromequations( 8 ) ,( 9 ) ,and( 1 0 ) :Vf = 0.24R3 1 1 )

i f thevolumei s expressed i n thousands ofcubicmeters.Assuming thatthefracture pattern weresphericalforasimilar volume,theradius ofthespherewouldbeRf-3.87R c 1 2 )

T h i s relationshipappearsmore likelythanthatderivedb y eitherequations( 6 ) or ( 7 ) .lso,b y substitutingfromequation( 2 ) ,thefollowingrelationships can bederived:

Rf= 3 5 W1^ 3 . 3 )Vf=175W Ik)a n d

Notethat i f thelithologic constant i s taken at i t smaximumsuggestedvalueof1 5 ,thenthevolumewouldapproach 87O W ;t h u s ,thevalueoft i ; lithologicconstant i s critical.


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P r e c i s eq u a n t i t a t i v evalues f o rth e s e ex p res s io n s c a n n o tb ed e r i v e df r om thee x i s t i n g em p iric a l data;thea d d it io n a l o b s e r v a t i o n a lfactstob ed e r i v e df r om theG a s b u g g yan dR u l i s on pro j ec t ss h o ul d d o m u c hto c l a r i f y relationships.

F r o m thea b o v e discussion,af i r s t a p p ro x im a t io n o fthep a ra -met ricv a l uesf o ra typicaloil o rgasres erv o irr oc k m i g h tb esum-marized asinT a b l e3 andF i g u r ek. A sa l it h o l o gicc o n s t a n tisu ti l ize dina l m os t ev ery equation,th en a t ure of thes u r r o u n d i n gr oc ki sof greatimportance.hee m p i r i c a l d a t ad eriv edats it esin v a rio usm e d i ah a v e b e e n a m p l ifiedb y a specificex p erimen tthatw a sc o n d u c t e das p a r t oft h eGn o mep r o j e c tinI96I. n um b erofs m a l lr oc k samples ,i nc l u di nge l a s ti c s a n dc a rb o n a t es ,w e r e s ub j ec t ed to s h o c k p r e s s u r e sr a ng i ng f r o m 3.7to6.ki l ob a r s c r e a t e d b y the 3.1 - k i l oton n u c l e a re x p l os i ona t ade p thof 361 m e te r sin b ed d edsalt.her e s e r voi r - r oc k sample b e h a v i o r has b een w e l ld e s c r i b e d b yC o f fer an d o t h ers(196^):s ta ti s ti c a la n d gra p hic a l d a t a m o d i f i e d f r o m t heir report,c o m p a r i n gp h y s i c a l p r o p e r t i e s o fs h o c ked a n du n s h o c k e d samples,a rep r e s e n t e dinT a b l ekn d F i g u r e5 .e vi s u a lef fec tofthe n u c l e a re x p l os i onon thes a m p l eswasn otdramatic ,p r o d u c i n gnoa p p a ren t p l a s ti cdefor-mation;the e l a s ti c sphowedo n l y s l i g h tincreasesin fria b il it y ,b u tthe c a r b ona te sex hib it ed a c o n s i d e r a b l en e t w o r kof ma c ro -an dmic ro -fractures.h ep or os i ty o f th e e l a s ti c sshowednos i g ni f i c a nt change,wh i l et h a t o fthec a rb o n a t es g e n e r a l l yIncreased^fig.5 c ,d).hep e r m e a b i l i t yo ftheel a s t ic se x h i b i t e d a gen era ldecrease,w h i l e t h a to ft h e c a r b ona te sI n c rea s ed d i r e c t l yw i t h a nincreasein s h o c kp res -s ure(fig.5 a >b ) .he corapressives tr e ng th ofb o t hm a j o r r e s e r v o i rro c ktypesg e n e r a l l ydecreased.hes h oc k p res s ure a l s oI ni ti a te db o t hc r a c k i n g a n d p ol y m e r iz a ti on ina s m a l l p e r c e nta g e o f the o ilsamples;t h ede g r e e andr e l a ^i ve p r o p o r t i o no fcha n gea p p e a rt o b e af u nc ti on ofth en a t ure oft hecrude,an demphasizet h a to n l y as m a l lf r a c ti onoft h et o t a lr e s e r voi ro il sin the v ic in it yof an u c l e a r ex-p l o s i o n w o u l d b eaffected.l t h o u g h a d m i t t i n gt h a tth e n u m b e r ofs a m p l esw e r e f e wa n d that t h ef u l l r a ng e of ex p l o s io n e f f e c tsw a sn o ttested,th e a u th or ste nta ti ve l yc o n c l u d ef r o ma v a il a b l ee v i d e n c ethatc a r b ona teres erv o irs ,ando t h ers w h i c h de f or m b yb r i t t l efra c t urin g ,a re p r o b a b l y t h em os t s uit a b l ec a n d i d a t e sf o r s ti m u l a ti onp ro j ec t s.

The a b o v ep h e nom e na are d i r e c t l y rel a t edtotwoa s p e c tso fh y d ro -c a r b o n - s t i m u l a t i o np ro j ec t sin t h a tt h e ya f fec tr e s e r voi rp e r m e a b i l i t yandf a v o r s e l e c t i o nofres erv o irs w i t h g i ve ngeometricrel a t io n s hip s.

E f f e c to nr e s e r voi rp e r m e a b i l i t yT hen u c l e a rex p l o s io np h e n o m e n o l o g y d es c rib ed a b o v e c r e a te sa n d

i nte r c onne c tsvoi ds andth e r e b yi nc r e a s e sthe p e r m e a b i l i ty o ft h es u r r ou ndi ng rocks.hep e r m e a b i l i ty o ftherubblein an u c l e a rc h i m ne yi senormous;p r e s s u r iz a ti on testsi ndi c a tethatitg e n e r a l l y res p o n d s

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l i k ea l e a k y t a n k a n dreactstoa p r e s s u r e p u l s e likea no p en cavity;thus,f l u i df l o ws h o ul d h a vel i t tl eres is t a n c e.ode a n(Boardman,1970)es t im a t edth e p e r m e a b i l i t yv a l ue of4x 105 darciesf o rthec him n eyr u b b l e a tth eH a rd h a t site;o rigin a lin situmea s uremen t sinthe g r a ni te we r e as l o w as10"5 darcies ,i n d i c a t i n ga m a x i m u min c rea s ea p p ro a c hin g1 0ordemofmagnitude.he p e r m e a b i l i t yof ther o c k sur-ro un d in gthe c h i m ne y c h a n ges b ec a us e o ft h es h o c kpressuresex ert eddu r i ngthe g r o w t ho fth e cavity.i g u r e6I l l us t ra t esthe d a t a de-rivedf or p e a k c o m p r e s s l v estressInd i f f e r e n tm e d i ave r s u ss c a l edradius.u c h p r e s s u r e sc r e a tec h a ng e sinm a t r i xpermeability,b e d d i n gpermeability,a nd f r a c t u r e p ermea b il it yp o s s i b l y noo s ep a ra b l einsomer e s e r voi r sw i t h the grea t es tc h a n gesres ul t in g fro m the de-v el o p men to f a n I n t ric a t e n et w o rk offra c t ures.het ot a l res ul t ofa l lchanges has b e e n m e a s u r e de i th e rins i tu o r incore samples ,o rb y noti ng dr i l l i ngf l u i d losses a ta n u m b e ro f sites;s u c h da ta h a v eb e e nused t od e r i v et h e ex t en tof f r a c tu r i ng asi ndi c a te din thep a ra -metricvaluesg i v e nin T l a b l e 3 .he s p a t ia l v a r i a t i o n infra c t urep e r m e a b i l i t yhasb e e nmea s uredind et a il o n l y atthesitesingra n it icrock.a t af r o mt h e H a rd h a tsiteg i v e nb y B o a r d m a n and S k r ove(1966)ar eshown g r a p h i c a l l y i nFiguref: I m m e di a te l y a d j a c en t toa n d v eryn ea r the c h i m ne yb o u n d a r i e sp e r m e a b i l i t yoft h es h a t te r e dr o c ka p p r oa c h e ds e v e r e d , darcies ,w h i c h w as as m u c has5 o r d e r so f m a gn it ud eg r e a t e r t h a nthel ow e s trec o rd edin s it umea s uremen t s o f s e v e r a l 10"5darcies;s uc hhigher l e ve l so f c h a ng e w ere note d f o r a b o u t2jR fro mthe v e r t i c a laxisofthe chimney,a n d l o w er levelsm a y e x t e n dasfaras6R l a t era l l y an d 1.2 R , ,b e l o w theshot point;a n d mea s uremen t sofpre-shotandp o s t - s h o ts a m p l es b y Short(1964)in d ic a t e t h reef o l do rf ou r -f o l dincreasesint h em a t rix p e r m e a b i l i t yo ft h eg r a ni ti cr oc k(1 2 t o44mic ro d a rc l es)u p t o d is t a n c es of1.8 R a t a fro m theA l g e r i a nH b gga r tests i teg i ve n b yDelort and S up io t(1970)a re s h ow n g r a p h i c a l l yinF i g u r e8:hep r i nc i p a l c a te g or i e sm a r g i n a lto the c him n ey ar ein-creasesof120xt o2. 8 R ,12x to3.7 Rc,8 xto5 1 ^ , ,and6x t o5.8 j ,fro m thein s it up e r m e a b i l i t yof5 md.nth e b ed d edsaltd ep o s it sa tthe Gnomesite,m o s t o f theincreaseinp e r m e a b i l i t yisrelatedtop a rt -i ng a l ongb e d d i n gp l a n e scaused b ythet e m p o r a r y up l if t of theb e d so v er the ex p l o s io n site.e r m e a b i l i t yd i s t r i b u t i o n so fthes it esingra n it e an d theG n o m es i teinb ed d eds a l ta r ep r e s e n t e dinF i g u r e 8 a tthe same scaleasu s e d p r e v i o u s l yinF i g u r e1f o r the Ga s b uggy s i teina b ed d ed clasticsequence;it isa n t ic ip a t edt h e l oc a lgeologicp hen o m -e na w i l lh a ve c o n s i d e r a b l eeffectof fin a ls p a t i a lc o n f igura t io n ofp e r m e a b i l i t yincreases.

Thea x i m u m ra t io s o f p e r m e a b i l i t yva l u e s f r o m or i g i na lr o c k toex p l o s io n -a f fec t ed r o c k toc him n eym i g h t b eo n t h eo rd ero f 1t o 10^t o10^.h e G a s b u g g y r e s u l ts(Hblzer,1970)s h o w n o suchd ra m a t icchanges,b u tin d ic a t eo n l yap o s s ib l e100- f ol di nc r e a s e tod is t a n c eso fonec a v it y radius.n them os t c o m m o n r e s e r v o i r rocks,itis m or el i k e l y thatth em a g n i t u d eof the t ot a lin c rea s einp ermea b il it y f r o ma llchangesin the a f f e c te d a rearangesf r o ma b o u t three-fold,as a t


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theH a n d c a rsite(several h u n d r e dm i l l i da r c i e sto 1 darcy),toa b ou tfiv e-f o l d ,asa t theG a s b u g g y s i te(0.01to0.05md.).s m u c hoft h isi nc r e a s ei s dueto m i c r o- f r a c tu r i ng ,the p e r m e a b i l i t y c h a n gesw il lb em os t p r onou nc e dasr e l a t e dtoincreasesingas p r o d u c t i o nra t esr a th e rtheminoilp r o d u c t i o nrates.r a nk a n d oth e r s(1970)r e vi e wtheef fec t of di f f e r e ntsize d ev ic eson gasr e s e r voi r s w i t hd i f f e r e n to rigin a lp e r m e a b i l i ti e s(fig.9)andp r e di c tt h el o n gra n gei nc r e a s e sinu l ti m a ter e c o v e r yp erc en t a ges;t h e y i ndi c a tea b o u ta f i ve - f ol dincreaseinu l t i m a t er e c ove r y fo r Pr oj e c tRulison.tk i ns ona ndJ o h a n s e n(196^)stressone m a j o r qua l i f i c a ti ont o t h eef fec t iv en es softhisp hen o men a:he u n c o n t r o l l e dfra c t ures p r o d u c e db y anu c l e a re x p l o s i o ninawa te r - dr i ver e s e r voi r c a n beex p ec t edtoa f f e c tul t im a t er e c ove r y adversely,ass i g n i f i c a n tp a r ts oftheo i l r e s e r ve s m a y b e b y-p a s s e d b ythedi s p l a c i ngwater.n o t h e r qua l i f i c a ti onisrel a t edtotheo r i g i n a lp e r m e a b i l i tyva l u e sinares erv o ir rock:fiti st oolow,e v e n ex t en s iv ef r a c tu r i ng m a y n o timproveit s u f f i c i e n t l y toc r e a tec om m e r c i a lp r o d u c t i o n rates. fin a lq u a l i f i c a t i o nist h a t them a x i m u m d e p t h towh i c hf r a c tu r e s w i l lrem a in op e n s u f f i c i e n t l yt oassistinp e t r o l e u m p r odu c ti oni sun kn o v n .

L a b o r a t o r yp e r m e a b i l i ty va l u e sc a n b eus edasa g u i d eto thea m e n a b i l i t y to s ti m u l a ti onof g asreservoirs,o r s ol u ti c n- g a s - dr i veoilres erv o irs ,atnor m a l d ep t h s.e s e r voi r ro c ksr a ng e f r o m t ho s ew i t h e x t r e m e l yl o w v a l ues(lessth a n 0.001 md.),w h e r es ti m u l a ti onw o u l d b eimpracticable,tocnosew i t h valuesc o m m o n l yf o u n dincommer-c ia lfiel d s ,w h eres ti m u l a ti onw o u l da p p e a run n ec es s a ry.o m ew hereinthei nte r m e di a tevalues,a no p t i m u m p e r m e a b i l i ty ra n gee x i s tsinwh i c hu ne c onom i cl o w p r o d u c t i v i t yc o u l db eimproved b y e x p l o s i o n - i n d u c e dfrac-t uresi nc r e a s i ngp e r m e a b i l i ty a n dp r odu c ti vi ty toac om m e r c i a l level.Theg a s - s ti m u l a ti on p r oj e c tsinth e U .S . ,ass h ownin F i g u r e1 0 ,indi-cateac u r r e n tb el ieft h a tthiso p t i m u m valuel iess om e wh e r e b e t w e e nc o re de te r m i na ti onsof0.1to 1 .0mil l id a rc ies.t i e c or e de te r m i na ti onsa ve r a g e a b o u t0.15md.a tth eG a s b u g g y site,0.25md.a tWa g o nheela n dWASPsites ,0.5 md.attheR u l i s o nsite,and1.3 md.a tt h eDragon Tra ilsite.owever,thein s i tup e r m e a b i l i t y a ttheG a s b u g g y s it e hasb e e nde te r m i ne db yo t h er m e th odstob el es sthan 0.01 md.;e v e nift helab-o r a t o r y de te r m i na ti onsa re a n o r d e ro fm a gn it ud einerror,t h eystilla rei ndi c a ti ve ofr e l a ti ved i f f e r e n c e sin the c o n d i t i o n s a t va r i ou ssites.

The k n o w nin t erimres ul t so ftheGa s b uggy p r o j e c t(Hlzer,1970)a p p e a rtoJustify thep o s i t i o n th a tp r odu c ti on f r o mthick,l o w perme-a b il it y ,na tu r a l gasr e s e r voi r sa t m ode r a te depthsc a n b es ign ific a n t -l y s t i m u l a t e db y u nde r g r ou nd n u c l e a r explosions.he 1 7 - m o n t h cumu-l a ti ve p r o d u c t i o nh i s tor y of ga sf r o m t hereen t ry well,GB-ER,s h o w ninF i g u r e11,emphasizest h a tG a s b u g g y has a l r e a dyp r o d u c e d m or ethant w ic e asm u c hgasas an yof f i ve c onve nti ona l we l l sw i t h i n l km,an df l owra t eex t ra p o l a t io n si ndi c a teaf i na lp r o d u c t i o nc a p a b i l i t yof5to8ti m e sthatofa nyofthec o n v e n t i o n a lwells.

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Effect o n r e s e r v o i rgeometryThea g n i t u d e of thefracture p a t t e r nof a nucleare x p l o s i o n

requiresa m i n i m a l prefera blet hicknesso fth ereservoir.u c l e a r -explosionf r a c t u r i n g a l s o m u s tc o m p e t ew i t h c onve nti ona l h y d r a u l i cfracturing asaneffectivea ndinexpensives ti m u l a ti on m e t h o df o rreservoirs. m i n i m u mnet -payt h i c k n e s sof a b ou t60meters(200f e e t)wassuggested b y A t k i n s o n andJ o h a n s e n(1964)fore c o n o m i c a l l yf e a s -ible n u c l e a r m e th ods .igure12s h owst hata l lUnitedS ta te s p r o j e c t sexceedthis minimum:as buggy r e s e r v o i ris 8 8 . 4 meterst h i c k w i t h58metersof g a s - b e a r i n g sands;Dragon T r a j lreservoirisa b o u t90to150m e t e r st h ic k;a n dRulisonr e s e r v o i risa bout760m e t e r st h i c k w i t ha b ou t1 50m e t e r sofg a s - b e a r i n g sands.

Them a g n i t u d e ofthefracturep a t t e r n s i m i l a r l yrequirest hatthenucleard e v i c em u s t b e b u r i e da ta d e p t h s u f f i c i e nt top r e v e n ta n ysurfacev e n t i n g ofradicactivity.a n s e nan dLombard(1964)s u g g e s tthatfo r e x p l o s i o n sinh a r d rock,v e n t i n g c a n bep r e v e n t e db y ad e p t hofb u r i a lequaltoth e ant icipated c h i m n e yheight plus a 90-t o150-m e t e rt h i c k"b u f f e r"ofo v e r l y i n grock.u ch a scaledc o n t a i n m e n tde p th(Z in m e t e r s )w o u l ddependp r i m a r i l yo n they i e l d ofthed e v i c e(Wink i l o t o n s )and,toam u c hl e s s e rextent,on t h en a t u r eo ft herocksequence,asfollows:

Z = (^ W 3 1 5 )wh e r e Cd,th el i t h o l o g i cdept hc ons ta nt,isc i te du s u a l l yb e t w e e n108a nd1 45a n d m i g h t s a f e l y b e a v e r a g e d as120( U .S .A t o m i cE n e r g yCommission,1969b).n a r b i t r a r y"Safe" m i n i m u m de p thf o r r e s e r v o i rrockshasb e e n c i t e d b yA t k i n s o n an dJo h a n s e n(1964) as300m e t e r s(1,000 feet).onve r s e l y ,Ifthed e v i c eisemplacedat to og r e a t adepth,thel i t h o s t a t i cpressureist h o u g h t b y some tob e c o m es u f f i c i e n ttoclosea l lf r a c t u r e s-atleast,w i t h t hepassage o ft i m e-andthusdiminish a n y o r i g i n a lincreaseinthe p e r m e a b i l i ty .n a r b i t r a r y maxi-m u m d e p t h f o rr e s e r v o i r ro c ksha sb e e n c i t e d b yA t k i n s o na ndJo h a n s e n(1964) as a b o u t 2,500m e te r s(8,000feet).i g u r e 12g r a p h i c a l l yin-dicatest hatG a s b u g g y andDragon T r a i ls p e c i f i c a ti onsfallw i t h i nt hesuggestedl i m i ts ,b u t t hereserv oirsf o r Rulison,Wagon Wheel,a n dWASP a r em o s t l y deeper.H eating

T h e e n e r g yreleased b ya n u n d e r g r o u n d n u c l e a re x p l o s i o n isgenerally e q u i v a l e n tto4.185x10^-9 e r g so r 10^calories p e r k i l o-ton(Heckman,1964).hea c t u a la m o u n tofenergyl o c a l l yd e p o s i t e dasresidual t h e r m a le ne r g y depends u p o n t h ede g r e e ofc onta i nm e nt;ifcomplete,as w o u l d b ee x p e c ta b l efo rh y d r o c a r b o n - s t i m u l a t i o n p r oj e c ts ,90 to9 5p e r c e n tof then u c l e a re n e r g yisdeposited.nF i g u r e 13,

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t h ep erc en t a ge oft het ot a ln uc l ea r e ne r g ya v a i l a b l easresidualh e a t(dashedlines)Iss h o w n a s a f u nc ti on o ft hem i n i m u m tempera-tu r erisep r odu c e dInthef i r s t 100 m i l l i s e c ondsf o l l o w i n g explosionsIn tu f f and salt.sthem o l t e nrock p u ddl e sa n d c ool so n thef l ooro ft he cavity,theth e r m a l e n e r g y Is di s s i p a te db y c o n d u c t i o nth r ou g hu n d e r l y i n grockf r a c tu r e sor ove r l y i ng c h i m ne yr u b b l e ,gasc onve c ti onIn the chimney,and,a f t e r s ev era lmonths,p o s s i b l yb y liquidconvec-t i o n in thechimney.he r e s u l t a n tl ow e r i ngo ft em p era t ure producesaseriesofnewd is t rib ut io n curves(solid l in es)in d ic a t in g thatkto6m o n t h s a f te ra ne x p l o s i o n the m a x imumo b s e r v e d te m p e r a tu r efo rc o n t a in edshotsisg e n e r a l l yb e t w e e n 80 and 90oC,a n dth a tabnormaltemperatures ,d ec rea s in gou t w a r dtoa b ou t 20to300C,s ti l l extendb e-l o w theshotp o in t tode p th so f 1 .2to2.0 R ci n g r a nodl or l te ,and2.7R cin salt(Heckman,196^).n a p p r ox i m a ti on f o r th e radial ex-te nt ofsignificant res id ua lte m p e r a tu r eInr e s e r v o i rr oc k smight be:

H t =2Rc 16)A n a p p rec ia b l ea m ou nto f res id ua lthermale n e r g y e x i s tsi n a l a r g ev o l u m e ofm a te r i a le x h i b i t i n gv e r y l o w te m p e r a tu r eincreases ,suchasattheR a i ni e rsite,w h e r esome50p e r c e ntof t h e e n e r g y releasew asd ep o s it ed wi th i n m a t e r i a l o n l y k0Cb o vea m b i e n t temperatures.T hepers is t en c e ofs u c h l o w t em p era t ureincreasess h o ul d v a r ydi r e c tl yw it h yiel d and in v ers el yw i t h a n y p r odu c ti on rates,a n dinm os tcasesw i t h o u t p r o d u c t i o n ,s h ou l dr e m a i n f o r anu m b e r o fy e a r s(Tellerandothers,1968).owever,A t k i n s o n a n d Johansen(1964) em p h a s izethatthel o n g-t erm averaget em p era t urerisew i th i n the" r a di u soffracture"w o u l d b elessthan 10C,a n dw i t h i n the"crushedzone"w o u l d b eonl ya b o u t 50C.i g u r eIk, a d a p t ed f r o mth e i r data.I ndi c a te sthe estimatedin c rea s ein u l ti m a te r e c o v e r yas a f u nc ti on ofo i lv i s c o s i t yandthea v era gete m p e r a tu r eIncreasein b o t h w a te r - dr i vea n ds ol u ti on- g a sdr i vereservoirs.nb o t h types,the g e ne r a lte m p e r a tu r eI nc r e a s e ofonl yafew d egreesw ou l dno ti nc r e a s erec o v ery significantly;thea rea ofs u s ta i ne dh i g h e rincreaseisv e r y local,and,a l t h o u g h h i g h vi s c os i tyoils w o u l dbecome m o r em o b i l e w i t h i nthatarea,a n y p r o d u c t i o nwouldl e a dtoa n inevitabled ec rea s eintue temperature a n d a c ons e q u e ntre-tu r ntohigher v is c o s it y andl o w e rrecovery.NOTE,a d d e dMa y1971.

A sindicated above,t h eo ret ic a l c ons i de r a ti onsar e gen era l l ys up p o rt ed b y thel i m i te d em p iric a l da t a f r om u n d e r g r o u n dnuclear-exploslcrsitesinfo rec a s t in g o n l ys m a l l a n dlocalized th e r m a leffects.owever,the f o l l o w i n gm e a s u r e m e ntsa tt h eR ul l s o n site(Hamburger,A p ril1971^p e r s o n a l c om m u ni c a ti on)d on o tf itintothep r e d i c t e dp a tte r n:hep r e - s h o tdow n- h ol ea m b i e n tt em p era t ure was 101oC,b u tthep os t- s h otd o w n -h o l etemperature rec o rd ed d u r i n gg a s - f l a r i ngp r o d u c t i o ntestsinthes p rin g of1971a v era ged a b o u t2000C and r e a c h e da m a x i m u m of

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2230C.her e a s o n fort hesea n o m a l o u s l y hight emperaturesm o r ethanIm o n t h sa f t e r detonationofthen u c l e a rcharge a reno t c l e a r atth i stime,b u tthe b e n e f i c i a lef f ec t o fheating onp e t r o l e u mproduc-t ion m a y b egreatert hanp r e v i o u s l y thought.

R a d i o a c t i v i t yA n y nuc l ea r explosionp r o d u c e sa s i g ni f i c a nt a m o u n tofradio-

a c t i v e de b r i s ,i nc l u di ngf i s s i o n f r a g m e nts ,fusion product s ,andradio-a c t i v i t yinducedin other ma teria l sb y neutron a c ti va ti on. puref i s s i o nex p l os ion producesa b o u t 1.46 x 1023f i s s i onso r 2.9 x 1023f i s s i o nf r a g m e n t sp er k i l o t o nofe n e r g y(Miskel,1964).heseproduct sartd i s t r i b u t e din massa c c o r d i n g t o t he yield c u r ves h o w nin Figure 1 5 ;theg e n e r a ls h a p e of the c u r v eist hesamefor u235,U238,a nd ru239.The f r a g m e n t sareneutronrich,a n d ea c h s u c c e s s i veb e t a d e c a y p r oc e s s(witho r w i t h o u t gamma r a di a ti on) ,a v e r a g i n g threeinnu m b e r ,increasesthen u c l e a rcharge one unit,t h e r e b y c h a n g i n g itsc h e m i c a lspecies,un-til,a f t e ra predict a blet imes equ e nc e ,thefragmentb e c o m e sstable.Thee x c e s sneutronsn af i s s i o n e x p l os i on,a b ou t 1or2x 1023 p erk i l oton,interact w i t h o t h e r m a teria l sandinducer a d i o a c t i v especies,m a i n l y b y n e u t r o ncapture,w h i c hb e t ad e c a y(witho r w i t h o u t g a m m ar a d i a t i o n )d i r e c t l y tost a blei s otop e s . puref u s i o n e x p l o s i o nw ouldp r o d u c eno f i s s i o n products,b u te a c h k i l o t o nofe n e r g y p r o d u c e sa b ou t1023 a t o m softritium,b e t a - e m i t t e r sc r e a t i n ga p p r o x i m a t e l y 10^curiesradioactivit y,and1.5 x 102^ e x c e s sne u tr ons ,ora b o u t 10ti m e sasm a n yasp r o d u c e dinthe f is s ion process.

F o l l o w i n g a cont ainedn u c l 3 a rexplosion,allr a d i o a c t i v enucleiw h i c h a ren o t g a s e ou s att het e m p e r a t u r e ofm o l t e n r o c k(1,500to2,000oC )areentrainedint he m e l ta n dbecome apartoft he a l m o s tc o m p l e t e l yinsolubleglass p u d d l eat t heb o t t o m ofth ec a vi ty .Prompt"v e n t i n g of gasest hroughg r o u n df is s ures hasoccurredin o n l y3 of themoret h e m 200underground t e s t sf i r e d f r o mI96I toI969in s t e m m e dv e r t i c a l h o l e s( U .S .A t o m i cE n e r g y Com m i s s i on,1969a);in t h o s e cases,enough r a d i o a c t i v i t ywasr e l e a s e dtob edetectedo u t s i d e oft hecon-t rolled area.ntheo t her tests,itise x p e c te d t hatm o s t of the re-m a i n i n gg a s e o u snu c l i de sp l a t eo uto n the c ool rubbleasitfallst h r o u g ht hegas duringthep r o c e s so fc h i m n e y formai;ion. f e w nuclei,es p ec ia l l y t henob l e gases,a r eg a s e o u s a t nor m a lt e m p e r a t u r e sorde-v e l o pb y d e c a y of nor m a l gases.l l v o l a t i l enuclidesa re d i f f u s e di nto t hev oidsor f r a c tu r e sc r e a t e db y the explosions.hee f f e c t se v a l u a t i o nr e p o r tf or R u l i s o n( U .S .At omicEnergy C ommission ,1969c)suggest st h a t thed i s t r i b u t i o no f garama-emlttingr a d i o n u c l l d e sin-j e c t e dint ot hes u r r ou ndi ngc r a c k sa b o v e a ndb e l o w thes h o tp o i n tw o u l dav erage:

1 3


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Hg =2.2 R c 17)an d Dg =1.5R c 18)A f i r s ta p p r ox i m a ti on o fv o l u m ea f f e c ts d m i g h t b er e a c h e d b y assuming:

Rg = 2R c 19)andth e nVg =0.033 Rc 20)

ifvol u m ei sexpressedin th ou s a ndsofcubic m e te r s .e l a y e d ve nti ngo f a v e r y smallf r a c t i o n of t h e r a di oa c ti vi ty m i g h t o c c u rb y s eep a getoth es urf a c e a f te rc a v i t y c o l l a p s e;thisa p p e a r st oh a v eh a p p en edins o mes ev enofthe l o w - y i e l du n d e r g r o u n de x p l os i onsf r o m 1961 to1969( U .S .A t o micEnergy C om m i s s i on,1969b),i n c l u d i n gon ecaseincarbon-ater oc k w h ereu n u s u a l l yh i g hp r e s s u r e w as b u i l t up b y thec r e a ti on ofc o n s i d e r a b l eCO^in t hec him n ey.oi nte r m e di a te -o rh i g h - y i e l dev en t sh a vevented,and e n o u g h e x p e r i e nc ehasb e e ng a i n e dt oc or r e c t ea rl ierdeficiencies.

H he n a t ureofther a d i o n u c l i d e sp r odu c e d b y a n u c l e a r ex p l o s io nva r i e s w i t hthety p e o fe x p l o s i v ed ev ic eandt h e c h e m i c a l n a t ure ofthespecifics u r r ou ndi ng rock.nah y p oth e ti c a l P l o w s h a r e ex p l o s io nw i t h a y ie l dof o n em e g a ton,a s s u m e d tob e 1 p e r c e n tf i s s i o nand99p e r c e n t fusion,in a v e r a g e c r u s t a lm a te r i a lw i t h a s a tu r a te d p o r o s i t yof20percent,thep r o d u c t sw o u l d v a r yinc u r i ea c t i v i t y w i t h time ass h o w nin Figure16(afterStead,?S6h). The f i s s i o n p r o d u c t s d ec rea s er a p i d l yb ythreeor de r sof m a g n i t u d einthe f i r s t week,and fiveor de r sof m a g ni tu dein the f i r s tyearand,a tth ee n d ofoneyear,o n l y S r-^ andCsl37a r eim p o rt a n t .hef u s i on p ro d uc t ,tr i ti u mo rH3,isthem os ta b u n d a n tn u c l i d e(by 2o rd ers o f m a g n i t u d e ) afteroneyear,a n d w o u l dr e m a i n i m p o r t a n t f o r m or e th a n on ec en t ury.nducedr a d i o a c t i v i t y i sr e l a t i v e l ys h or tl i ve dinthe c o m m o n m e t a l s( A l ,Mn ,Na,a n dFe),and de c r e a s e sr a p i d l yb y fouro r d e r sofm a g ni tu deint he f i r s tw e e kand,a t th ee n dofoneyear,o n l y C o^ Oisaignificant.A l t h o u g hC l^i sl o n g-l iv ed ,thea m ou ntp r odu c e disin s ign ific a n t ,eveninah y dr oc a r b on- r i c h reservoir,as c l * -i sc r e a t e d b y a c t i v a t i o nofn i t r o g e n a ndnotcarbon.na c onta i ne dn u c l e a rex p l o s io n ,o n l y thel o n g - l i v e dra d io n uc l id es ,p a r t i c u l a r l y thosew i t h h a l f - l i ve sof con-s i d e r a b l y m o ret h a nf i v eyea rs ,a r eim p o rt a n tine v a l u a t i n g thepost-e x p l o s i o nreen t rya n d e x p l o i t a t i o no fp e t r o l e u mr e s e r voi r so rthep o t e n t i a l c onta m i na ti on o f a s s o c i a t e dgro un dwa te r s .a l c u l a ti onsofr a d i o a c t i v i t y f o rd i f f e r e n t e x a m p l e sareg i ve nin T a b l e5 .ignificantr e d u c t i o ninthe a m o u n t ofr a di oa c ti vi ty(Lessler,1970)c a n res ul t b yr e d u c i n gtheyieldo ft h e f i s s i o nt rigger in the n u c l e a rdevice,b yu t i l i z i n g the l ea s t o b j e c t i o n a b l estructural m a t e r i a l sint h e device,a n db y p u t t i n g s h i e l di ngo rn e u t r o n - a b s o r b i n gm a t e r i a l sa r ou ndthed ev ic e.

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F o r ag a s - s tl m u l a tl on p r oj e c t,t he gaseousp h a s e sof H3 a ndKr8?a p p e a rt ob et heonl yi m p o r t a n tc onta m i na nts a f te r a n o r m a l de l a ytime.l g g i ns andR ode a n(1965)a nti c i p a te d thats u c h c o n t a m i n a t i o nw o u l dd e c r e a s ew it hp r o d u c t i o n a n d b en egl igib l e a f t e rr e m o v a l of6o r7v o l u m e sofgas.ni th(1970) c a l c ul a t esthat t r i t i u m a n d ky rp t o ni s otop e s m a d e u p theb a l kofth ec onta m i na ntsin theG a s b u g g ychimney(CH3T= 80^,K r 85= 1 5 5 t ,C 1 a n d A r 39insmallamounts),a n d onl y7p e r c e n t of t he original c o n c e n t r a t i o n lemained a f t e rr e m o v a lo f2^h i m n e yv o l umes ofgas.n th e R u l i s on shot,a b o r o n c a r b i d e shielda r o u n dt hef i s s i on d ev ic ed e c r e a s e d t hetritium b y a f a c t o r of3 or^(Frank a n d others ,1970).e c o n t a m i n a t i o nofp r o d u c e dgasisb e i nge x p l o r e d b y s p ec ia lp r o c e s s i n g te c h niqu e s(Wethington,1970),s uc hasw a s h i n g th e gaswi th w a t e rtor e m ove H 3and w i t hl iq u i d n i t r o g e n tor e m o v e Kr85.owever,e c onom i cu ti l iz a ti on of t her e s o u r c e a p p ea rsm o s t p r a c t i c a b l e b ya c a r e f u l l y c ontr ol l e d di l u ti ona n dd i s t r i b u t i o ns y s t e m(Jacobs an dothers,1970)^orb y thes hip men to fth e gastoa r e -m o t e p o w e r p l a n tf orc o n v e r s i o n toane w e ne r g yf o r mw i t h c ontr ol l e db u r n i n g techniques.

F o r a n oi l - s ti m u l a ti on p r oj e c t,the ra d io a c t iv eg a s e s m a y b eofl o w e r c o n c en t ra t io n ,b ut thet r i t i u m de ve l op e d f r o m a s s o c i a t e d wa te rm a y b es i g ni f i c a ntl y greater.heove r a l l effect ofe x p o s u r eto gammar a d i a t i o n oftheoils a m p l esa tth eGn o meP ro j ec t w asl e s st h a n theove r a l le f f e c t ofex p o s ure t oshock.amplee x p os u r eto7x10^r o e n t g e n sg a m m a radiati m i n c r e a s e d t hep ol y m e r iz a ti onino n eo ilandp a r t i a l l y c r a c k e d another;t h e e f f e c t was lessint hea r o m a t i coilsth a nin thep a r a f f i noils.sex p ec t ed ,therewasnor e s i d u a lradio-a c t i v i t y int hesamples.he p o s s i b l e c o n t a min a t io n o f a s s o c i a t e dgasorw a t e r w o u l d a l s ode c r e a s e w i t hp ro d uc t io n ,andd e c o n t a m i n a t i o n b ys p e c i a l p r o c e s s i n g t ec h n iq uesisa l s ofeasible.

F o r a n yp e t r o l e u m - s t i m u l a t i o nproject,c o n t a m i n a t i o n oft he gro un dw a t e risa potential,hazard,a sthe b i ol og i c a l l y s i g n i f i c a n tradio-n u c l l d e sa te x p l os i onsitesa r ea t orafew orderso f m a g n i t u d e greaterth a n t hem a x i m u m p e r m i s s i b l ec o n c e n t r a t i o n ind r i n k i n gw a t e r( s ^ . eT a b l e5 ) .t ea d ' s(1964)s u m m a r y of al lem p iric a ld a t ai ndi c a te s negli-g i b l et r e m s p o r tof r a di onu c l i de sf r o m a n y p a s tn u c l e a r t e s tsite,b utheemphasizest h a tthe s it es w e r e c a r e f u l l yselected t o m i n i m iz e thep o s s i b i l i t y of wi de s p r e a dd i s t r i b u t i o n ofnuclides b y g r o u n d - w a t e rtr a ns p or t.ts uc he x p l os i onsites ,p os t- e x p l os i on g r o u n d - w a t e rmove-m e n ta p p e a r stob e towardst h ea r e a o f chimney c o l l a p s e ,a n ditm a yta k ec o n s i d e r a b l etimet ol e s t o r ethep r e - e x p l os i onw a t e r - t a b l ec o n d i t i o n so n erub b l ec h i m n e y u n d e rob s e r va ti on d i d n o tf i l l wi thw a t e ru n t i l m o r e thant h ree y e a r sa f t e r the shot.hea v e r a g e v el o c it ya ndd i r e c t i o n of f l ow c a n b ee s t a b l i s h e df r omf i e l do b s e r v a t i o n s ,al-t h o u g hl o c a l l y m a x i m u mv e l o c i t i e ss e ve r a l - f ol dl a r g e rt h a nt heaverageas w e l l asa nom a l ou s d i s p e r s i o np h e n o m e n a dooc c u ra n d m a yn o t be de-l i ne a te d.f t e rres t o ra t io n o fthe w a t e r table,r a d i o n u c l i d e s will bet r a n s p o r t e d d o w nthe r e g i ona lh y dr a u l i cgradient.at a a c c u m u l a te d

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f r o m c u r r e ntr a di oa c ti vew a s t e disposal e x p e r i e nc e si ndi c a te th a tm o s tf i s s i onproduct so rneutron-activ at ed nu c l i de s p a r t i c i p a t ein ion-exchanger e a c ti ons w i t hther oc k matrixin suchaw a y thattheionswi l lm ove atsignificant ly l o w e r ratest h a n t heground-w at er flow.nm os t cases,thisi so n l y a f ewp e r c e n t oraf r a c t i o no f apercent ofthe nor m a lrate.hese d a t aalsos h ow th a tthec onc e ntr a ti ons w i l lh edi l u te d asther e p e ti ti veionica d s o r p t i o nc y c l eanddiffusion di s tr i b -ut ether a d i o a c t i v i t yo v e ra p r o g r e s s i v e l ylargerarea.ritium,how-ever,m a y no tb esoretarded;this,c ou p l e d w i t hitsd o m i n a n c e a nd l o n glife,m a k e sit th em os ti m p or ta nt o fall nu c l i de sasa p o t e n t i a lhazarding r ou ndwater.oa v o i d thetr i ti u m con t aminationin e i th e rthew a t e ro rh y d r o c a r b o nd ep o s it s ,N o r d y k e(l970)suggeststh eu se o f a l l - f i s s i o nnu c l e a re x p l os i ve sin p e t r o l e u m - s t i m u l a t i o nprojects.

Thus,b e c a u s eo f s l oww a t e rm ove m e nt,r a di onu c l i de adsorptioncharacteristics,andu s u a l l y shortd e c a y rates,th e r e has b e e n n or a di ol og i c a lcon t amination p r ob l e m sofground-w at er we l l sw i t h i n e ve naf ewkilometerso fp a s t te s tl o c a t i o n s(Tellerand others,1968),b u te a c h f u tu r esite w i l lrequire f u l linvestigation andu n d e r s t a n d i n go fthe geologica nd h y dr ol og i cc ondi ti onsso astob e a b l etop r e d i c tw herea ndw h e n p o s s i b l y hazardousc o n c e n t r a t i o n sofr a di onu c l i de sc a noccur.A sa c a s einp o in t :new e l ldrilled j u s t ou ts i de o f ar u b b l e c h i m n e yto an aquifer lessth a n 100etersb e l o w thes h ot p o i n te x h i b i te dn oc o n t a m i n a t i o nf i veyears a f t e r the event.tisf u r t h e r b e l i e v e d that,w i t h c a r e f u l planning,a n yr a di onu c l i de sthat are detected c anb e com-p l e t e l y r e m ove db ycurrent ly e nvi s i one d d e c o n t a m i n a t i o np r oc e s s e s(Wethington,1970).S e i s m i c i ty

L i ttl eof th e g r e a t energy r e l e a s e db y an underground n u c l e a r ex-p l o s i o ni scon v ertedtoseismicenergy.i c k e y(1964)citesthel a tte raso n l y 0.015to2.0percent o f the tota lf or e x p l os i vey i e l dsr a ng i ng f r o m0.43 to200 kil o t o n s;R o d e a n(1970)c i te s a r a ng e f r o m0.01to 1p e r c e n tdepending u p o n the p r op e r ti e soft hes u r r ou ndi ngmedia.tte l e s e i s m i cd is t a n c e ,Romney(1959)r e l a te sm a g n i t u d e(Mo ntheWo o d - A n d e r s o n tor s i ona ls e i s m og r a p h)toy i e l d(W)as f o l l o w s:

M=3-64 +log10W 21)U s i ng thisequationand calculating t h ee ne r g yreceived as a p e r c e nt-a ge of th e t o t a l e ne r g y rel ea s ed ,expect a ble va l u e sa p p r ox i m a te 0.3^^for10kt,1.67^ f or100 kt,and6.67^ for1megaton.owever,th ep e r c e nta g e sc a l c u l a t e dforact ual e ve ntsarea na m ol ou s asi ndi c a te db y 0.14^ f or11 k ta n d 0.08^ for 100 kt,b o t hinalluvium;0.20^ fo r2.4k tand0.25^f or200 kt,b o t hin tuff;and 0.24^ for0.43k tinbasalt.enerally,al a r g e rfraction o fseismicenergy,p a r t i c u l a r l ythe higherfrequencies,w i l l b e t ransmit tedinth estronger,m or ecom-petent,and less porous media,b utr o s tm e d i ab e h a vequitesimilarly

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un d er the w a t ertable.v en s uc h v ery small p erc en t a geso f thet ot a l e x p l os i ve e ne r g i e sa res uf fic ien t togen era t es t r o n gseismicpulsesw h i c hcreatesevereg r ou nd m o t io n w it h in ana rea n ea rtheex-plosion.he t ot a l e u n o u n to f en ergy a rriv in g ata n y one l o c a t io n isd ep en d en t m o s t l y on they i e l do f the explosion,theg e ol og i cenviron-men t of thetravelpath,a n d thedi s ta nc e f r o mthes h ot point.heh i g hfreq uen c ye ne r g y g e n e r a l l y is grea t l yr e du c e d w i t h i n severalth ou s a ndmetersof thes h ot p o i n tasthes h oc ken ergy istr a ns f e r r e dtothegeologicenvironment,w h i l el o w freq uen c y en ergy a t t en ua t esv e r ys l o w l yan d m a /b ef e l t a t m u c h g r e a t e r distances.heseismice ne r g yrec eiv ed ata n y one p o i n tc a nb ec h a r a c te r iz e d b y thef r e q u e n c yofg r ou ndm o t i o n(f incycles p e r s e c ond) andth r e etypesofa m p l i tu deofg r ou ndmotion:a rt ic l ed i s p l a c e m e n t( d ) ,p a rt ic l ev e l o c i t y(v=2 t r fd),a n dp a rt ic l e a c c el era t io n(a=2fv .hesep a ra met ersc a n b e p rea ic t edc o n s erv a t iv el y b y equ a ti ons d e v e l o p e df r o m thee x te ns i vee m p i r i c a ld a t ac ol l e c te datthe Nev a d aTestSite.s s u m i n gt h a ttheshotp o i n t occursinh a r d rock,asina p et ro l eum-s t imul a t io n project,thep r e d i c t e dp e a ksurfacem o t io n willv a r yw i t h y i e l d(Win kt),s l a n td i s t a n c e(R in r a ) ,a n ds ta ti on e nvi r onm e nt asf ol l ow s(Kinnamona n dotherd,1967):

S t a t io n Vel o c it y orv = A c c e l e r a t i o n o r a =Onhardr oc k 8.64x 106^-73R"1-8? 5.03x 105W0'7R-2-0022&23)Ona l l u v i u m 2.94 x 10? W0R -l.8 7 1.06 x 106W0'7R-2.002k & 25)Ther e d i c t e dvaluesf o r v e l o c i t yanda c c el era t io n a r e p l o t t e dinFigure 17f o ryieldso f10,5 0 ,a n d100kilotons.he d a m a ge c r i te r i af o r suchg r ou nd m oti onsisb a s e do n m u c h lessem p iric a ld a t a w h ic hiso f t enc onf u s e db yf a l l i n gtot a k eintoa c c ou nt v ery l o c a lc ondi ti onsw h i c h c a n c ontr i b u te t ospecificdamage,such as p r e - e x i s t i n gstruc-turals tr e s s e sres ul t in gf r o msettling,etc.o r m o s tI n d us t ria lappli-cations,as a f e ty f a c t o r of 2 o rm o ref o rthep r e d i c t e d di s ta nc e si sc o n s id ereda d v i s a b l e.nthe v e l o c i t y plot,the t ra d it io n a l b r e a k s f o rthe em p iric a l l y de r i ve dd a m a gelevels,p a rt ic ul a rl y the U ,S .B u r e a uofMinesfindings ,arei ndi c a te d asd eriv ed f ro m Mic key(1964) a n dothers.Onthea c c el era t io n plot,thec l a s s ific a t io n b ythe"damagefactor"i st a k e nf r o m Hughes(1968).o n s id era b l eeffortIsex p en d ed at U .S .P l o w s h a re p ro j ec t sto a v o idseismicdamage,p r i n c i p a l l yb y c h o o s i n gasr e m otea n dun p o p ul a t ed s i te s aspracticable.a reful m o n i t o r i n go fg r ou nd m o t i o ni sc ondu c te d d u r i n gea c htest.t Gasbuggy,itwaspre-di c te dthattherem i g h tb ega s -w el l d a m a ge w i t h i na b o ut400met ers ofa 10-ktshot ora b ou t1,200met ersofa 100-ktshot;res id en t ia l p l a s te rc ra c kin g m i g h t o c c u ra tdi s ta nc e s u p^o2.5 kil o met ersif 10k t o r7.2kil o m et ersif 100kt,a n d p o s s i b l ytherem i g h t b es o me s e t tl e m e ntp ro b l em sa tgrea t er distances.hea c tu a lshot yiel d w as29k tw h i c hd a m a gedo n e e x i s ti ngw e l l133 met ers f r o m thes h ot p o i n tb u t causedn oda m a g etoa n o t h erw e l la tad is t a n c eof 8 00meters.hus,ground

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m oti onsa ndt hep o s s i b i l i t yofda m a g e tostructures c a n n o w b e fa irl ya c c u r a te l y p r e di c te d( U .S .A t om i cE ne r g y Commission,1969a).

U nde r g r ou nd n uc l ea r e x p l os i onse x p e c ta b l y create s u b s e q u e nt( j e l s m i cactivity.ow - y i e l deventsaref ol l ow e d b y t r e m o r s m o s t l ya s s oc i a te d w i t hc a v it y collapsean dc h i m n e ygrowth.i g h - y i e l d events,; s u c h asth em e g a ton B e nh a m e x p l os i onof1 9 De c e m b e r 1968,c a n causesomem i n o rdi s p l a c e m e nta l ongp r e e x i s t i n gfaults w i th i n 10 k i l om e te r softhes i t eand g e ne r a te somea f te r s h oc k sw i t h i n12k i l o m e t e r s ,al lo fwhichareofm u c hs m a l l e ra m p l i tu deth a n th os er e s u l ti ngf r o m th enu c l e a revent.ode a n(1970)statesthats e i s m i cenergiestr a ns m i t te db y chim-n e y c ol l a p s ea n d a f te r s h oc k sar ea tl e a s t a n or de r ofm a g n i t u d e w e a k e rthanthosed irec t l y p r odu c e db y a n explosion.u r r e nt e vi de nc eindicatesthatp r op os e d y i e l dsatP l ow s h a r e tests,s i m i l a rtoth os ea nti c i p a te d a tNTS,w i l ln ottr i g g e r deunagingearthquakeso ra f te r s h oc k s(u.S .A t om i cE ne r g y Co m m i s s i o n ,1969a).E c onom i c s

Thee c o n o m i cf a c t or ss u r r ou ndi ng the e nti r e e x p e r i m e nta l p r o g r a mm a yh a ve ade c i s i veinfluenceinul t im a t el y l i m i ti ngorc ontr ol l i ngthea p p l i c a ti onofe x p l os i onstop e tr ol e u m - s ti m u l a ti on p r o j e c t s .F i g u r e1 8i n d i c a t e sth erelative p l a n n i n g c os t s w h i c ha reb a s e d onth e r m onu c l e a rexplosivesr a ng i ngf r o m $350^000f o r a1 0- k t d e v r l c eto$600,000f or a2-mtde vi c et h e s earechargesw h i c h have b e e nreleasedb y theA E C f o r them a t e r i a l s ,f a b r i c a t i o n ,arming,and f i r i n g of ath e r m onu c l e a r de vi c ef o r f e a s i b i l i ty s t u d i e sandevaluations.hisisoneof thel a r g e s titemsin a n y p r o j e c tbudget,a nd m u s tbe r e du c e d b e-forea n y p e tr ol e u m - s ti m u l a ti on testb e c om e seconomical.o tI nc l u de db u talsoof s i g ni f i c a nc eare the c o s t s f o rf e a s i b i l i t ya n a l y s i s ,ex-p l o r a t o r ywork ,sitepreparation,tr a ns p or ta ti on ande m p l a c e m e nto f de-vice,a nds u p p or t functions.ie e m p l a c e m e nt h ol eIsa n o t h e rm a j o rhurdlesince costsIncreasee x p ote ntl a l l y w i t h holedi a m e te r and depth;H i l l(1970)indicatesthata t d ep t h o fm o re than 2,300 meters,hole-r e l a t e d c o s t sn o rm a l l y c ons ti tu tem or e th a n 50p e r c e nt ofthe t ot a lcost.

A t k i n s o n andJ oha n s en(1964)suggestedth a ta$0.5mil l io ns ti m u l a ti on- p r o j e c ti nve s tm e ntw o u l drequirethede ve l op m e nto fa ne x tr a0.5m i l l i o nb a r r e l s ofoiltop a y f o r i t ,w h i c h issuch as i g ni f i c a nti n c r e a s einp r o d u c t i v i t yastob eg e ne r a l l yunlikely.H c T . z e r(1970)e s ti m a te sthat the t ot a l gasinp l a c einthel60 acresa t theGa s b uggy siteis o n l y w o rt h a b ou t1m i l l i o ndollars.p to1970,a b ou t$50,000 w o r t h ofgashad b e e n extracted.a b l eoshows a ne s ti m a te dt ot a lc os t o f5.9m i l l i on dol l a r sf o r th eR u l i s on p r o j e c tb uta l s oi n d i c a t e ss u g g e s te drealisticvalues f o r a futureshotinthesamefield.a n y s i g ni f i c a nt reductionsca nb e m a d e assomeop e r a ti onsdon ot requirer e p e ti ti on andte c h nol og i c a lde ve l op m e ntssaveexpenses.

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NOTE:d d e dMa y I97I.F r o mt heR u l i s on ex p erien c e ,We r t ha n do t h ers(l97l) h a vees t im a t edthetota l c o s tof3or4 100-ktnu c l e a rc h a rgesd e t o n a t e dinasinglewe l lin theGreen R i v e rb a s i n tob eo nthe or de r of2.5m i l l i o ndollars,i ndi c a ti ngth a tc om m e r c i a l g a s - s t i m u l a t i o np r o j e c t s a re be-c om i ngfeasible w i t h thec u r r e nts t a t e-o f -t he-a rt .

P ub l ico p i n i o nA m a j o r de te r r e nttoth ed e v e l o p m e n tof a m or era p idti m e ta b l e

f o rc o n d u c t i n gPl ows h a r e e x p e r i m e nts hasb e e nt h ea d v e r s e c r i ti c i s mg e ne r a te dna ti ona l l y a n dlocally.a t kin s(1970)s t a t est h a t m u c h ofthe o p p o s i t i o ncomesf r o mchose w h o a re notf u l l ya wa r eofn uc l ea r-e x p l os i on p h e n o m e n o l o g y -n ol e g a l c a s ef o ro p p o s i t i o n h asb e e n sub-s ta nti a te d-anda rguesth a ti m p r ove dp ub l icr e l a ti onsa rerequiredtob e t t e r i nf or m theg e ne r a l p u b l i ca b ou ttherealf a c tsc onc e r ni ng nu c l e a rd et o n a t io n s ,p a r ti c u l a r l y th os ea s s oc i a te dw i t hd e v e l o p i n ge ne r g yre-sources.

U.S.S.R.E T R O L E UM- I N T E N S I F I CA T I O N P R O J E C T SA l t h o u g htheS o v iet sh a v ea n ex t en s iv enu c l e a rt e s t i n gprogram,

th e i rp u b l i s h e dte c h ni c a l c onc l u s i ons a reb a s e d a l m o s tw h o l l y o np u b l i s h e d U n it edStatese x p l o s i o nexperience,and,p red ic t a b l y ,thereisl i ttl edi s a g r e e m e nta b o u t p h y s i c a l p r i nc i p l e so reffects.heS o v iet sd otheorize(U.S.S.R.A c a d e m yo fSciences,I969)th a tthesizeo fthe nu c l e a r e x p l os i on c a v i t y is m or e c l os e l y r e l a te dtothe crush-ings t r e n g t hofthes u r r o u n d i n g r oc k t h a n to t he l i th os ta ti cpressure,a n d th a t them a x i m u mc a v i t y v o l u m erea c heddu r i ng t h ee x p l os i on s eq uen c eex c eed st h ef i na lvol u m e(theyc a l c u l a te b y1.5 a n d2t imesr e s p e c ti ve l yf o rtheGn o me andS a l m onex p l o s io n s).uc hth e or e ti c a l di f f e r e nc e sh a v el i ttl es i g ni f i c a nc einr e g a r d t othep h y s i c a l e f f e c tst h a t needtob ec ons i de r e dinp e t r o l e u m - s t i m u l a t i o np ro j ec t s.

TheS o v ietp h i l os op h i cp o s i t i o n a n d te c h ni c a lc r i t e r i aa p p l i c a b l etothe"in t en s ific a t io n "o fp e t r o l e u m p r o d u c t i o nw e r er a th e r f u l l ys t a t edb y K e d r o v s k i y an dM a n g u s h e v inI967a n da m p l i f i e d byMa ng u s h e va n dZ ol otovi ts k a y ain1969.heS o v iet sstresst h a ts in c eonl y 35to^5p e r c e n tof e x i s ti ngp e t r o l e u m r e s ou r c e sa r e r e c o v e r e df r o m reser-voirs ,a ndb e c a u s ec u r r e nte x tr a c ti on t ec h n iq uesa r et i m e - c o n s u m i n gan dcostly,ucleare x p l os i onsca n s u b s ta nti a l l yi nc r e a s ean ds u s ta i ntheyield,de c r e a s e the e x p l o i t a t i o ntime,a n du l t i m a t e l yl e a v e lesspetro-l e u min th erock.heS ovi e ts c l a i mc ons i de r a b l e t h e o r e t i c a la n dsomee x p e r i m e nta li nve s ti g a ti onan dmo d el in g ,in c l ud in gb o t h chemical a n dnu c l e a r e x p l os i onsa t b o t hp r o v i n ggro un d s a n di ndu s tr i a lsites;test

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en v iro n men t s h a ve e vi de ntl y I n c l ud ed granite,shale,limestone,clay,salt,a nds a nds t one ,andshotp o i n t sh a v eb e e nb u r l e das d eep as1,500 meters.e dr ovs k l y(1970)c l e a r l y emphasizesthatthe p os i ti veresultsatone m a j or mul t ip l enu c l e a r - e x p l os i on siteIna n experi-men t a l oi l f i e l dh a v e en c o ura ged t h e m top r op os ea tl e a s tt w ooth e rl a rge-s c a l e a p p l i e dprojects ,S c hemeI a ndSchemeI I ,a ll ofwh i c hareim p res s iv eint h eir magnitude. Inc u r r e ntl y commercial ,m o d era t e-l yp e r m e a b l e c a r b o n a t eres erv o irsc o n t a i n i n gn a t ura lga s o rw a t er-d riv en oil,theSovietsp ro d uc e a fra c t urep a tte r n b y nu c l e a r ex p l o s io n swi th i nthe d e p o s i torb e l o w thep e tr ol e u m - wa te r interface,a n dth e r e b ycreateg r e a t e r p e r m e a b i l i ty andw a t e r pressure.hestated o b j e c t i v ei sfaster,a n dth u sm or e economic ,e x p l oi ta ti on of ac om m e r c i a lfield.Theen v iro n men t a l da ta fortheseU.S.S.R.p ro j ec t s ares um m a rizedinTable7a n d are p r e s e nte dg r a p h i c a l l yin Figures19 to2k. Thea v a il -a b l el i te r a tu r es ugges t sthef o l l o w i n gdi s c u s s i on o fthespecificeffectsofu nde r g r ou nd n uc l ea r ex p l o s io n sasrelated t op e t r o l e u m in-t en s ific a t io n p ro j ec t s.F r a c tu r i ng

TheS o v iet srec o gn izef r a c tu r i ng asthep r i m a r yp h e n o m e n a inpro -d u c t i o n in t en s ific a t io n .heydi f f e r lit t l e f r o m theA m e r i c a nsin t h eirgen era l de s c r i p ti on o fthe fra c t urezone,a n dc o m m o n l y citethe U .S .p a ra met ricv a l uesf o r R , , ,H f ,a n d Lf.owever,K e dr ovs k l yan d Ma ng u s h e v(1967)s u g g e s t t h a t th ea s y m m e tr yo f f r a c tu r i ng aro un das h a l l ow s h o tp o in tw o u l db e less m a rked atg r e a t e rd ep t h sand t h a tI n d iv id ua lfra c -turesm a y ex t en db e y ond p red ic t ed distances.a ng u s h e vn dZ o l o t o v l t s ka y a(1969) andK e d r o v s k l y(1970)t a l k of ra d ia lfra c t urezones a t d ep t h so fa b o u t1,500 m e te r sw i t h p a ra met ers asin d ic a t edinTable 8 .he onec o m p l et edtesta ttheex p erimen t a l o il fiel d w i t h t w o2.3 k t ex p l o s io n sa tad ep t h of1 , 3 ^ 0met ers p ro d uc ed afra c t urep a t -te r nas a l s oI n d ic a t edinTable 8.heU.S.S.R.A c a de m y o fS c ien c es(1969)s i m i l a r l y im p l ies a t h eo ret ic a ls p heric a ld i s t r i b u t i o noffra c -turese x t e n d i n g to d is t a n c esontheo r d e ro fonem a gn it ud e l a r g e r th a nthe c a v it y(R =10 1 ^ , ) .l l o ft h es e figuresrep res en ta m or e op ti -misticview ,b o t h ast oc onf i g u r a ti on a n d magnitude,th a n t ha ts up p o rt edb y p rev io usA m e r i c a n experience.

TheS o v iet se v i d e n t l yh a v eb e e n g r e a t l y I m p res s edb y thedi f f e r e nc einthe fra c t ure p a t t e r nb e t w e e n r oc ktypes,s t res s in g th a tm a x i m u m frac-turingi se x p e c t a b l einthem o s tb r i t t l erocks.a ng u s h e van dZ o l o t o v i s k a y a(1969) c o n c l ud e t h f . tth er e s e r v o i rr oc k s m o s ta m e na b l etof r a c tu r i ng arec a r b ona te s ,ac onc l u s i on w h i c ht h ey s up p o rt b yc it in g thep h y s i c a l c h a n gesrep o rt edintheex p o s edsampleso fPr oj e c tGnome.hey f u r t h e r emphasizeth a t c a r b o n a t ereservoirsa rew id e-spread,c onta i ni ng a b ou t77p e r c e nt o fthe S o v ietoild ep o s it sa n dl 8.5 p e r c e nt ofthe gasreserves(other gasreservesInclude10 p e r c e nt

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w i l ld'istroy theo i l - w a t e r i n t e r f a c ea nds om e oftheinterbeds,there-b y p r om o t i ngi n c r e a s e dw a t e rp r e s s u r eo n theoilan dsta bilized p r o -du c t i o n a t a h i g h l e v e lf o r a l m os t a n o t h e r decade(fig.2k ,

A l l o f theS o v i e t p r o j e c t sa p p e a r to b ew i t h i nc o n v e n t i o n a l l ycommercialfields w i t h m o de r a t ep e r m e a b i l i t yvaluesr a ng i ng 2o r3orderso f m a g ni t u de h i g h e r t h a nthose ofth e U .S .s itesc o n s i de r t if ors t i m u l a t i o n p r o j e c t s(seefig.8 )a g a i n p oi n t i ng upt h e i re m p h a s i so n i n t e n s i f i c a t i o no f p r o d u c t i o n ;t h a t i s ,m o r e a t a f a s t e rra te w i t h c o n c o m i t a n t o p e r a t i o n a lsavings.

Effectson r e s e r v o i r g e om e t r yTheSovietsa p p e a requally c o g n iza n tof the need t o m a t c hthe

r e s e r v oi r d i m e n s i o n sto them a g ni t u de oft he n u c l e a re x p l o s i o np h e n o m e -n a .oc o n f i n ethe e f f e c t i v e p o w e r of t heb l a s tto the r e s e r v oi rrock,Ma ng u s h e vand Z ol o t o v i t s k a y a(1969)s u g g e s tfirst p r i o r i t yr e s e r v o i r sshould havet h i c k n e s s e so f nolesst h a n 50to60m eters ,and30m e t e r sm i g h t b ec o n s i de r e dam i ni m u m th ic knes s .i ne t y - e i g h tp e r c e n tofSoviet o il reservesinc a r b o n a t e r o c k so c c u rinr e s e r v o i r se x c e e di ng30m e t e r sin th ic knes s ,and50p e r c e n tinreservoirse x c e e di ng 50m eters;50p e r c e n t of S o v i e t gasr e s e r v e s o c c u r inr e s e r v o i r s m o r et h a n30m e t e r sthick.w oof thep r o j e c ts itesh a v e reef s t r u c t u r e s kJOo500m e te r sthick,a n d thet h i r dhasa domecc a r b o n a t e r e s e r v oi rw i t h am a x i m u m t h i c k n e s se x c e e d i n g100 meters.

Them i ni m a lpermissiblec o n t a i nm e n tde p t h(i nm e t e r s )isafunc-tion ofthe c u b eroot o fyield(i n k i l o t o n s )tim es o i t h o l o g i ccon-stantw h i c hisc i t e db y K e dr o v s k i y a n d Ma ng u s h e v(1967)t ov a r y b e-t w e e n100 and 1 50(see equation 15).a ng u s h e v and Z ol o t o v i t s k a y a(1969)i n d i c a t e 500 metersas a n a r b i t r a r y safe de p t h o fb u r i a ladi m e n s i o n thato c c u r sin995 p e r c e n t ofa l l Soviet o i l de p os i t sI nc a r b o n a t ereservoirs,ande s s e n t i a l l ya l lS o v i e t gasdeposits.l lp e t r o l e u m - i n t e n s i f i c a t i o n p r o j e c t s a rec o n du c t e d at v e r y safedep th s .

Top r o t e c t a p e tr o l e u mres ourc e ,the c a p r o c km u s talso b e o fsufficient t h i c k n e s sandthede v i c ep l a c e d p r o p e r l y so that the ex-p l o s i o ndoes n o t b r e a c hthe cap.a ng u s h e v a n dZ ol o t o v i t s k a y a(1969)s u g g e s t a m i ni m u m thicknessr a ng i ngb e t w e e n 50and100 metersan d n o t othat90.9 p e r c e n to fthe l a r g e r S o v i e t o ild e p o s i t s h a v eac a p r o c k ex-c e e di ng 100m e t e r s ,an dm o s tS o v i e tgas d e p o s i t shave ac a p r o c k b e t w e e n50an d1 00m e t e r sthick.onversely,s u i t a b l ereservoirsshould n o t b eso de e pthat t e c h n i c a l ore c o n o m i c a l d i f f i c u l t i e s are e n c ou n t e r e d dur-ing t hedr i l l i ng oftherequisitel a r g e - di a m e t a rholes.a n g u s h e v a ndZ ol o t o v i t s k a y a(1969) r e c o m m e n dinthel i g h t ofc u v r e n t t e c h n o l og ythat e x p l o s i o n ss h o u l d b eatd e p t h s p r e f e r a b l yno g r e a t e r th a n2,000meters.i g h t y - e i g h t p e r c e n toftheS o v i e to ildepositsin c a r b o n a t er e s e r v o i r so c c u r b e t w e e n thed e p t h sof 500and2,000 meters,a nd71p e r c e n t o f the S o v i e t gasd e p o s i t sa re atd e p t h s oflessthan 2,000

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meters.h eSoviet p e t r o l e u m - I n t e n s i f i c a t i o n p r o j e c t s all h t i v eemplacementdepthso f a b o u t1 , 5 00meters.H e a t i n g

Hie S ovi e ts a c k m w l e d g e theg r e a ta m o u n to fe n e r g y d e p o s i t e dasheat,but,b e c a u s e r o c ^ i s a re such p o o rc ondu c tor s ,t h e ystresst hel oc a ln a t u r eo fItse f f e c ta n d l:sI n a b i l i t y toh e a t l a r g em a s s e s o fo i l - b e a r i n grocks.heradial e x ts ntofs i g n i f i c a n tt e m p e r a t u r e r i s eis cited b y K e d r o v s k l y a n d M a n g u s h e v (19^7)as:

R t=24.7 W1/^ 26)E v e ns u c hl o c a l thermal e f f e c tsm a y w a r r a n t s p e c i a ladditionalstudy,p a r t i c u l a r l y since18 p e r c e n to fS o v i e toi lreservesin c a r b o n a t er e s e r voi r s h a v e viscositieso f m o r e than50c e ntl p ol s e s ,an dm i g h t b ea m e n a b l e toth e r m a ls ti m u l a ti on.owever,t heexperimented, oilfieldte s t wa sconducted ina solution-gas-drive oilw i t h av i s c o s i t y o f6 c e ntl p ol s e s ;asindicated in F i g u r e Ik, the temperature w o u l d haveto h a vea naverage r i s eo f 10"C o v e r asizablev o l u m eo f r o c k toIncrease theultimate r e c o v e r y f r o m ther e s e r v o i rb y asm u c h as1 0p e r c e n tt h el i k e l i h o o do f a n y a p p r e c i a b l es t i m u l a t i o nb y h e a t i n gat thiss i tec a n b ec o n s i d e r e d ne g l i g i b l e ,an d nonew a s o b s e r v e d(Kedrovskly,1970).R a d i o a c t i v i t y

T heSovietse x h i b i tcomplete aw areness oft he t h e o r e t i c a l i.de m p i r i c a ld a t a o n r a d l o c h e m l c a lp h e nom e na .owe ve r ,K e d r o v s k l y a n dM a n g u s h e v(1967) b l u n t l ys ta te thatw i t h p r o p e rd e s i g n of de vi c e ,borehole,a n d s e a l e rthat"oneca na v o i dc o m p l e t e l y th er a d i a t i o ncontamination of th ea tm os p h e r e ,o f th e w o r k regi on,a ndo f t h ep e t r o l e u m b e i n g ex tr a c te d."a n g u s h e v a ndZ o l o t o v l t s k a y a(1969)p r o p e r l y e m p h a s iz e th a tm o s t r a d i o a c t i v i t y(8 5to90p e r c e n t )isen-tr a p p e d i nthei n s o l u b l e residual melt,an dp o s t u l a t e th a tt h e rema in -d eris s c a t t e r e du n d e r g r o u n di nt hef o r mo f s h o r t - l i v e di s otop e s o fi ne r t g a s e sw h i c h c a n b ee a s i l y c onta i ne d.n y c o n t a m i n a t i o no ft h ep e t r o l e u m p r o d u c t s c a n b e controlled b y d e l a y i n g e x p l o i t a t i o n o rd i l u t i n gt h e m w i t hu n c o n t a m l n a t e dp r odu c ts .hus,t h eSovietsseen o real threat o f a n y r a d i a t i o nd a n g e r in u n d e r g r o u n dn u c l e a rex-plosions f o rp e t r o l e u m i nte ns i f i c a ti on.n eb e n e f i c i a l p r o d u c t o fe x p l os i onsin thec a r b o n a t er o c k sa tS o v i e t sitesisthe p o t e n t i a l l yl a r g eamount o fC O g th a tw o u l d b e r e l e a s e d(Taylora n dothers,1970).This release m i g h tl e a d to a s i g n i f i c a n tIncreaseinf o r m a t i o npres-s u r e and ad d t op r odu c ti vi ty .

Ih eSovietss tr e s sth a ta t thec o m p l e t e d te s tin th e e x p e r i -m e n t a loi l f i e l d,o i l wasp r o d u c e d throughout t heo p e r a t i o n f r o m the

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a dj a c e nt we l l sa nds u b s equ e ntl y f r o m r e e ntr y we l l sinto the c h i m n e yw i t h nor a di ol og i c a l c o m p l ic a t io n s.

S e i s m i c i tyThe S ovi e ts u n d o u b t e d l yh a ve c om p l e te d o c u m e n t a t i o noft h e

seismicenergy rel ea s e f r om th e i rn u c l e a rex p l o s io n san ditsp ote nti a lhazards.e d r o v s k l y a n dMangushev(1967)s u g g e s t th a t w i t hthe p r o p e rc h oi c eofsize o fde vi c ea nd p r op e re m p l a c e m e ntp ro c ed ures ,iti squi te p os s i b l et oh a vee x p l os i ons w i t h i nop e r a ti ng f i e l dsw it h -o utd a m a g i n go t h e rb or e h ol e so re ng i ne e r i ng s t ruc t ures.a n g u s h e va ndZ o l o t o v i t s k a y a(1969)e m p h a s izet h es ta b i l i tyoftheb o r e h o l e sands u r f a c ei ns ta l l a ti onsat t he U .S .Gnome,Salmon,a nd G a s b u g g ysites,a ndsuggest 10-to20- k t e x p l os i onsc a n b es a f e l yc a r r i e d outat di s ta nc e sof20to30k i l om e te r sf r o m largei ndu s tr i a lan dIn-h a b i ta te d centers.he d e t e r m i n a t i o nof th e'ainimumsafe di s ta nc eu l t i m a t e l yb e c ou e s a n ec o n o micquestion b a l a n c i n ggaina g a i n s tp o t e n t i a l loss.

Hiee x p e r i m e nte d oi l f i e l dt es t a l r e a dy conducted,the l a r g e s tb l a s t o fw h i c hw as 8kt,c r e a te d n o s eis micda m a g e(Kedrovskly,1970)toa d j a c e n t op e r a ti ng wells,t he c l o s e s tofw h i c h we r e w i t h i n100to120met ers ,b u tsomech.mneysf e l l a n d p l a s te r wasc r a c k e dinstruc-tures1 , 500to2,000m e te r s f r o m t hesite.a r g e r y i e l dsc ou l d h a veb e e nu s e din suchc irc um s t a n c es.E c onom i c s

F r o m a va i l a b l e data,itisi m p os s i b l etoItemize c os tf a c tor sf o rn u c l e a rde vi c e so r sited e v e l o p m e n tw i t h i nt heU.S.S.R.f de-vi c e p r e p a r a t i o nc o s t s area b s o r b e d u n d e r o ne a g e n c ya n d n o t p a i d b ythe p e t r o l e u m - i n t en s i f i c a t i o n o p era t io n ,then th e p r op os e dp r o j e c t sw o u l ds o o n p a y f orthemselves.he a nti c i p a te ds a v in gsof5to6m i l l i o n r u b l e sintheSchemeIp r o j e c tc ou l d e ve n c ove rth e c o s t ofthe device.ll op e r a ti ons a p p a r e n t l y a rea imed a t thes p ec ificec o n o micg oa l so fgreater,faster,andc hea p erp r o d u c t i o nno tde-v e l o p m e n t o fm a r g i na l de p os i ts w i t h que s ti ona b l efutures,b u tstepped-upe x p l o i t a t i o nofk n o w nq ua n t it ies.uch a f r a m e w o r k m a y p e r m i tm or e a c c u r a teec o n o micp r e di c ti onsan d d ev el o pavi a b l e p a y - a s - y ou -gos y s te mo f p ro j ec t s.heS ovi e tsh a vede c l a r e d th a t p e tr ol e u m -i n t e n s i f i c a t i o np r oj e c ts a ren ol o n g e rex p erimen t a l ,a ndchat t h e ya rep r e p a r e dto o f f e rthisserviceto o t h e r countries.

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SUMMARYU n d e r g r o u n d n u c l e a re x p l o s i o n s h a v e ob viousa p p l i c a t i o nas

p o s s i b l e e n e r g ys ourc es f o r t hes t i m u l a t i o nofn o n c o m m e r c i a l o rde-p l e t e d p e t r o l e u m dep os itstoinc rea s e b o t hp r o d u c t i o n ra tesandu l t i m a t er e c o v e r yp erc enta ges.he p r i n c i p a l b e n e f i c i a l p h y s i c a leffec t o f s uc h a n e x p l o s i o n ist hec r e a t i o nofa ne x t e n s i v e p a t t e r no f f r a c t u r e sp e r m i t t i n g b o t hm o r era p idf l o w of p e t r o l e u mto w e l l sa n di n c r e a s i n gp o s s i b l e h y d r o d y n a m i c p re s s u r e s o nthedeposit.heb e n e f i c i a leffec t o fh e a t i n gb y s uc h a n e x p l o s i o ng e n e r a l l y ha s b i . e nc o n s i d e r e d i s r a a l l a n d localized,b utthisc o n c l u s i o nm a y h a v eto b erevic eda f t e ra l l t he d a t af r om t heR u l i s o np r o j e c th a v e b e e neva l ua ted.Ther a d i o l o g i c a la n dseismic hazards o fs u c ha n e x p l o s i o n m u s t b ef u l l yu n d e r s t o o d a n d t a k e nintoa c c ount,b u t b o t h a p p a r e n t l ya rep r e d i c t a b l ea n d c ontrol l a b l e.c onomicb a rriers ,p a r t i c u l a r l y t he c o s t o f t hen u c l e a rdevic e ,r e m a i n thep r i n c i p a ld e t e r r e n ttow i d e ru t i l iz a t i o n ofthisa p p l i c a t i o no f n u c l e a r energy.

Both the U .S .a n d the U.S.S.R.h a v ea c t i v e e x p e r i m e n t a l p r o g r a m sc o n c e r n e dw i t h p e t r o l e u m - s t i m u l a t i o n p rojec ts.tis h o p e dth a t thisp r e s e n t a t i o n o f a v a i l a b l ed a t a o n the e n v i r o n m e n ta t the P l o w s h a r esitesint heU.S.a n dc o r r e s p o n d i n gs itesint heU.S.S.R.p r o v i d e sab a s is f o r c o m p a r i s o n o f thes t a t e dA m e r i c a na n dS oviet p h i l o s o p h ya n dt e c h n i c a lcriteria.x t e n s i v ed e t a i l e d d a t ah a v eb e e n p u b l i s h e d o nthee n v i r o n m e n tatU.S.sites,p a r t i c u l a r l yf o r thep r o j e c t sinprogress,G a s b u g g y a n dRulison ,b u t a l s o i n c l u d i n gthe p r o p o s e dD ra g o nTrail,Wa g o nWheel,a n d WASP.a i r l y s p ec ificd a t ar e c e n t l y h a v e b e e nr e l e a s e d b y t heS o v i e t s o n t h eo n ea d m i t t e d e x p e r i m e n t a lo i l f i e l dsite,a n d m o r e l i m i t e dd a t a ha ve b e e np u b l i s h e d o nt hee n v i r o n m e n t o fthep r o p o s e d s itesf o r Sc hemesI a n dI I .hea v a i l a b l ed a t a c l e a r l yin-dic a tes i g n i f i c a n td i f f e r e n c e sinb o t h a p p r o a c han dob j ec tives;t hec o m p a r i s o nt a b u l a t e db e l o w a n d s h o w n i n F i g u r e25 emp ha s izess uc hdifferences.

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F e a tu r e U .S .S ta te m e nt U.S.S.R.S ta te m e ntStatedPu r p os e Raises u b m a r g i na l d e -

p o s it sto c om m e r c i a llevel.

Raisep r o d u c t i o nra t esandde c r e a s ee x p l oi ta ti on c o s t sincommercial, d ep o s it s.

N a tu r eofR e s e r v o i r M o d e r a t ? l yde e p(300to2,500m e te r s b e l o wsurface),th i c k >60meters),

l o w p e r m e a b i l i t y(0.1to1.0 mlllldarcies),c l a s t icsequence(withm o r ep e r m e a b l es a n d s)ofu p p e rCr e ta c e ou sage;s t ra t igra p hictrap.

Mode r a te l y de e p(500 to2,000m e te r s b e l o wsurface),th i c k >60m e te r s prefer-able,30 to60 m e te r sminimal),m ode r a tep e r m e a b i l i t y( 1to100 millidarcies),c a r b ona te sequence(withh i g h e r p o r o s i t y zo n es) o fPe r m o- C a r b oni f e r ou sage;s t ruc t ura ltrap.

N a tu r e ofP e t r o l e u m

N a tu r eo fC a p

N a tu r a l gas(o rl o wv i s c o s i t y o il ?)w i t hd e p l e t i o ndrive.

Thick,I m p e r m e a b l ec l a s t icsequence.

N a tu r a l gasoro ilw i t heit herd e p l e t i o ndr i veo r w a t e rdrive.

Thick,i m p e r m e a b l es a l in esequence.

E x p l os i on With i nr e s e r voi r toI n c rea s e p ermea b il it y. With i nr e s e r voi ro r b e l o ww a t e r in t erf a c e t o i nc r e a s ep e r m e a b i l i t ya n dw a t e r drive.

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R e f e r e nc e s

Atkinson,C .H.,a n d Johanson,R .T . ,1964,A s t ud yofthe fea s ib il -ityof u s i ng n u c l e a rexplosionstoi nc r e a s ep et ro l eum recovery:U .S .Bur.Mine s Rept.I n v .6k9h, 18 p.Atkinson,C .H.,Ward,D .C, an dLemon,R .F.,1970,G a s b u g g y

r e s e r voi re v a l u a t i o n -1969report,inS y m p o s ium o nen gin eerin gw i thn uc l ea r explosives ,Proc,v .1 :m.N uc l ea r S o c .a n dU .S .A t o n icE n e r g yComm.CONF700101,p.722-731.

Boardman,C .R.,1970^E n gin eerin g e f f e c tsof un d ergro un dn uc l ea r ex-plosions ,in S y m p os i u monen gin eerin gw i t h n uc l ea rexplosives ,Proc,v .1:m.N uc l ea r Soc.and U .S .A t o m icE ne r g yConm.,CO N F700101,p.43-67.

Boardman,C .R.,Rabb ,D .D.,a n d McArthur,R.D. ,1964,C o n t a in ednu c l e a rex p l o s io n sinf ou rmed iageo l o gic a l factorsinc a v i t yandc h i m n e yf or m a ti on ,in E n gin eerin g w i t h n uc l ea rexplosives.P l o w s h a re Syinpoeium,3rd,Proc:.S .A t o m icE ne r g y Comm.,TID-7695,P .109-126.

Boardman,C .R.,a n dSkrove,J. ,1966,D i s t r i b u t i o nin fracturep erme-a b il it y o fagra n it icr oc k massf o l l o w i n g a c onta i ne d n u c l e a rex-plosion:pur.Pe tr ol e u m Technology,v .18,p .619-623.

Cauthen,L .J. ,Jr.,1964,S u r ve

environments at us and ussr nuclear explosion sites petroleum stimulation projects 730510

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