jolley brent faults

8/16/2019 Jolley Brent Faults

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Faulting and fault sealing in productionsimulation models: Brent Province, northern

North SeaS. J. Jolley

1, H. i!"

1,#, J. H. $amens

1,%, &. J. Fisher

', (.

)an*occhi+,

H. (hi"mans1and . Huang

1,#

1Shell UK Exploration & Production Ltd., 1 Altens Farm Road, Ni,

A!erdeen A"1# $F%, UK2Shell nternational Exploration &

Production, 'olmerlaan (, ##(()*+ Ris-i)/0, Netherlands3 "adr

Petroleum ompan2 3"apetco4, 1#5 A!d Ela6i6 Fahm2 Street, 0eliopolis, airo, E2pt

4 Roc +e7ormation Research Ltd,

School o7 Earth Sciences, Uni8ersit2 o7 Leeds, Leeds LS# 9:;, UK 5 Fault Anal2sis *roup, School o7 *eoloical Sciences, Uni8ersit2

ollee +u!lin, "el


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*n general terms, a static hydrocar+on columnheld across a ault is caused +y a/uier and+uoyancy pressure o fuids applied against thecapillary entry pressure o ault rocks and

(u'taposed stratigraphies reaching e/uili+riumacross the ault over geological time Fisher et

al" 21" #his e/uili+rium is achieved atin!nitesimally slo rates o fo, and otenresults in a common static hydrocar+on contactlevel across intra) reservoir aults" oever,under production conditions, press) uregradients +eteen ells induce fo rates ithinthe reservoir sands that can +e much aster thanthe rates achieved across these much loerpermea+ility ault zones" #hus, pressures andthe hydrocar+on saturations and contacts+egin

to separate into compartments across the aults,and +eteen individual sand units foing atdierent rates rom each other across the aultse"g" 6hilds et al" 22" Fault seal analysisunder production conditions thereore attemptsto de!ne the oil, gas and ater rate o foacross the aults in order to /uantiy7 a theeective- connected volumes that can +eaccessed at economic rates +y any given ell8and + the related rate interaction +eteen agroup o ells"

#he tool used or these assessments is the fosimulation or dynamic- model, hich is used inprediction mode- to guide +usiness orecasts,!eld development, production management andell planning decisions e"g" 9ake 21" #he

validity o the prediction mode- o a model istested +y comparing the match

Petroleum *eoscience, :ol" 1% 2;, pp" 321.34 1354);15" g 2; ?0%?=%eological

&ociety of @ondon


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32 S. :. :olle2

Fig. 1. 9iagram shoing the impact o an intra)reservoir ault on fuid fo" a and 5 sho a potentially

unsept compartment, identi!ed in 49 seismic sections and maps red polygon" c Ae)e'amination o the39 seismic data revealed a previously uninterpreted ault, hich mapped out along the curved eastern edgeo the 49 signal" #his coincidence suggested that the ault retarded fo suiciently to act as a seep +arrierin the reservoir" d #he ault as incorporated into the simulation model or the !eld to e'amine its eect onfuid production in three crestal producers, +eing supported +y a donfank ater in(ector" *nclusion o theault dramatically altered the seep pattern" e #he production simulation as improved greatly +y inclusiono the ault . ith the simulated oil and ater rates in the three ells no matching the actual data"


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Fig. #. 6onceptual cartoon o ault transmissi+ilitymultiplier #B calculation +eteen aulted cells o a simulation model" #hese calculations dier indetail +eteen simulation sotare packages andthis particular cartoon modi!ed rom Banzocchi etal" 1


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despite the production history match"6onse/uently, the orecast mode o the model+ecomes increasingly unrelia+le"

#his paper descri+es ho this uncertainty can+e reduced greatly, through the constraints thatare imposed on the model +y inclusion o geologically realistic aults, integrated ith

systematically calculated ault zone propertiese"g" reduced porosity and permea+ility" #he!rst step in ensuring that this takes place is theprovision o a geometrically realistic- horizon)ault interpretation o the seismic data as a+asis to +uild a structurally valid geologicalstatic model" Folloing this, the accurateimport and preservation o the geocellularinormation rom the static model into thesimulation model ensures validity o aultarchitectures and (u'tapositions" #his is, in act,a +asic prior re/uirement or eectivecalculation and integration o aulttransmissi+ility multipliers in the simulator .

since most ault seal)related algorithms are+ased on ault displacement and the propertieso the near)ault stratigraphy see +elo" ethen integrate these geologically valid aultgeometries ith geologically reasoned aulttransmissi+ilities in the simulator . ascalculated rom the upscaled geocellular grid .to produce uni/ue transmissi+ility multipliersor each across)ault cell.cell connection in themodel sensu Banzocchi et al" 1


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Fig. %. a @ocation map and !elds in the $rent Erovince northern #horth &ea8 !elds involved in this studyare indicated in red modi!ed rom nderhill et al" 1


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#riassic structures and older +asementlineaments" #his re) orking o aults toperorm ne kinematic unctions is a commonstructural process e"g" Eeacock C &hepherd1


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Fig. +. 9iagram shoing kinematic linkage+eteen steep thick) skinned- aults and thin)skinned- slump comple'es" a Bap shoing steepaults red lines picked on time)slices and slumpdetachment yello lines picked on .? sectionsand time)slices and an amplitude e'traction romthe ?tive refection, &outh 6ormorant" #hote thatthe steep aults are contiguous ith linearamplitude anomalies in the main +ody o the !eldand that the slump detachment changes dip anddip direction across the steep structures the

yello time)slice picks are e/uivalent to contours"#his indicates that the earlier steep #riassicMaults ere part)reactivated and incorporated aslateral ramps ithin the slump comple'" 5, c.? seismic sections through the slumps, shoing

the linkage +eteen the slumps and local reorkingo the steeper aults"


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Fig. 8. &eismic sections looking north, shoing thegeneral structure o the Eelican Field" &teep thick)skinned aults in the main +ody o the !eld8 thin)skinned slumps at the crest o the !eld8 and thin)skinned slumps ithin the pper eather andKimmeridge at the fank o the !eld" 0lso, noteeastard thinning o the upper $rent se/uencetoards the crest o the !eld" $6, $ase6retaceous nconormity"

ith oset sot)linkage to underlying thick)skinned ault scarps Fig" J" #hese particularslumps ena+le the $ase 6retaceousnconormity to retain a relatively constant,shallo dip across the area o a !eld, eventhough the $rent %roup dip and depth may varyalong)strike" #his is interpreted to indicate thatthey ormed in response to the process o Kimmeridge shales, in particular, slumping andotherise deorming internally to retain acritical angle o slope sta+ility, driven +y ault)

controlled movement o the su+strate +lock tilting, ootall re+ound and uplit during theend Durassic.early 6retaceous riting"

Summar2

+ #he $rent %roup contains a ell)de!nedessentially sand. shale stratigraphic layeringsystem" *n +road terms, this divides the !eldsinto an upper and loer reservoir seriesseparated +y the Bid)#hess)&hale, ithlaterally continuous shale +eds urthersu+dividing the reservoirs into more discretefo units"

+ #he !elds contain a comple' arrangement

o ault (u'ta)positions arising rom a com+ination o linkedsteeply) and shalloly)dipping ault arrays"#hus, sand+ody connectivity and=orcompartmentalization across the aults isthree) dimensionally comple'"

+ #he aults aecting the $rent %roup ereactive during

deposition o some o the later reservoir

units and in the immediate period aterards,

hen eather and Kimmeridge shales ere

+eing deposited" #hus, the aults ere active

hen the $rent %roup reservoirs ere at near)

surace to shallo +urial depths, and ere then

+uried passively ith host stratigraphy to reach

their present)day depth positions"


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H 2 F-4$(S 3)P-/((hS(h923P24/(32N

Fluid fo and pressure in an oil !eld is

compartmentalized +y a com+ination o

stratigraphic and structural architectures"

6urrent su+surace tools and orkfosroutinely include detailed characterization o

the depositional architecture o a given

reservoir, its lithoacies and associated

mineralogical and porosity.permea+ility

property variations" #hese variations are

captured at geological scale ithin the static-

geocellular reser) voir model, and upscaled to

+ecome the fo simulation model or the !eld"

#hus, in siliciclastic reservoirs, stratigraphic

+arriers and +aNes to vertical fo are

captured e'plicitly +y the relatively shale)richlayers in the model and lateral +arriers and

+aNes +y the intra)layer architectures, such as

channels and pinchouts" oever, assessment

and account o lateral fo +arriers and +aNes

at aults is oten incomplete" Fre/uently, it is

assumed that this is entirely due to ault

(u'taposition o reservoir sands ith non)

reservoir stratigraphy" ?ven i time and eort

are given to accurate modelling o valid ault

geometries, the true eect o (u'tapositions on

fo connectiv) ity is complicated +y the act

that there are no clean- (u'ta) positions in

nature" *n detail, a ault plane interpreted rom

seismic data is not a discrete surace . +ut

rather a ault zone- ithin hich the ell)

ordered host stratigraphy is smeared,

disarranged and re)aggregated e"g" Fig" ;8

6hilds et al" 1


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enhances grain)contact /uartz dissolution in theault zone Fig" O8 &verdrup C $(Rrlykke 1


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aults Fig" ;, Fig" O, hich oten havepermea+ilities under "1 S9, +elo that o thesource shale +eds Fisher C Knipe 218?ichhu+l et al" 25" #he moderate to severeporosity.permea+ility reduction that occurs dueto the deormation o impure sands and clay)richlayers may continue during +urial, long ater

aulting has taken place, since the presenceo clay minerals

Structure


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Fig. >. &chematic cartoons o micro)structural processesithin ault rocks, leading topermanent collapse o the host

rock porosity.permea+ilitystructure, as a unction o hostclay content and +urial depth"EFFA, phyllosilicate rameork ault rock"

that the smallest ault thros that can +e imaged+y seismic amplitudes are e/uivalent to 1=4 o the dominant seismic avelength see #onsendet al" 1


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data sho some trendclustering as a unction o+urial depth range o thesamples" d $rent %roup aultpermea+ility as a unction oclay content and +urialdepth o sampled cores" #hered curves represent theupper and loer +ounds o therange o relations that can +ederived rom these data,hilst the +lack curverepresents the hole dataset,and the green and +lue curvesare derived rom su+)sets othe sample depth rangee/uivalent to particular studyreservoirs see te't ordetails"


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segment" *n practice, the dip o refectors and,thereore, any horizons +ased on them, +ecomeunsta+le near to aults in the seismic data, suchthat the horizon terminations are oten raggedand the ault segments they are meant to

terminate against are also oten (ittery in theinterpretation" hilst de)spiking o horizon dataat this stage helps . smoothing o the datadestroys valua+le geometrical inormation e"g"ault thros needed to +uild the static modeland ampli!es gridding insta+ilities ithin thestatic modelling process" #o ensure geometrical

validity and consistency, it is recommended thata structure rameork ault)horizon model is+uilt in con(unc) tion ith the seismicinterpretation, using a rameork +uilding toolspeci!cally designed to model and analysestructural geometries e"g" #heedham et al"1


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internal shape)change to stretch, compress andtist into position ithout opening holes oroverlapping at the corners across the ault planes"Furthermore, aults are not imaged +y seismicrefection data here thros are less thane/uivalent to 1=O to 1=4 dominant seismicavelength see Fig" 11" #hus, the aults in themodel should have coherent, consistent throsenses and should not +e less than c" 1 m herethey coincide ith seismic ault picks" c 0ne'ample o a disconnection +eteen the ault)

horizon geometries ithin the productionsimulation model and the original structure) seismicinterpretation" *n this case the top ?tive suraceith zig)zag tears, has +een e'ported rom thesimulation model into the static model or

visualization in the same 39 space as the seismicinterpretation o aults at the e/uivalent level redault polygons" #here are radical dierences+eteen the to sets o aults and ault thros" #hestatic model aults . not shon here or clarity .have an intermediate geometry"


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Fig. 11. Fault maps romstoped)out areas o a deepgold mine in &outh 0rica,shoing the connectivity o ault patterns as a unction ogeological and seismic throresolution in locally ac/uired39 vi+roseis surveys" a 0ll

geologically mapped aultsdon to practical undergroundorking

resolution, e/uivalent to 1 mstope height" 5 Faults ith1 m or more

thro" c Faults ith 25 m ormore

thro" d 9ierences in aultthro resolution o variousseismic data attri+utes,e'pressed as a proportion o

dominant seismic avelength,as measured directly +yundergroundstructure mapping in deepmines ithin seismic cu+es"

0coustic impedance, re/uency

content etc" alter the e'actrelative thro resolution o thedierent attri+utes, although,in general,to)ay)time osets orefectors image aults donto c" 1=4 o the avelength anddip and amplitude attri+utesdon to c" 1=O o theavelength ater Dolley et al"2;"

o pressure and saturation)fo calculations and,thereore, the overall run)time o a production

simulation" #hus, there is a tension +eteen theto key aims o upscaling7 to satisy the practicalneeds o the simulation +y reducing thegeological comple'ity o a model to its salientcharacteristics8 and to ensure that these keyelements o the geology are preserved during theupscale" #his is, thereore, a process thatre/uires sensitive handling in order to avoiddamage to the plum+ing= fo characteristics o the model" @ateral x>2 upscaling to increasecell size and=or discretize the cells to ormorthogonal grids can cause severe damage to theault geometries and reservoir (u'tapositionsacross them, since it causes idespread changes

to the ault positions, lengths, linkages, throsand surace areas" #his is a particular pro+lemhere +ranching ault arrays may +ecomedisconnected and some aults loop- around theupscaled model" *n severe cases, the reservoirengineer may have omitted pro+lem- aults romthe !nal model altogether" #he impact o

accepting incomplete ault arrays in a simulationmodel is illustrated in Figure 1"

oever, i the static model is +uilt to honourthe rame) ork ault geometries . at a cell sizethat is at or close to the size to +e used in thesimulation model . the model geometry can +etranserred to the simulator ith little or nolateral upscale" #his method preserves thegeometry o the static geocellular ault model" #he+ene!ts o preserving the geologi) cally valid aultgeometries rom seismic interpretation to staticmodel to simulation model in this ay, areillustrated +y the e'ample shon in Figure 13"#his compares the attempts to history matchto simulation models that ere +ased on thesame +asic static model" #he only dierence

+eteen the simulation models is that one aslaterally upscaled damaging


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the geometry, hereas the other astranserred as a realistic- model ithoutgeometrical upscale" #he static model is shonith the top layers removed to reveal therelative position o the aults in the staticmodel ith respect to7 the seismic structurerameork aults that ere used as input data

red polygons8 and the position o thesimulation model ault planes +lack +lades-"#hese models ere run traditionally-, starting

ith simple glo+al ault transmissi+ilitymultipliers, hich alloed an unam) +iguoustest o the eects o ault array and

(u'taposition geometry on the fo simulation"&imulation model 1 Fig" 13a as upscaledlaterally rom the static model +y a actor o our i"e" 25×25 m to 1×1 m anddiscretized, causing ide) spread damage to theault geometries" #he reservoir engineer had atraditional- iterative struggle ith the model

varia+les, hich evolved into a long list o

signi!cant ad hoc edits, including a !ve)oldmultiplier on stratigraphic permea+ility, addinge'tra ault lengths, deleting ault segments andapplying uni/ue local ault transmissi+ilitymultipliers" 0ter more than 225 runs, theengineer as una+le to +ring the model close toachieving a history match and the e'cessive level

o ad hoc edits had undermined con!dence in themodel to measure or orecast productionrealistically" &imulation model 2 Fig" 13+ asderived rom a static model +uilt at there/uired 1×1 m cell size to honour thegeometrically valid struc) ture rameork model, and as transerred to the simulatorithout any upscaling" #his model foedimmediately, ith no permea+ility multipliers onany stratigraphic layers, and only re/uired a eiterations ith a e minor ad hoc edits to comenear to a history match in a+out ; runs,including sensitivity analyses, +eore the e'erciseas stopped"


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Fig. 1#. &tructural validity and consistency +eteen seismic interpretation and static modelling" a $uildand validate a structure rameork ault)horizon model in con(unction ith the seismic interpretation,using sotare speci!cally designed to model and validate structural geometries" 5 *mport the rameork ault polygons into the static model and re)instate the geocellular ault model rom the polygons"

c p)sample the rameork horizon suraces as x. 2 . 6 point data" d *mport these up)sampled point datainto the static model here they should !t snugly +eteen all the aults generated rom the polygons" %ridthe static geocellular horizons rom these data" e 6omparison o the modelled horizons and aults ith theinput data derived rom the rameork model actually a close pro'y or the seismic interpretation shouldsho a strong geometrical correspondence" &tatic model suraces and aults can also +e vieed ithin theseismic domain to con!rm"

SS((h)-(3/ )2(h$$3N6 2FF-4$((-NS)3SS3B3$3(3(hS

0ccurate rendering o ault (u'tapositions ithin$rent %roup reservoir models is critical tounderstanding the +rute connec) tivity o founits" #he permea+ility o ault zones should also

+e modelled, using algorithms +ased on the claycontent o ault rocks, as a +asis or calculatingthe transmissi+ility o aults ithin simulationmodels"

Fault clay content and permea5ility

%iven the relationship +eteen clay content andpermea+ility o ault rocks in $rent reservoirsFig"


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ment mechanisms active ithin the aults +eingmodelled" 0 ull discussion o the advantagesand disadvantages o each method is outsidethe scope o this paper, since all have theirmerits hen used ithin the geological settingsor hich they ere designed e"g" Fisher C

Dolley 2;" *nstead, the algo) rithms used in

the conte't o the ork descri+ed in this paperare summarized"

#he most accessi+le algorithm is the &hale%ouge Aatio- &%A8 Fristad et al" 1


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Fig. 1%. &tatic model surace #op ?tive, together ith rameork model aults derived rom the seismicinterpretation red ault polygon lines that ere used to +uild the static model aults, plus the e/uivalentault suraces rom the simulation model +lack +lades- that ere derived rom them, all loaded into thestatic model or 39 visualization" #his !gure illustrates the +ene!ts o preserving structural geometries romseismic interpretation and rameork model to static model to simulation model" a 6ase 17 #he static modelas upscaled into the simulator, compromising the integrity o the static horizon)ault model and, thereore,the arrangement o (u'tapositions in the model" #his is particularly ell illustrated in the dotted circles,here simulation model aults either link or open inappropriately across rameork ault polygons" #hoproduction history match could +e achieved in more than 225 runs ith this model" #his as despite thereservoir engineer amending ault geometries and treating their transmissi+ility multipliers separately tosteer fo around the model and applying a long list o ad hoc amendments. many o hich e'ceeded geologically reasona+le limits e"g" 5× permea+ility multiplier on all layers in themodel to get it to fo" 5 6ase 27 #he static model as +uilt to honour the ault geometries at the cellsize used in the simulation model no lateral upscaling" #hote that the simulator aults directly overly theoriginal geometrically valid rameork ault polygons" 0lmost none o the previous ad hoc amendments erere/uired in the simulator" For e'ample, model layer permea+ility multipliers ere not needed, and only oneault re/uired ad hoc treatment" ?ach simulation run as a+out 5L aster than the previous model and themodel came close to history match in ; runs, hich included testing various sensitivities, +eore thee'ercise as terminated"

smear, including overlapping o multiple aultstrands across the shale layer" *n crude terms,the clay is s/ueezed like toothpaste rom themore plia+le shale sourcelayers into the aultzone, here it is stretched out as the ault moves

e"g" @ehner C Eilaar 1


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ment o totally sealed and totally open to fo-+ands across the ault planes in a model,+ased on the ratio o ault thro to thicknessdistri+ution o discretely modelled shale sourcelayers" #hereore, these algorithms aree'tremely sensitive to the validity andaccuracy o the modelled layering scheme and

ault thro variations"Pnce displacement +ecomes large enough todisengage smears rom their source layers,they +ecome entrained holly or partiallyithin the ault to +e randomly parked as sandand clay slugs- ithin the ault plane" oever,some outcrop o+servations do not sho asystematic arrangement o clay smears inrelation to their source +eds, and so astochastic approach is used to place- the smeardistri+utions along the ault planes 6hilds etal" 2;" *n situations such as this, and here

the shales are thin ithin dominantly sandstratigraphy or 8ice 8ersa, or sand.shalelayering is relatively !ne cm.m scale, it can +eargued that the smear and slug lengths ill +eup to orders o magnitude less than ault thro

values and are thus accounted or ithin the&%A algorithm once stratigraphy is upscaled"

#his implies that &%A can +e used under theright circumstances as a catch)all algorithm orestimating ault permea+ility e"g" 6hilds et al"2;" oever, in the case o decametre Q1 mscale thickness sand.shale units deormed +ymeso)scale to relatively small seismic)scale aultthros, the ault thro to thickness ratio isithin 4 or 5, so that sand and shale smears aregenerally continuous eatures c" FIrseth2J" nder these circumstances, the aultplane is sealed completely across the shalesmears and stratigraphic continuity


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Fig. 1'. Fault seal algorithms, commonly applied inlo=mid net)to)gross mi'ed sand.shale reservoir

stratigraphies7 a &hale %ouge Aatio &%A, Hielding et al" 1


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ault thros that are e'plicit ithin thegeocellular model construction rom the modelcorner)point x= 2 = 6 and non) neigh+our cellconnection ta+les ith the properties o thestratigraphic layering e"g" net)to)gross, ' shale,

porosity, per) mea+ility" #his calculates uni/ue6&E=&&F and &%A values or each e'plicitly

aulted cell ace in the model" #hese values arethen used as a pro'y or clay percent in order toassign ault permea+ility values derived rommeasured data e"g" Fig"


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ranges +eteen 3"5 and 4" From this, it has +eenpossi+le to use the knon +urial range o a studyreservoir to esta+lish a geologically rationalized+ase case and a high and lo case or aulttransmissi+ility multipliers, derived rom thelocally ac) /uired ault permea+ility data, hichare /uite speci!c to the geological situation o the reservoir under study" #he relations hich !tthe data are +ounded on the lo permea+ility

side +y the parameter pair (a, !)T(1—5

, 3"5) and,

on the high side, +y (a, !)T(1—4

, 4) Fig"


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Simulation results

*t is a general o+servation rom production datathat fuids and pressures ithin fo units in theupper #hess and #ar+ert sands are otencompartmentalized rom fo units in the loer#hess and ?tive sands" hilst depletion is otene'perienced ithin a fo unit over a ider area

than individual small ault +locks,compartments arise during production that are+ound ithin the larger ault +locks in the !elde"g" Fig" 1J" #his preservation o stratigraphiccompartmentalization is e'plained mostlogically +y clay smear processes on the smallerault population as descri+ed a+ove" #he aultsat this scale clearly are not complete +arriers tofo, +ut rather act as fo)retarding +aNes-ithin the individual reservoir layers"

*nitial simulation runs using a traditional-manual application o a ault transmissi+ilitymultiplier o "1 or "2 to all aults in themodel ill oten help provide a starting point

or the engineer to gain a certain level o overallpressure match" #his is more useul in !eldsith a airly homogeneous reservoirstratigraphy, +ut less successul here thereservoir stratigraphy is more heterogeneous"#he results oten indicate that the pressuresithin fo units in the models are too close +ycomparison ith the true layered- and larger

km)scale ault +lock)+ounded pressurecompartmentalization seen in the !elds" #hishomogeneous pressure results rom aults +eingtoo open- and thus alloing potential fo pathsthrough the ault systems here they should +esealed" #hereore, ault transmis) si+ilityreduction is re/uired to achieve a pressure

match +eteen the model and the historicaldata" oever, it is clear that this also induceserrors in the plum+ing- o fo units across theaults, ith some aults +ecoming sealed toomuch in some areas and let too open to fo inother areas" Boreover. and as pointed out +y Banzocchi et al" 1


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Fig. 18. Eressure history maps rom the same time step in production simulation o the #horth 6ormorantField" a &imulation +ased on stratigraphic (u'tapositions alone" 5 &imulation +ased on multipliers derivedrom amalgamated ault permea+ility data c" Figs


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gave overall ater production o 1331 BB$@ atthe +eginning o 24" * the simulation is runith simple ault treatment relying on

(u'tapositions and glo+ally applied single valuemultipliers, then the modelled aterproduction ould have a 143 BB$@ shortall—1";L error" #his as signi!cantly improved

+y applying systematically modelled aulttransmissi) +ility multipliers using local aultpermea+ility data, hich gave only a 23BB$@ ater shortall —1";L error"

Figure 2 shos history match +y aterproduction or one o the platorms in the $rentField" *t indicates that hilst there is animprovement in the history match over simpletraditional ault seal treatment throughapplication o systematically mod) elledmultipliers derived rom amalgamation casedatasets, there is a signi!cant step)change inimprovement o the match here thesemultipliers are calculated rom aultpermea+ility data derived rom this and near+y$rent reservoirs" #he improve) ment isespecially enhanced here these data comerom reservoirs that have e'perienced similar+urial.strain histories" #he multipliers producea clear varia+ility o fuid production across theaults in $rent reservoirs, ith moreheterogeneous distri+utions generated in the

ault)dominated areas o the !elds, and ocusingo fo here previously the seep as moreunrealistically uniorm"

Folloing this stage o applying !eld) andplatorm)scale ad(ustments including thesystematic ault transmissi+ilities descri+edhere, the history matches e have illustrated

ere improved upon urther ith relativelyminor ad(ustments to the models #a+le 1" Fore'ample, some ell locations and perorationdepths are ound to +e in error, such that toomuch ater is in(ected into the inappropriatelayers in the model" #his issue is e'acer+atedhere racturing during ater in(ection acts tore)connect and e/uili+rate depletion o localault=layer compartments in the su+surace +utnot in the model see Fig" 1O" #hese issues areaddressed +y pragmatic ad(ustment to elllocations and perorations, or e'ample, toreplicate the locally anomalous pressure=fuidseep patterns in the model"

3S/4SS32N

#he mature nature o the !elds has provided usith a ealth o structural, stratigraphic andproduction data, suicient to test


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Fig. 1>. &imulated pressure history versus actual pressure history data or to key reservoir cycles founits or 0lpha, $ravo and 6harlie platorms, $rent Field" a, 5 *mperect matches achieved through +estendeavours using traditional- matching methods" c, d %reatly improved !t o the simulation to the data

cloud +y removing all +ut the essential ad hoc amendments and then re)running the simulation again,including systematically modelled multipliers, +ased on $rent %roup speci!c ault permea+ility data" #hisrepresents a step)change improvement in the technical /uality o the history match and the time taken toachieve it" &ome o the local mismatches e"g" around 1


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that a geometrically ro+ust structural staticmodel is translated accurately through theupscaling process"

6alculation o multipliers rom the upscaledcorner)point geocellular grid results in a uni/uemultiplier per aulted cell connection in themodel" 0s such this provides a mimic or the

te'ture- o variation in cross)ault fo +aNingeects that are likely to characterize thesurace o geological aults . as suggested +ythe comple' distri+ution o su+)structures andault rock products ithin natural ault zones"#he overall severity o the +aNing and thedegree o homogenization or granularity in thespatial variation +eteen neigh+ouring mul)tiplier values in this te'ture- is a unction o the&%A.ault permea+ility 7 data relation appliedto the &%A values on the aults"

P the various scenarios tested, those thatcompare &%A ith pu+lished amalgamated aultpermea+ility data are capa+le o improving theproduction history match" oever, a step)change improvement in the match is achieved +y&%A com) parison ith ault permea+ility dataderived rom sources local to the reservoir=!eld

under study in this case, data collected romaults in near+y $rent %roup reservoirs" #heimprove) ment is particularly enhanced hen thedata included are derived rom ault rocksormed under similar +urial depths and hiche'perienced similar +urial stress.temperaturehistories to the study reservoir c" Figs


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ould +e like i lots o dierent +asin types,

stratigraphies and strain.+urial histories ere

com+ined together" #aken in isola) tion, the

moti o each dataset in an amalgamated data

cloud is uni/ue to the local situation, ith only

some +eing similar to the amalgamation

case-" #hereore, as discussed +y Banzocchi et

al" 1


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Fig. #A. Eroduction historymatch measured +y aterproduction or one o theplatorms on the $rent Field"#hote that incorporatingsystematically modelled aulttransmissi+ilities in thesimulation improves the matchto actual production datacompared to the result romthe traditional- approach" Pthe systematic approaches,use o amalgamated ault rock permea+ility data c" Figs


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Fig. #1. 0chieving geometrical validity in seismic

interpretation o horizons andaults and preserving thisgeometry through the staticgeocellular model and into thesimulator" #his is the keystructural sensitivity inachieving a production historymatch since it directly impactsthe plum+ing- o fo unit

(u'tapositions and the aultseal calculation in thesimulation model"


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measured rom aults present in drill coresithin the study reservoir, and=or rom similarreservoirs ithin the same stratigraphy innear+y !elds in the region" #he results areparticularly enhanced here these data are

measured rom rocks that have e'perienced asimilar +urial.strain history to the studyreservoir"

#he results summarized in this paper are a +y)product o our structural ork on live- assetpro(ects during 21.24" #he authors thank predecessors and oice co)ha+itants ho haveorked ith them on these !elds, or their part insupporting this study, in particular &imon Erice,ans de Kei(zer, #im &tevens, and 0drian 6raord,Ao+ &taples, ?ric @eoutre, Dohn ors+urgh, #hirmal

Detha, 0ndy @ind, Eeter atson and 6lair oods"#he &hell authors also take this opportunity tohighlight the +ene!t o colla+oration +eteenourselves in the operating assets and our academic

research colleagues7 Uuentin Fisher ho measuredand provided the ra ault rock property data8 #omBanzocchi and 0ndy eath ho helped ithteething pro+lems applying their #rans%ensotare to our in)house simulation packageBoAe&" 6omments rom revieers %raham

Hielding, &igne Pttesen and #ony $uller helpedimprove the manuscript"

.(hF(h.(hN/(hS

0l)$usa!, $", Fisher, U"D" C arris, &"9" 25" #heimportance o incorpo) rating the multiphase foproperties o ault rocks into production simulationmodels" ?arine and Petroleum *eolo2, ##, 3J5.3;4"

0ydin, 0" C ?yal, H" 22" 0natomy o a normal ault ithshale smear7 implications or ault seal" American Association o7 Petroleum *eoloists "ulletin, >8, 13J;.13O1"

$each, 0", el+on, 0"*", $rock+ank, E"D" C Bc6allum, D"?"1


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9oughty, E"#" 23" 6lay smear seals and ault sealingpotential o an e'humed groth ault, Aio %rande rit,#he Be'ico" American Association o7 Petroleum*eoloists "ulletin, >;, 42;.444"

?ichhu+l, E", 9-Pnro, E"&", 0ydin, 0", aters, D" CBc6arty, 9"K" 25" &tructure, petrophysics, anddiagenesis o shale entrained along a normal ault at$lack 9iamond Bines, 6aliornia . implications or

ault seal" American Association o7 Petroleum*eoloists "ulletin, >?, 1113.113;"Fisher, U"D" C Dolley, &"D" 2;" #reatment o aults in

production simulation models" n@ Dolley, &"D", $arr, 9",alsh, D"D" C Knipe, A"D" eds Structurall2 omplex Reser8oirs. %eological &ociety, @ondon, &pecialEu+lications, #?#, 21


36/37

Eu+lication o the *nternational 0ssociation o &edimentology, 1+, 113.123"

@ygren, B", Fagervik, K", :alen, #"&" et al. 23" 0 methodor perorming history matching o reservoir fomodels using 49 seismic data" Petroleum *eoscience, ?,O5.8, 1J1.11, O8, 13.12J"

Giegler, E"0" 1


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Aeceived 1 #hovem+er 2J8 revised typescript accepted 2O Dune 2;"

jolley brent faults

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