.

9 PACES●

SPESPE 17716

Breakdown Procedures Designed to MinimizeNaturally Fractured Reservoir Damageby P.T. Brtitti3g8tI” andR.H. Wilmer, CER Corporation

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ABSTRACT ~C4J~ON AND RACKCROUNO

Damage to natural fractures have been found Completionpracticesassociatedwithnaturallyto occurae a resultof conventionalcompletion fractured reservoirs should differ aarkedlytechniques previously employed at the DOE from those routinelyapplied to homogeneousNultiwell Experimental (MWX) Site. In an resemroirs,primarily becausetheinterventionattempt to understand sorae of the damage processes in the high con$iuctivityfracturesmechanisms and find mitigating techniques differconsiderablybothinscopeandmagnitudethat could be practicallyemployed, a eeries from the tight.matri.xalone.The first diffi-af ratherunconventionalcompletionprccsduree culty occurs in ●stablishingthat the targetwere performed.Theseprocedureswere designed reservoir is or is not naturally fractured.to utilize gases rather than aqueous-based This may beccmeevidentfromdrillingrecorde,fluids during the perforatingand brealcdcx#n/visual observations of fracturee recoveredIQicrofracturingprocess and were performed in core oran establishedpolicy definingthein several differing reservoirs. Previous reservoir to be fractured.since the salienttests at the NW undemcorad the impairment damage mechanisms in naturally fracturedtonatural fractureflowcapacitythatresulted reservoirsdepend almost entirelyon interac-from liquid invasion during perforating, tion with the natural fracturns, the nextbreakdowns or large scale stimulation.Thus,the use of gases duringthe initialconnection

problem in achieving an effectivecompletionisto take everyprecautiontominimizeimpair-

into the naturally fractured reservoirs at ment to flow in the fracture system. Matrixthe MWX was considered a natural starting damagecanultimatelyaffectoptimumproductionpoint. but when the primary flow pathe are natural

fractures,thentherelativelossesareclearlyThe completion techniques that were tested much greaterwhen the fracturesystemproduc-and that will be discuseedemployednitrogen, tion capacity becomes impaired.N2, during dry hole perforating;as a fractur-ing fluid during simultaneous perforating During the course of extensive testing atand fracturing: and in an impulse remedial the MultiWellExperimental(NW) site locatedtreatment.ktestof a tailoredpulseexplosive nearRiflet Colorado,over60differentperfor-techniqueprovideduaefuloperationalinforma- tion and breakdownprocedureswere performedtion but inadequate wellbore preparation in avariety of naturallyfracturedsandstonescompromisedan assessmentof itseffectiveness and other litholcgicunits.The projectobjec-to createamultiple fractureset.Theapplica- tivesforNWX testingxweremostoftendesignedtion of theee unconventionaltechniquespro- toyieldreservoir productim characteristice,vidad a very useful and unique set of test in situ stresses and/or details of hydraulicdata and proved to be sufficientlyeffective fractureinteractionandenhancement.Althoughinpsrmittingtheengineerstoacquirepositive it was not the expressedintentof the projectpreesure interferencedataduringa subsequent to determineor evaluatespecificperforationwell test. and/or breakdown techniques,it was critical

that the original reservoirsystem (thatwas

References and illustrationsat end of paper.quickly understood to be highly naturallyfractured) not be unalterably affected by.

BRBANOOWN PROCEDURESDESIGNED2 TO MINIMIZE NATURALLY FRACTUREDRESERVOIR DAMAGE SPE 177X6

ttmseor any other secondsryprocasses.Thiswas partkul.arky trw durhg wall and int@r-feraneatesta that wor* aonduot:adin 10 8*par-ato tight Haeavordo candetons resomoirs.l?msorasarvoirs involvadavariaty ofdopoA-tionale!Wironmant sincludingMarina,Coastal,Paludal and FluVial.Some of thase resavoirswers axtenaivablankatsandstones,otlmrswerelent~oularboth largoand small.All containedaxtrezmly tight mstrix rooks with low poros-ity2~3 and were naturally fraoturod.

Figurel is an aroalview of the threeclosaly-spacad NW experimentalWS1lS that penetratedalmost tho entire !fesaverdeinterval.It canbs seen in Figure 1 that the shortestdistancebetween wells is 110 ft, while the longastdistanceis210 ft.This closespacingaffordedan excallent oppotiunityto attempt pressureinterferencetasting during the long periodsof pre- and post-stimulationwell testing.Since the pressure transients that might beobsened at one of these offset wells wasexpeotad to be on the order of 1 to 10 psi,it was clear from the outset that little orno damage would be acceptable,pertioularlyin the natural fractures surrounding theobservationwell~.

!rheprimarygoalsofthe initialNNXcompletionprogram, which involvadportionaof the drill-ingoparationa, parforatingandbreakdown/mi-crofraoturing,were explicit:

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m.in~ize drilling mud invasion in theseoverpressuradreservoirs:

establishan undemagedwellboretoreser-voir aonneotionfor all three wells; and

significantlyraducethevolumaofliquidsinjeoted int~ the reservoirand naturalfraoturesystamduring finalcompletion.

Numerousattampts weremadeatwell completionsusing conventional techniques that includedvariations of jet oharge and bullet perfora-tors, medium (100 BBL) to small (20 BBL)volumes of non-damagingwater-basedbreakdownfluids,anddivertingball ealers.Theresultswere occasionallymixed4~ ~ and oftenprovidedconfusing eets of information.Most importantwas the faotthat nearwellboredamageeffectswere usuallydiminishedin the p?xxiuotionwellduring the course of a 60 te 70 day test,but the observationwelle most often did notappear to recover.

CONVENTIONAL ~ONS

As an introduction into the more complexnaturallyfracturedreservoirs,firstconsiderthe typioal completion procass in a ratherconventional reservoir, assumed for thisexample to be both homogeneousand isotropic.Typically, initial completion praotices incaeed welle involve one or a combination ofthe followingprocedural:

e jet or bullet perforating,

-.

● hydraulic breakdown/microfracturing~and

● large soale propped stimulation.

:n●seence, ●conomics drives which of thesemocedures are followed or required. Whenhe productive reservoi= turns sut to be a:ightformation,then it is almosta certaintyhat all of the above procedures, includingk large scale stimulation,will be mandatory.fthe well is to be made an economicventure.

?igure2 is an isometricdrawing for a convan-:ionalcasewhioh, in r8therelementarYte-,~howsa cased well with a oement sheath thatlas bean perforated and ZIiCrOfraxUrad=?ach of these procedures conceptuallyyieldsomebenefitsto productionwhile in reality,t!ielddata and laboratory tests indicate anixed set of zaaults. without going intothedetailsof each individualprocws’sbene-Eits and liabilities,it will be sufficientto say that there is considerablecontroversyin definingjust what constitutesthe optimum.procedure. For example, even though manyengineers may consider perforating to ba arathersimple,straightforwardand reasonablywell understood process, the fact remainsthat considerable effort has been expentiedin quantifying individualand composite ef-feots.6-9 In an SPE distinguished authorsseries, Bell 0 presents a summary of ourrentperforation praotices with a slant toward apartioulartechnique,andyetitisnotwitboutcriticism.ll It is sufficientforthispreeen-tation to state that ideally, perforationsare axpeoted to penetrate the steel CaSin9,cement and formation and provide a highlyconducive flow path along its entire lengthwhile ~inimizing compaction or other formsof fern.tiondamage.

In the event that Perforatingalone doaa notprovidesufficientproductionjorwhanpertora-tions yields restricted, uneven or damagedflow patha, then some form of breakdown/mi-crofracturingis performed to mitigate theseundesirable effecte. AS seen from an arealview in Figure 3, a small fraoture”extendsfrom the wellbore through the perforationsand into the formation.

lts len@’ ‘f’a%determined by the physical, rheologicamechanical properties of the formation andfracturing fluids, whila fracture directionis a functio~2,0~3the present day in situstresaee,ui.

Themicrofracturingproceesganerallyconsistsof pumping a low viscosity, ‘non damagingmaqueous fluid at sufficientlyhigh rates toinitiateand propagate a short fracture thatemanates from the perfs and ext%nds be o

x Wthe damage zone.The use of ball sealers,l #or oth$rdivertingagentsduringmicrofraotur-ing should provide adequate control of fluidand fracture placement. Azauming that thereeultingfracturmprovidss a high dimension-lessflowcapacity,Fcd16,thenwellproduotiv-ity should return orbe slightlygreater’hanthat achievedthroughidealperforatingcondi-

.

SPE 17716 P.T. BRANAGANAND R.H. WILMER a---- --- .

Lions. As shown in Figu%. 3, ‘non-damaging* Tho intsrsmtion probabilitycurvo of FigureCluids don’t always act id~ally under in 6 implie8 that there is a reasonably low~itu conditions and may leave 8oma residualImpairmentto natural matrix flow capacity.

probability for an itioalperforated well tointoreact natural fractures that ars spaaad

L!hewallwould then eithGxbe putonprcduction greater than 6 ft. Furthormor., ●van undo=malarg~scala stimulationwotidboperformad tha best of ckmmstancos, intorscctiondoessimilar tn tha miorofracturcbut containing not guarantee that tha wall will prcduo9E propping agent. ~c problems associated ●fficiently, and thus, some form of break-witblargeproppadstimuLationediff*rprimar- down/microfracturingwillprobablybere@rad.ilyinscala from thoseof thomiorofractwingprocess,both it:costs and ●ffect. completion Damage HechanisB

In the course of drilling and completingthe~~Y ~~ --oIRS ~ONS well, a numbar of mechanisms may tend to

degrade the original high conductivity ofAwmll beingdrilledintoanaturallyfraoturad the natural fractures. Some ofthe89 mechan-reservoir that contains vertical fractures isms include the invasion of drilling mudhas an inherent probability that it will that may ultimately act as a plug, cementsintersect one or more of those fractures. squeezed into the fracture,perforationsandFigure 4 shcwsan arealviowofa hypothetical near wellbore stress changes that could handwell drilled into a reservoir with an average to c108o tho fracture, and tho interracialfracture spacing, S = 2 ft. For this case,it csn be seen that there is a reasonably

tensionalforcesgenerallydescribedbycapil-

high probabilitythat the 10.874I. diameterlary pressure of invaded completion liquidsthat limit fractureflowcapacity.The theore-

drill bit will interssct a fracture. After tical values for a slot or ideal laboratocasinghas been installedandproperlyporfor- ?fractureconductivity,kfwf, has been shownlated, where perforations●xtend an additional to be proportio al to fracture width or apor-6 to 8 in. intothe reservoir,the probability 3ture cubed, wf .for natural fracture intersectionincreases

Data comparing ideal to

slightly.real apewes for medium to very small frac-

For somewhatlarger fracturespac-ings, S = 5 ft, the probabilityof fracture

turos, compiled by Ba%tOn,l*shows that real

intersectionwill drop rathareharply. Figureapertures range between 0.2 to 1.0 idealapertures. Combining the work of Barton

5a is another conceptualcase of a perforated and idealaperturevalues, fracture conductiv-wtillin a reservoirwithS = 5 ft,while Figure ity, kfwf, is the somewhat familiar cubic5b depicts the same case exceptwhere a small form,breakdown was included.

kfwf = a x 54.4 x 109 x Wfs (1)To quantify the probabilityfor a drill hole,core sleave and or a cased and perforated where,wall to intersect a natural frae:.ure setwith spacing, S, a series of Xontd 73rlo kf _ natural fracturepermeability (red)calculations was performed. Figu%e 6 is acomposite set of cumes for different well Wf = natural fractme aperture or widthconfigurations that shows the intersection (in.)probability verses fracture spacing, S, ofam oticgon6\l square fracture act. curves a = ~fion*s JRC coefficient (0.3)are presented fer a 10.87-in. drill hole , a+in. core sleeve and a completed7-in. cased Equation (1) shows the significance thatand perforetudwell with 6-in.radialperfora- changes in width have on conductance,whethertions. Nota that We intersectionprobability thewidthalteringprocessmechanicallyreducesfor the perforated cased well in a fracture the actual aperturelallgor intrusiveliqu,idssy5tbsm with s = 5 ft, is 37 percent. Thus diminish the availablecross section throughtiers is only about a one in three chance which gas can flow.that this well might cross a fracture.Thatprobability falls to almosti10 percent or As ah example, “the fracture permeability,about a 1 in 10 chance that such a well will

‘?for a o.0005-in.wide aperturefrom Equa-

intersectfracturesspaced 20 ft apart.Addi- t on (1) is found to be about 4,100 md.tionally #i@ conputar-generated data set Raducingthe effectiveaperturetowf= 0.0001shows that there is only a 12 percent chance in. decreases effective gas permeabilitybythat a 4-in. core will yield a fracture even 1/(5)2 or to kf = 160 md, and kfwfby 1/(5)3.when the fractures are spaced as close as 5 At first blush, kf = 160 md might appear toft. This suggests that if a natural fracture be a rather large permeabilitywhen dealingis obsen?ed in core, then fracture spacing with a ‘tightN matrix resem?oir. So consideris three times more probable to be spaced a fractured reeewoir with tight 0.001 mdless than 2 Et than spaced greater than 2 matrix rocks, ~ , with the initial fracturesft. Fractureswill undoubtedlybevery closely spaced, S = 10 ft, and with a kf = 4,100 mdspaced if they are observed in core. These and wf = 0.0005 in. This case has the initialproba’)ilitieswon’t change appreciablyfor a matrix portion of conductivity,

Ys = 0.01

rectangular or nearly unidirectionalset of md-ft, while the fracture conduct vity partfractures. The intersection probability,in yields kfwf = 0.167md-ft. Thus, the fractureessence, raprasents the shortest spacing tomatrix conductivityratioisabout 16:lwithbetween fracturasand is independentof asym- the primary flow conduit being the naturalmetry. fractures. However, raducing the fracture

SREANDOWN PROCEDURESDESIGNEDTO HXNXNIZE NWURALL Y FRACTUREDRESERVOIR DAMAGE SPE 177%6-.

width tO w = 0.0001 in. now causes fra+ur.{

a produsing well. Then this small p= willoonduotiviy to fall to kfwf D 0.0013 nd-ft, tend to mask the real reservoir prassurewhich is then considerably less than the distribution until pressure differentialsmatrix conductivity, Ic@ - 0.01 md-ft, end cause tbe water to beoome mobil.is no longer thO primary flow conduit. Sothe ruult of this small ohanga in sffective It is clear that the integrityof the naturalfracturewidth Seem 0.0005 in. to 0.0001 in. fracture system must not be abridged by thecausema significali?.alterationin the primary interventionof the well or completionprooe-resemoir flowregime.In fact,averagereser- dures. Xfthe fracturesare adverselyaltered,voir permeabilityhas gone from its initial then the process needs to be reversed, ifvalue of: that impossible, or avariation inthecomple-

tion process must be considered which will~ _ ((J0167md-tt + O.O1O md-ft)/10 ft mitigate or at least minimize any fracture

- 0.017 md damage.

to the reduced value ofNON-AQUEOWSHNX ~ON ~CE

z = (0.0013md-ft + 0.010 md-ft)/lo ft= 0.0011 md During the latter segmentsof the NW project

efforts were made to acquire additionaldatawhioh is ●ssentiallythe matrix pe~eability concerningnon-aqueousformsof microfractur-alone, and the system is now truly producing ing. The primary intent of this addendum tofrom a tight resen?oir. the project were several fold:

Liquidspresentinthenatural fraoturesy&Xm, ● attempt several different completionineffeot, limit the availablefractureaper- techniques using nitrogen, N2, gas inturo through which gas can flow. If watek is the same formation;used in the breakdown process, then it willundoubtedlyfillmost of thensarby fractures. ● compare results from a tailored pulseWhen the well is then put on production,the explosive fracturing echsme with N2injected water must ●ither be removed from date; andeach fracture through the wellbore or itmust be allowed to imbibe into the matrix. ● gainadditionalknowledgeandunderatand-Otherwisegaseous flow willbe almost totally ing into natural fracturedamagemachan-impeded. ~er ,whenwaterproduotion ishigh isms and mitigating effects.enough such that a full column of water sitswithin the well and cwers the perforations, Several.different breakdown/microfracturingthen the greater yxtion of the underlying techniquesusingnon-aquebusformsoffractur-natural fractureswill be filledwith water, ing fluids were performed in three differentagain limiting ●ffective gas permeability. naturally fractured resezvGirs at the NNX~is problem is not a pressure problem but s~te. These techniques,except for a tailoredthe inabilityof the gasto flow horizontally pulse explosive test, 811 involved only thethrough the water. In effact, the relative use of N2. The techniques included:gas permeability of the fraoture has beengreatly reduced. ● h@HIUliC N2 fracturing using SUrf8C6i

pump trucks,There is one additional caveat concerningliquids present in the fracture system and ● perforating with an underbalanced N2that involves fracture capillary pressure, column,PC. For an ideal set of parallel plates, Pcis of the form, ● .highpressureN2 impulseperforating/mi-

crofracturing,p= = 1.142 X 10-5 X YX COS (?/Wf# (2)

● N2 impulse injection using a tubingwhere pump out plug, and

PC = capillaq prassure, psi ● tailored pulse explosive fraoturin~.

Y = titerfacialtension, dyne/em PumPed Hydraulic N2 Racturing

t?. mgle between wetted surface and The initialuses ofN2 at the NWX site involvedwetting phase surface (0). several breakdown and step/rate injection

tests in both Coasta120and Fluvia121environ-For @ = 0°, Y= 72 dyne/em for water and gas, ments.and wf = 0.00C1 in., the capillary pr@S8tUe

The primary intent of these first

iS pc = 8.2 PSi.tests was to establish closure stress and

That may appear to be a fracturingpressuredata for impendinglargerimperceptible value considering that the propped foam fracture treatments, and thus,reservoirpressures are on the order of thou- the enhanced production capacity effects ofsands of psi. But for remote locationswithin these N fractureswere never fully examined.the resenfoi~, pressurm differences will be iFraotur ng was performed using high rate N2on the order of 1 psi, suoh as that mentioned pump trucks where the maximum rates exceededpreviously for the anticipated observation 20,000 SCFN and injucted VOIUX@S t0talin9well pressure of 1 to 10 psi at 120 ft from almost 1,000,000 SCF. During the course of

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thasc treatments,measurementswars routinoly well, MWX-1, oalled for 19 gm jat ohargo1

mad. of surface injsotion rates and volume, perforators, vertically spaced 2 pu footand surfacs prusurc and bottomholepressure. and phamsd 120°,to be datonatadin tha Ozmingslz~e kho volumes WSE* usually rathar large, that aontaincd high prassura N2. Bottomholethese treatmentsprobablyrasu.ltadin raason- N pressure was sat to ●xceed frac prossum.ably long fractur~ lengths. As a rasult, Z&B soheme,tarmedN~ impulsa perforating/mi-thasa tests would not provido an unambiguous crofraoturing,was dssignad to simultaneouslyassessment of near wellbora ●ffacts nor tha perforats the well and at the sam tire,●f faotivenass of small gaseous brcakdowna to crest. fraotuma that would extend from thconmot tlm wallborewith tha existingnaturalfraoturo sat. Tharo would always remain some

w811bore and intors~ot the natural fraoturesystem.

uncmtainty that tho lengthyartificialfrac-turewould,by itsown presence,substantially Figur* 8 is an artistcs conception of thOenhance prcduotion. test well, MWX-1, showing the prtscd.bad

bottomhole pressure prior to perforatingandFlowback and short production tcets did, the looation of the easing jet perforators.however,showthatthesetreatments succsssful- Sinc*. the observationwell, NWX-2, had pre-ly enhanced production substantially above view !,ybeen perforated, this p~ovided anthat which was possible from the matrix alone. ●xcellentopportunityto observe the N impulseThe use of N2 as a nondamaging stimulation perforating of MWX-1 at a ramte %cstionfluid in other fraoture-ssuoh as thfaDevonianshale?q~%%~%%*~p~%&

within the same reservoir (refer to Figume1 and 7). A high acouracy quartz pressure

to be successful;now theseMNX tests (although gauge was emplaced in the bottomhole of NWX-limited in scope to very short test periods) 2 and seated in c bottomhole shut-in devicehad shown that th?se naturally fraotursd and provided an excellent data set.14esaverde sa@atones could alsobe ●ffectivelystimulatedwith N2 alone. Figure 9 is a composite graph showing the

measured surfacs pressure in the frac well,Perforat* in an Underbdanoed column of I?2 NWX-1, and the reservoirinterfereme pressure

being obsemed in the remote well, MWX-2.To quantify the ●ffectiveness of N

ias a The initial pressure increase seen as steps

perforationbreakdownfluidaaerioeof if fer- in MWX-1 ocourred during the N2 fillingpro-ing tests were soheduled to be performed in cess. The total volume of N2 used to filla shallow (5,550ft) FluVialsandstone,desig- the 7-in.casingwas350,000SCF. Aftersurfacenatsd the FluVial E. A slightly different pressure was brought to about 6,000 psi, theprocedurewas eohaduled for ●aoh of the three jet ohargeswere firedandtheWC1lwas perfor-MWX wells. Figure 7 is a schematic cross atsd. Assuming that all the jet charges firedsaction of the three NWX wells and the log, simultaneously or at lea?t wi+hin 1.0’sofcore and sedimentologkally derived position millisecondsof ●aoh other, then ●aohperfora-of the Fluvial E sandstone. tion was subjectedto approximatelythe same

high preseure N2 impulse.Fracture extensionThe first test involved perforating one ofthe observationwells, MwX-2, with 20 gm jet

presnura derived from step rate and in 81 ustress tests was found to be 4,8!50psi,$6

charges vertically spaced at 8 per foot in thus the initial N2 pressure at the sandanunderbalancsdcolumnofN2.Surfacepressure face was at least 2,000 psi above frac pres-suring perforatingwas about 1,000psi, which sure.for a full N2 column correspondedto a bottom-hole pressure of just about 1,200 psi. This The dynamics of this N2 impulse fracturingpzocedure differed markedly from the normal are such that it is more aptly described asperforation procese which were most often explosiverather then injective.The compres-performed under a hydrostatic column of 3 sional energy stored in the high pressure Npercent KC1 water. It should be noted that column is almoat instantaneously releaseiall of the different sandstone reservoirs into the perfs the moment they are created.tested at NW!!exhibited reservoir pressure An expanded view of the pressure data asconsiderably in excess of hydrostatic,25 shown in Figure 10 discloses the speed withranging from a gradient of 0.82 psi/ft to a which N2 pressuredroppedfollowingperforat-low et 0.58 psi/ft, and thus, were all slgni- ing. .Theaverage fracturing/injectionrateficantly overpressurad. Although this under- during the first 45 sec after pe f~f~~~balanced perforating case was not expected was about 75,000 SCFN. cuderman2;toprovide thebest connectionwiththenaturalfractures, as detailed in the intersection

several fracture regimes for a variety ofpressure pulse rise times. Although this

probabilityourves,neverthelessthewellafter impulsewas fast it was well within the linearperforatingindicatedthatitwascommunicating elastic region of theee seWzentary rocks.quite effectivelywith the natural fractures. Using cuderman’scriteria,thisprocess shouldConsidering the intersection probability fall under the hydraulic fracture ostegory,ou?we in Figure 6, this test indicates thatthe natural fzacturee were most likely very

as opposedto multipleor explosivefracturingcategories that require pulse rise times of

closely spaced. less than a few milliseconds.Unfortunately,surface pressure recording from the frac

N2 Impulse Perforating/Microfraoturing well, MWX-1, failed fOr abcut 1.5 minutes

The N2 breakdown scheme for the productionduring which time the surface pressure fellbelow4,100psi orthe correspondingbottomhole

BREAKDOWN PROCEDURESDESIGNED~ MINIMIZE NATURAJ‘ Y FRACTUREDRESERVOIR DAMAGE SPE 17716

uctsnsionprcssuraof 4,850psi. Thus, saleot- Rayislgh wsvos inductd on the surface ef theLng closuro time is not without uncertainty. stesl easing or asmont.

Furtherinsight into this fracturingprocess Tai20red Pu2ss Explosivo:an be seen from a review of the log-logpreswre/derivative pressure groupza plot Surface pressure measurements following thetiown in FigUr@ 11. Surface differencepres- initialperforatingofHWX 3 did not indicatemum, DS1 p, shown in FigUr@ 11, corresponds that theperfs hadconneoted with the existingto the injeotion pressure minus the initial natural fraoture syetsm as had been the caseCraoturing pressure which was taken to be withMwX-2. Thus,the tailoradpulse explosive6,011psi. The early time portion of Del p, breakdown prooedure that was eoheduled forandderivativedatadisplaysa ratherconstant MWX-3 was not just an acadamifJendeavor butslope for the first 0.2 minute or about 12 a necusary one if this well was to aot as ato 14 seaonda sndthen ohanges●ignifioantly. valuable observationlocation for subsegmentThis early time slope is about 0.6 psi/oycle reservoirtesting. Thetailoredpulseexplosiveand is reasonablyclose to the 0.5 psi/oycle breakdown procedure entailed the use of aslope described by Cinco2g that represents relatively slow burning propellant designedlinear flow within a fraoture. considering tocreate amultiple setoffraotures radiatingthe dynamics of this process, turbulence, like spokes from the perforated wellbore. Tobackstresses, and the continuous storage create the correot environment for this tai-vol~e increase as the fraoture is created,it is surprisingto see suoh a close corr*la-

lorad pulse explosive to properly initiate

tion between this data and the ideal 0.5multiple fraotures, a fluid with a densityabout that of water but considerablyin excess

slope. If this 12 to 14 seoond period does of most available gases was required as arepresent the fraoture flow regime, then it tamping media in the casing. Since aqueousis probably the period in whioh the fraoture eolutions wue not judged appropriate foris being created, extended and inflated. this application, then alternate tamping

fluids were considered.Carbon dioxide, CO ,Mditional infomstion concerningthisfractur- ibelow 87.8°Fandl,070pei oanexistinliqu ding process oan be seen in the observation form and thus was consideredto be an idealwell, MWX-2, data. Referrtig to Figures 9 wellbore tamping fluid.At reservoirtempera-and 10, there appears to be two superimposed ture (150° F) and reduced pressure, the C02ptisesocourringinthisinterference pressure would return to its less dense gaseous state,data. The first pulse ooourringalmost simul- thus minimizing any residual damage to thetaneoualy with the perforating in MNX-l has natural fraoture system. Figure 12 detailsa fast rise and fall t.j~ewhila the latterpulse is slower, larger and continues to

the designed wellbore configurationfor thistest.

rise until data acquisitionoaaaed.The firstpulse is nest probably the ramlt of a poro- The test prooadure oalled for ●xcese watermeohanioalreaponsetotheoraation, extension remaining in the wellbore from previous work-and residuals of the induoed fraoture. Thelatter slow rising pulsa is the result of the

over ●fforts in deeper intervalsto be circu-lated from the well, the tubing removed and

diffusive prusure distribution ooourringthroughoutthe natural fracttme system. Note

the easing perforated. The well would then

that the rise time for the first peak isbe pressured to about 1,000 psi with N2,

about 0.3 minute or about 18 to 20 secondspartly filled with about a 2,000-fthead ofliquid C02; then, a 38-lb propellantpackage

and may well represent the period during would be emplaced adjacent to the perfs andwhioh the N2 induced fraoture in MWX-1 is in ignited.the process of significantdeformation.Once

After the propellant was expended

fracture fluidaleakoffa becomesthe dominateand the fracturescreated, wellbore pressurewould be reduced by venting the N2 gas thus

procese,exteneionceases,the fraoturebeginsto close, and the induced stress diminishes.

allowing the C02 to gasify. since the perfor-

Modeling of this reasonably complex set ofated intervalwae longer than our ability toemplace a single propellantpackage of 6uffi-

prooessesis in progressand will represented cisnt length to simultaneouslytreat all theat a later date. perf, the procedure was soheduledto be exe-

cuted in two separate but identicalpasses.One final note concerning the derivative The lower 12 ft (5,562 to 5,574 ft) of thegroup from the MWX 1 data shown in Figure 11 perforated interval was treated first whilewhere a series of damped oscillationsappearsduring the initialesconds of the N2 impulee.

the remainingupper 12 ft (5,550to 5,562 ft)were treated two days later.

The period for these damped pressure oscilla-tions is a fairly consistent 1.8 seconds. With someminor delays,the initialprocedures‘rbeseoscillations may represent a ringinbetween two differing boundary impedances

g appeared to follow the design criteria, and

where the period is the result of the twopreseure impulsemeasurementsat the surfaceindicated that the first propellant package

way transit time for sonicwaves in the media. had burned properly. However? after a shortIf the transmittingmedia is th. high density 12-hr test, the resenfoir did not appear tcN2, then the distance between the boundaries be respondingsince no significantquantitiescould be as C1OS8 as 900 ft. Since this dis-tanoa is considerablyehorterthan the surface

of resemoir gases were apparentin the well-

to bottomhole distance, 5,550 ft, then itbore. Several failuremechanismswere contem-

may represent the fracture tip to wellboreplated including the fact that the prhWX’Y

distance. One other possible solution isset of natural fractures might not lie withinthepo=ionof the reservoirthathadjuat beam

PE 17716 P.T. ERANAGAN AND R.H. WIWSR 7—

fractured. Recall thationly tlm lowar most high flow capacity storag~ vassal for tlmportion of the rmaa~oir bad been ●ffeotivaly impulse, and sacondly and more important,Stimulated by this first test and the upper bottomhole annulue pressure was always main-portion was to bS &Mt@ in tlm secondpasm. tainod at a higherprassurethan ths injectionThersfora, &* wall was reconfiguredfor the pressure at the parf 8. This high bottomholesecond portion of tho test, the W.llbOr@ Waa SIUltiUSpSSSSUX9 would tend to miIlbiZ@ Shyfilledwith th~ nacassaryallocationof liquid loss of injectiongasss throughmicro-annularC02 and N2 ga8, and tho propellant paCkSg8 regionsthat might exist ebovs tha porforatadwas emplaced at tha upper portion of tho interval. When bottomhole tubing presmlreperforated intonal and then ignited. After ●xuaedod tha prescrilxd pin shaar stress,pressure had been rethreadand the C02 was 6,500 psf, the pump out plug opened, creatingpermitted to ●scape, tha wall proceeded to a very rapidpreaaureriseat theperforations.produceonlyvary limitedquantitiesof natural Thie pressure rise to about 6,000 pei shouldgas (<10 MSCFD). Thus, after two separate be sufficiently fast to permit the extensionattempts at using the multiplo explcmivo or at least dilation of the fractures thatfracturingtechniqum,no enhanced production had been dsvelopsd by the tailored pulsewas ●violentfromthiswell. Subsequentinepec- Sxplosivo tests. This process would thention of the casing string showed no apparent dispersmthe ii-wadingwater over a much largerdamage from ●ither of the explosive paakages area am! at least partly restore the nearthus ●laminating the possibility of well wellbore fractures to their originaL lowdamage and loss of gas to a thief zone. liquid saturatedvalue.

A review of the testproceduresandsubsquent Surface pressure measurementsindicatedthatsampling of returned fluids indicated that the pump out plug opened at about 6,450 psithe original workover water residing in the and tho process from an operationalpoint ofwellbore prier to perforatinghad never been visw went rather smoothly. Figure 14 is aadequatel. PWSI% and tbereforo, both of linear ropraeentationof the surface pressurethese tests had been soriouely cqrcmised measured during tubing pressurization andby the presenc~ of water adjacent to the the impulso injection. Maximum surfacepres-perforatedinte-al. Consequently,thistesting sure can be seen to have been 5,960psi which,sequenco that centered around the use of for a full column of N2, corresponds to apulsed explosivesto create multipl* sets of sand face pressure of about 6,450 psi. Thereunobstructed fracturesthat were de5igned to is a noticeable pressure rate change duringconnect the wellbore and natural fracture the falloff at about 11.2 minuteswhich indi-set could not be considereda valid confirma- catesa significantalterationinflowregimes.tion of the process. Therefore, the tailored Figure15showsthelog-leg/derivativepressurepulse explosive technique still remains a representationof the data for this falloffconceptuallysound stimulationprocedure forthe areals naturally fractured reservoirs.

period.Notethatthere inconsiderablediffer-●nce between this set of cu?wes and thoseforthesimultaneous parforationandN2 break-

N2 robing XDPUMS Ueing a Bcttoabole PUBP down technique employed in MWX-1 and shownout Plug in Figure 11. Xn this case, fractureCr8atiOIi

was most probably not part of the process asFollowingthe attemptedtailoredpulse ●xplo- was the situation fcr the MWIC-10ss.. Thus,sive fracturingtests in14wx-3and the inabil-ity of the well to flow properly a remadal

the fractures in MwX-3 previouslycreated bythe tailored pulsed explosives need only to

treatmentwas considered.This ramedialtreat- be dilatedduringthis processand the trappedment was conceived to mitigate the damqge liquids were disbursed.created by the invading residual wellborewaterthathadbeen inadvertentlybutneverthe- Followingabout48hrsofcontrolled productionlessratherviolentlyinjectadintothenatural andmonitoringgasesusingon siteganchrcmat-fracturesduring the tailoredpulsa explnsive ographic tecbnigues, the well appeared tot8StS. The treatment essentially involved have responded,producing almost 50 MSCFD orapplying a high pressure N2 impulse at the about “65 percent of that produced from theperforated intervalwhen the shear pine in a othertwo wells.!rhus,this remedialtechniquepump out plug located at the bottom ofT~ appears to have sufficient merit to be con-highly pressurized tubing rupture. sidered as a rather inexpensive method tatechniquewasdesignedtodisbursetheresidual clean up near wellbore damage to naturalwater over a larger portion of the fracture fractures.system and thus permit the near wellborefractures to resume their role as relativelyhigh capacityflew paths for reservoirgases. RESULTS ANO CONCLUSIONS

Figure 13 is a schematic of the bottomhole The completion of naturally fracturedreser-configuration.for this remedial treatment.A voixs differs both in substanceand approachtubing packer was set at 5,527 ft, just above from conventional homogeneous reservoirs.the perforated interval with shear pins de- Not only is it reasonably improbable.thatsigned to release the pump out plug at about natural dractures will make their presence6,500 psi. The annulus ?.ndtubing were con- known during drilling,coringorperi?rating,netted together at tb~ surface, and both as shown in the probabilityinterceptcurvee,tubulars were pressurizedusing surface pump but more important,the damage mechanismstctrucks. Pressurizing the annulue served two theseextremelysensitivejointsareso severapurposes; first it acted as a large very thatfractureflowcapacitycouldbediminishec

BREANDOWN PROCEDURESDESIGNEDQ m MXMINIZE NATURALLY FRA~D RESERVOIR DANAGE SPR 17716. . .—. .—.——— ----- ---

to tho point of renderingthem uselessas flowconduits. Once the hypothesis aoncernin9

authorsexpresstheir sincerestappreciation.In paStiOUlw they wish to acknowledge ths

natural fraoturs damage is accepted~ thenintervening completion proaeeses that might

suggestions,dialogueandccntinuoueteohnicalrecomnendationa of Norm Warpineki, Sandia

tend to impair fraoturo flow capacity will NationalLaboratorime,andthetireleseeffortsnc longerba coneidaradacceptablepraotiees. of the entire CER field crew, ●ngineering

Following a number of intermittentsuccessesetaff and computer group. Thanks of aoureeto the DOE, Sandia and CER managamant etaff

and failuresat the MWX that employedconven-tionalparforatingendaqueous-bamtibrduiown

that had the foresight and understanding

techniques, eeveral diffarant non-liquidrequiredtopermitthese ratherunconventionaland often conceptuallyobeoure studiee to be

completionsohameweresuccessfullyperformed.‘rhoresults of these somawhat novel and un-

performed.

orthodox tests are summarizedbelow: Thieworlcwas performedunder contraot016852with Sandia NationalLaboratories,Albuquar-

● High rate pumper injection of N2 alone que, New Maxico, and the U.S. DOE.may notprovideenunambiguousaesesementof its ability to effectivelytreat theentire perforated intezval. NONENCLATORE

● Perforatingin a dry underbalancsdwell- ~ = average reservoir,permeability,mdbore column of N successfullyconneotedthe wellbore wii% the highly .onduotive

kf D ~t~al fra~ure permeability,md

natural fraotures set. ‘j& = averaga reeervoir flew capacity,md-ft .

● N2 Impulse Perforating/NicrofraotUring Lf = fraoture length, ft

using high pressureN2 to simultaneously p = pressure, peicreate fraotures during perforatinghas shown to be field executable as PD = dimensionlesspressure

well as successful in aohieving thedesired wellbore enhancing results.

Dal p = (pressure- initialpressure),psi

p? Group = derivativepressure group, [(tp +

● Tests of a tailored pulse ●xplosive ot)/tpl[(dp/dt)/Dtlteohniquewerecompromieedby thepresanoaof water duringthe tests endthua inter- S = average fracture spacing, ft

&ive resultsareconfinedtoeuccesses Wf . nat~al fracture width, inaxeoutien and operations rather

than a substantive assessment of tach-n = ~oint Roug~ess Coefficient, fraction

nique. pc - capillaryprassura, psi

● A remedial treatment of near wellboreY = interracial T.nsion, dyne/em

and natural fraoturedamage using an NZ oi D in ~itu stresses, pSiimpulsetechniquethat employeda tubingPm out P1U9 prwad to be practicaland successful. REFERENCES

When comparing these techniques to other 1. No*op, D.A., et. al.: ‘Current Statuscompletion sohamae used at the MUX site, of the Multiwell Exparimant,” SPE 12868,indioa:ionachow that N alone can be effec-tively employed in breakdown,microfracturing

presented at the SPE/DOE/GRI UnconventionalGas Recovery Symposium, Pittsburgh,PennsYl-

procedures. FOllOWing these ●xperimental vania, May 13-15, 1984.efforts,the FluvialE res=rvoirwas success-fully interference testad using all three 2. Sattler, A.R.: ‘The MultiWell Experimentwells.Theresultsofthat2-month interferanca Core Program II,* SPE 12854, preeanted attest are presented in a companion paper31 the SPE/DOE/GRIUnconventionalGas Recoveryduring which time an excellentaat of produc- Symposium,Pittsburgh,Pennsylvania,May 13-tion and interference data wera acquired and 15, 1984.analyzed. A great deal of reservoir testingover the past four years at the NWX site 3. Randolph,P.L.: ‘Porosityand Permeabilityunderscore the complexitiesassociatedwith cf Masaverde sandstone Core from tha U.S.understandingcriticalmechanismthat compli- DOE MultiWell Experiment, Garfield COUntY,cate tha effective completion of naturally Colorado,w SPE 11765,presentadattheSPE/DOEfraotured reservoirs. Some of thase damage Iaw Permeability Gas Reeezwoir Sympcsium,procasses are not now entirely obsoure and Denver, Colorado, March 4-6, 1983.can be circumvented using more appropriatetechniques. 4. Branagan, P.T,.G. Cotner and S.J. LOO:

‘InterferenceTasting of the Naturally Frac-ACRNO~S tured Cczzette Sandstone: A Case Study at

the DOE NWX SitO,” SPE 12869, prasanted atThese tests and procedureswere jointly con- the SPE/DOE/GRI UnconventionalGas Recoveryceived and implemented by the NWX project Symposium,Pittsburgh,Pennsylvania,May 13-teohnical staff, and to all of them, the 15, 1984.

..

SPE 17716 P.T. BRANAGAN AND R.H. WIIMER ~

5. Branagan, P.T, St al: ‘Comprehemiv- w@ll 19. Pyraok-Nolto, L.J., ●t al: “HY*ulicTestingandB@dolingofl?re -andPost-FraotureW-11 Porformenccof tlm MWX LentioularTight

md_-f=l=oWfiie80fNat=al FraoturesinLow-PermaabilityRook,‘LBL-22718,L8Wr8nC8

Gas Sands,a SPB 13867, presented at the Berkeley Mboratory, Berkeley, California,SPE/DOI!LowPormeebilityGaSR88SYWOirSSympo- January 1987.slum, Denver, Colorado, May 19-22, 1985.

6.20. Branagan P.T.: ‘Preliminary Results of

‘APIRocomaendedPraotic@Stsnderd~ the N2 FracturingExperiments in tha Coastalfor Evaluationof Well Perforators,”APX RP- Yellow Sandstone,NCER Corporation,Distribu-43, 3rd Ed., API, Dallas (Ootob8r1974). tion Memo, June 19, 1985.

7. Saucier,R.J. andJ.F. Lands:‘Laboratory 21. Warpinski,N.R: “Analysisof ths FluvialStudy of Parforationain Stressed FO-tiOI’I BNitr0g8n Step-Ra.te/Flow-BackTests,wSandiaRocks,m JPT (Sept~er 1978) 1347-1353. DistributionMemo, October 22, 1986.

8. Locke,s.: HAnAdvancedMethod of predicting 22. K~, C.A. and A.B. Yost: ‘practicalthe ProductivityRatio of a PerforatedWell,” Aapeots of Foam Fracturing in the DevonianJPT (December 1981) 2481-2488. shale,” SPE 834S, presented at the 54th SPE

Annual Fall Conference, ms Vegas, Nevada,9. 14cLaod,H.O.: ‘The Effeot of Perforating September 23-26, 1979.Conditionson Well Performance,”JPT (January1983) 31-39.

23. Froaman E.R., et al: ‘A stimulationTech-10. Bell, W.T.: ‘PerforatingUnderbalanced- nique Using Only Nitrogen,m JPT (DSCtierEvolvingTechniques,mJPT (Ootober 1984) 1653- 1983) 2165-2174.1662.

24. Gottsohling, J.C.: ‘NitrogenGasandSand:11. Kelly, T.S.: ‘Discussion of Perforating A New Teohnique for Stimulationof DevonianUnderbalanced - Evolving Teohntques,W JPT Shale,m JPT (May 1985) 901-907.(June 1985) 1065-1067.

25. Branagan, P.T.: ‘Comparisonof Measured12. Howard, G.C., and C.R. Fast: “Hydraulic R8S8rV0ir Pressureswith DrillingHud WeightFracturing,w SPE Monograph Volume 2, SPE data at NWX,” CER Corporation DistributionDallas, Texas, 1970. M-o, January 10, 1987.

13. Jaeger, J.C. and N.G. Cook: ‘Fundamentals 26. Warpinski, N.R.: ‘Analysis of FluVial Eof Rock Meohani.cs,wChapman and Hall, London, Fracturing Experimantat MWX,” SandiaDistri-U.X., Third Edition, 1979. bution Msmo, February 10, 1988.

14. Erbstoeaser,S.R.: ‘Improvedsell Sealer 27. Cuderman J.F.: UD8sign and Modeling ofDiversion,mJPT (November1980) 1903-1910. smallSoaleliultipleFracturingExperiments~.”

Sand81-1398, Sandia National Laboratories,15. Gabrial, G.A. and S.R. Ebstoessar: ‘The 1981.Design of Buoyant Ball Sealer Treatments,”SPE 13085, presented at the 59th AIIXXIal SPE 28. Bourdet, D., et al: ‘A New S8t of TYPeConference,Houston, Texas, September 16-19, curves SimplifiedWell Test Analysis,” world“1984 . oil (May 1983) 9!5-106.

16. Agarwal, R.D., et al: WValUatiOXI and 29. Cinco-L, H., et al: ‘TransientPressurePredictionof Performanceof Low Permeability Analysis for FracturedWells,” SPEJ (AugustGas Wells Stimulattzdby Massive Hydraulic 1978) 253-264.Fracturing,WSPE 6838, preeented at the 52ndAnnualSPESymposium,Denver,Colorado,Ootober 30. Holzhausen, G.R., and R.P. Gooch: ‘The9-12, 1977. Effect of Hydraulic FractureGrowth on Free

Oscillations of Wellbore Pressure,w 26th US17. Amy%, J.W., et al: “PetroleumR8S8rv0ir Sy2tpOSiU on Rock Mechanice, Rapid City,Engineering,”MCGraW-Hill Inc, 1960, 84-85. South Dakota, 621-631.

18. Barton, N., et al: “The Modelling and 31. Branagan,P.T.,eta].:‘Pre-Fraclnterfer-Measuramentsof superconductingRockJoints,m ence Testing of a Naturally Fractured,TightProceedings of the 26th U.S. Symposium on FluvialReservoir,”SPE 17724,to bepreeentadRock Mechanics, Rapid City, South Dakota, at the Gas Technology Sympcxsium,Dallas,June 26-28, 1985, 487-495. Texas, June 13-15, .1988.

SREAKDOWNPROCEDURESDESIGNED10 TO MINIMIZE NATDRALLY PRACTUREDRESERVOIR DAMAGE SPE 17716

/

Figwm 1 An Anrd Wematk of the ThIW MWX WellLocatiom at the Surface and et Dtwti

“crOfm”””\Pv 1.Breakdown/~crofmOture I ~

.-’. Completion

Situ Stress

i“.

‘D-w-FigIm 2 An homatric Dramhg Sbowhg a ConwntionallY4asad Well with I?rrforarions and Bn?akdown#ictv.

fmstum and Concomitant Datnw Along with the 7hs8 h Siw SOW$SVectors in the Hom~naousRock

.

cm? 17716 P.T. BRANAGANAND R.H. WILMER 11

Figura 3 AnMJ V*W of the Conw?ntionally Clunpletad Well S%wn inFigure 2

/“/

N8tutd ‘/“ #-I

FqturaJ r2,ft

Figure 4 A @sad and Perforated Well Similar to &at of Figute 3 Except in a NawrallyFractured Reservoir with Anwaga Frac &acing About Every 2 Ft

,.

BREARDOWNPROCEDURESDESIGNED2 l% MINIMIZE NATURALLY PRACTDRED RESERVOIR DAMAGE SPE 1771{

7’ /-7-

Figwm &% A Cad, t%foratadand MicmfractumdWeJlSimilar to that of Fiwm 3Except in ● Natucdly FRIctumd Resawoir with Awratm FRW SpacingA&u/t Etwry 5 Ft

AL&.-2’ /

/

BmddodMkrofmctllra

Fi@m 5b A Bnukdown/Mkrofi?wlure Inclu&d in the Conc@Xual Well in Figure 5a

?E 17716 P.T. BRANZ4GANAND R.H. WILHER 13

6,s10

S,620

S,630

5,040

5,660

6,560

5,670

02

Fi~m 6

Mwx.1

1

g

1!‘ii!a~

4 6 8 10 12 14 16 18 ~ ~ 24

F*uIro 8@sclnwft

A MonteChloGenaratadW of Probability Cutws for Sawt# Size HolesArbitrarily Pf& in e Naturdlv Friwxut8d Raswvoir with Various Orthogonaland Equally ~ Fraxums

MWX.2 MWX.3

H........../yt.........----f=

5,s10 -

H

..-/“

{.,

S,620 k%......-..—

JS,S20

!

(’ 1“

I <:1‘1 t--a--”l-’l “ml-’-m

Fiqm 7 C?OS &wioni# View of the Thrae MWX Wells and the Location of the Fluvial E Senaatone

EREAKDOWNPROCEDURES DESIGNED1A m MTNIMIZE NM71RkLLY FRACTURED RESERVOIR DAHAGE SPE 17716-. .- .—-.——-— -.--..--—- .- —-—---—— .-.

~----.--..--*8’--T-~~,-““ c---.,‘.

..... .. , t“”,$. .:.’ ,. ... 8 0 82m.... :,.....Isg... .:.. &8aln#o ; : :Fmwu. . ...... ...,.:... .. :..: ~Gum \ t

...... ? \’. R,: .“,” . {... .. . ----.. .

/ ~ .“,,, ,

i .. ....-.

. . . .. .

+ %

-“’, +.,......

“ai-...., .. . .. . . . .. . .. ... .,.: ....... :! ,, ,-.: .,, :.

“:...,.. ,:-’.

“...-. . ..

, . .... ... .,,, ;: ... . $,..,

,. ;, .,: ..8.,,..*; ,:. ... .. . .. . .. ... .. .. . 6,= ft----- -------- -----

---.”- .----Iii!!!?<7G G -:------ .------- -------’ .------ ------- - ..

Fi~~ 8 An ArtI”st%Conception of dw Downhde ConfiWration Duringthe Hi& Pmsum N2 Imptdsa Awforating/M/crof ractutingRoca&ra %rfbrmed in the MWX. ? Wall

x!MN

I

S,31MMWX-1 SurfacaPms9um-

, *Wdhom i

4,* Praulkat&Jn\

3,600 A/ s

2,s00 /

1,s00 // x

690 - /

3.210 i i‘“ U~wX-2B.H. ln~ PmasumI

3,20s

3@2

3,1ss

3,194

3,1901 I I I 1 1 I I 1 I I I -!lm 194 1ss 1% 197 198 1ss m

mm, hrs.

Fi@m 9 tirtsce PMSSUmMeasured in the Hi@ PnQSUm Well, MWX.1, During the N Impulse1’ParfcvatinglMicrofracturing end the Corpsponding Reservoir Interfanmce ressum

attheObsatvation Wall, MWX-2

era A,.*” . . - . ---------- ---- . . . . . ..--—. —-

“%3#N

6

I

3,133

d 3,197dN

~ 3,1%

8,100

I~ 6g300

~

d 4,500e6

2 3,700

Time, minuta

Fi~re tO ExparIdMI 77me &de for Fi~m 10 Detailing the MeasutvdPnHsIresDuring theN2 Impulse Awforating/Microfr@Wrihg

.—

llMloa

H...._l,OW ---Q

8

----- -—.

—.

& -—.-.

I I 111111 I I I I Ill

100

10

Time, minuws

Figure 11 Log-Log/Derivative Curve for the Fracturing PRWSUreAs=ieted witi tie N2 lmPul$QPerforatingAWicmfr~ttiring of MWX- 1

.,

.,

16 TO MINIMIZE NATURALLY FRACTURED nmmmrrmm namaev 12nw**-,.BREAKDOWNPROCEDURESDESKNED

-......-—- .------ .—- .— - . . ---- ----- - w-m 4.1t4w

I

lilt-------------------.-------------.-----------%----.-----------------.----”

--

-3#smfl :“ :-:-g&mm*

.,------- ? -----

----- , . Wa+----

--

.,.,

33M

. .

Ji?l-----------Lti- , :------

---- -IJ:pl tt---- .---- ----------------- .-.

Figws 12 Designed Wellbore Cc@@mtion for the Tailored&la Explw”w in MWX-3

f-a

d$..----.:.,.....=.----’ .: .:...

----- . . . . . . . . . . .

““% ------liil-i;‘: .:.:”.:” ‘------- : ------

“t :;;......--------.. ---------- :..”:.:- --

Itl=-“iuaJti -_-mmPoutPlw- -

Fi~m ?3 Bottomhole Confi~mtion for the t?en#diaiTreatment of MWX.3 Using a Tubing RuptureDisc to (hate a High Pmsu~ N2 Impulse

●

.4

8

SPE 17716 PeTo 8RMAGAN AND R.li.W21HER 17

6,000 ‘.-— —— —.

.- .—

-.. -.— -. . . . .—.

S,ooo —- — --- -.—/ I

—-,-..--

/.— / I——.. —- --— -. -+ .— —..

4,000 --– —- --— .— -/

—. .— . .—...—

/-. -,— /’

/—-

-..— .. -— —---- --- .-- — ..-

.— .

2.000 L 40 2 4 6 8 10 12 14

Fi~m 14 Surface Praswm Date from MWX-3 During dte Pmsurization ofthe Tubing and ~~ent Faiioff Following tie Owing of thaPump Out Rug

Io,ooo

, 1L I 8 1 ,

[ I

II Ill I I 1

, , 1

I I It II I II I 1’1I t

10‘- 0.01 0.1 1 10 100

ThW, Ininums

Fi~re t5 Log-Log/Den&tiw Pm.suIv Qme for MWX-3 Falloff Data Following the Openihgof the N2 Tubing Pump Out Plug