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What do you know aboutyour reservoirs? The riseof 3D modellingFrom seismic surveys to productionhistory, today’s hydrocarbon indus-try generates huge amounts of datafrom its oil & gas reservoirs. IBMBusiness Consulting Services re-cently estimated that a single oil orgas field can generate on averageup to one terabyte of data per day1.

The organisation of this dataand its transformation into valuabledecision-making information is oneof the industry’s greatest chal-lenges. Get your interpretation ofthe data wrong and bid valuations,new field development plans, and

production estimates will all suffer.The North Sea is a case in

point. Here, reserves have in-creased or decreased by more than50% in more than 40% of thefields2, leading to the requirementto drill 60 to 80% more wells thanoriginally anticipated.

One means of making betteruse of your data is through the cre-ation of 3D models. 3D models area focus for scenario generation, atool to explore possibilities, and aplace to store and analyse informa-tion.

The 3D model is becoming thedefault platform for examining andunderstanding subsurface geology.It improves communication be-

tween colleagues. It allows differ-ent ideas to be evaluated. It pro-vides the reservoir engineer withbetter quantification of the uncer-tainty within the reservoir. Areas ofthe reservoir which require moredetailed analysis can be deter-mined. More accurate assessmentsand predictions of reservoir perfor-mance can be generated. The resultwill be reduced levels of financialrisk.

In order to provide the mostreliable plans for the future, how-ever, it is essential that your 3Dmodel is as accurate as possible, ascontinuously as possible. This accu-racy is vital, since the geometry andproperties of the model determine

A powerful reservoir managementsolution for our times

I OIL AND GAS I TECHNOLOGY I

The 3D model is becoming the default platform for analysis and decision making

By : Elizabeth Thompson, Emerson Process Management, Roxar

1 IBM Business Consulting Services – Meeting the Challenges of Today’s Oil & Gas Exploration and Production Industry.2 The Norwegian Petroleum Directorate, May 2003. 3 Tackling the Oil and Gas Industry Skills Gap, Booz Allen Hamilton, January 2008

This article will take you through the different stages of the 3Dmodelling process and will also look at the crucial role IT and a strong

workflow play throughout.

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where and how big the hydrocarbonaccumulation may be.

This article will take youthrough the different stages of the3D modelling process and will alsolook at the crucial role IT and astrong workflow play throughout.

Developing theproduction planOnce you have found a good pros-pect and proved it with a couple ofwells, the next stage is to develop adetailed production plan.

You need to know how much

actual reservoir there is, where it is,how good the porosity is and wherethe best well locations are for maxi-mum recovery. You also need tohave an accurate idea as to whatwill happen in the reservoir whenyou initiate production.

3D models can provide this in-formation. Emerson ProcessManagement’s Roxar provides anindustry leading reservoir modellingsolution, RMS™, containing state ofthe art tools to conduct, for example,3D uncertainty assessments.

What if the depth conversion isa little inaccurate? What happens if

the water saturation is a little differ-ent? What happens if the net togross is more variable than ex-pected? These are all questionswhich can only be reliably ad-dressed using 3D models.

While there will always be acertain degree of uncertainty inoperator decisions, today’s 3D res-ervoir modelling techniques canbetter quantify these uncertainties,whether they lie in depth conver-sion, structural modelling, geologi-cal property modelling, or dynamicreservoir simulation.

Take RMS™’s property model-ling tools - techniques which com-bine seismic and well data withgeological understanding to gener-ate the most accurate and best con-strained model for describing whichrocks are where. From ‘simple’indicator modelling extrapolatingwell information, to more complexmulti-point statistics which can pro-duce sophisticated geological sce-narios, 3D modelling can ensurethat the full impact of often inde-pendent uncertainties is captured.

Another common challenge isfinding that reservoir performanceis significantly affected by fractures.

Fractures play an im-portant role, bothpositive and negative,in the fluid flowbehaviour of manyfields. They cangreatly enhance thepermeability of rocksand will change thedistribution of flow inthe reservoir throughaltered connectivitypatterns. Their influ-ence can be particu-larly profound in car-bonate fields andbasement reservoirs,where they can criti-cally affect reservoirperformance and bepotentially fatal toindividual wells.

In this context,

The Roxar industry leading reservoir modelling solution - RMST contains state of the art tools toconduct 3D uncertainty assessments

Simulation with the parallelised Tempest can handle multi-million cell models with thousands of wells

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where approximately half of theworld’s proven reserves of oil andgas are in carbonate or fracturedreservoirs, full-field fracture model-ling is essential to gain a clear un-derstanding of how the field islikely to behave. As fractured fieldsalso display a greater potential forvariation in performance throughtime, an up-to-date and accuratemodel is crucial for planning andmanaging long-term field perfor-mance.

Roxar provides an integrated,easy to use fracture modelling pack-age which enables geologists andreservoir engineers to create de-tailed and reliable permeabilitymaps. Using these in flow simula-tion and history matching of reser-voirs to quantify uncertainties al-lows the team to make sensible riskavoidance plans.

The Roxar Fracperm software,which is integrated with the mainRoxar modelling and simulationsuites, combines data, geologicalproperties, geo-statistics and geo-history in a data-driven approach. It isdesigned to make maximum use ofavailable data and allow rapid andinteractive quality control of themodel as it is beingbuilt. It can also linkwith the Roxar historymatching solution,EnABLE™, to provide asingle workflowwhere uncertaintiescan be monitored,their impact assessedand technical effortfocussed where it willmake most difference.

Furthermore,Fracperm’s non-spe-cialist, practical ap-proach means thatthe asset team, whoknow the field best,can build and refinetheir own models.Using advice and QCfrom experts makesmaximum use of both

expert and non-specialist staff andbrings fracture modelling into themainstream.

Once you have a good apprecia-tion of the sub-surface geology, thenext question is where to drill.

RMS™’s well planning toolsallow the geologist to plot and re-fine well trajectories to maximiseextraction, minimise costs andavoid collisions. Proposed wells caneven be included in streamline runsto assess their likely performance.Numerous potential locations cantherefore be proposed and exam-ined in the virtual world beforecommitting time and money to ac-tually drilling.

Hitting the target - real-time adjustmentsOne of the biggest challenges in

reservoir modelling today is thedelay between the analysis andintegration of real-time drilling dataand the updating of the geologicalmodel. Delays can lead to crucialinformation not being available tothe decision-making process as thedrilling takes place.

To meet these challenges,Roxar has developed a real-timegeosteering methodology wherethe continuous flow of availabledata can be smoothly integratedinto the model. Measurement whiledrilling (MWD) and logging whiledrilling (LWD) data is used to evalu-ate the position of the well, assessthe physical properties of the rocksand fluids drilled, and analyse thebehaviour of the drillstring in real-time.

The monitoring of the reservoirconsists of gathering different

Extracting information directly from seismic data greatly increases the power and accuracy of faciesmodelling techniques

FracPerm helps asset teams model their field behaviour without needing external experts to build the model

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types of real-time information, suchas survey data, LWD data, drillinginformation and bottom hole as-sembly information for the differentdrilling phases. All of this data canbe displayed in multiple views incombination with elements of thegeological model.

Roxar’s geosteering functional-ity can then monitor the proximitybetween the bit and objects in themodel. Alarms can be triggeredwhen approaching or exiting prox-imity to objects in the model, forexample, a fault, the reservoir top orthe oil-water contact. The positionof the well under monitoring is au-tomatically quantified within thegeological model with this beingachieved through the continuousreal-time updating and adjustmentof well paths from current positions(real and modelled) and targets.

Locating the position of the LWDtool’s sensors within the geologicalmodel; monitoring in real-time theproximity between the well and ob-jects in the model; and using aworkflow-based approach to updatethe model while drilling: all these al-low the operator to make timely, in-formed decisions, and reduce the riskin well planning and drilling.

And the result for the operator?Improved wellbore stability andhole quality, and optimised wellpaths, leading ultimately to fewer,cheaper and more productive wells.

Managing Mature FieldsManaging a mature field brings anumber of challenges in its ownright. It means dealing with not onlythe geology, but also the impact ofdecisions made when the field wasyoung and less well-understood.

Here a 3D model is vital fordocumenting the history of the field,and building a picture of how theway it has been produced will affectthe way it can be produced in thefuture. The model can examine theimpact of proposed enhanced oilrecovery (EOR) processes, such asgas or water flooding and pressure

support, individual well stimulation,or expected behaviour from the dif-ferent patterns of infill drilling.

The rise of robust and fast res-ervoir simulation and computerassisted history matching - the actof adjusting a reservoir model untilit closely reproduces the observedfield behaviour - has played a crucialrole not only in mature fields butacross the reservoir lifecycle.

History matching, for example,is critical for monitoring displace-ment processes, predicting futureperformance and estimating whereour knowledge of the reservoir isincomplete. It also plays a key rolein developing an integrated ap-proach to reservoir managementbecause it allows the static geologi-cal model to be synchronised withproduction data.

In this way, the rise of computerassisted history matching has al-lowed the engineer to focus on de-veloping an understanding of physi-cal mechanisms active in the reser-voir during production and their rela-tive impact on production behaviour.Powerful statistical techniques canbe used to determine multiple mod-els of the reservoir that will providegood matches to the productionhistory. An analysis of these modelswill, in itself, provide information onuncertain areas or properties.

The history matched results arethen used with the simulator topredict how a field’s future perfor-mance may look and give measuresof the uncertainty about these pre-dictions. In this way, it brings geo-logical modelling and simulationcloser together and provides valu-able information on the economicsof the reservoir.

Improving productionperformance estimatesThe Roxar history matching solution,EnABLE™, is used by operatorsworldwide to gain a better under-standing and measurement of uncer-tainty in reservoir performanceestimates.

EnABLE™ allows the engineerto choose parameters to whichmodel performance may be sensi-tive. Assisted history matching soft-ware can evaluate the impact ofindividual parameters, thereby as-sessing which parameters need tobe changed and exploring how theycould be changed in order toachieve a history match.

The ability to distinguish be-tween critical modelling param-eters, either static or dynamic, andparameters which will have littleimpact on decision-making is cru-cial, allowing resources to be de-ployed efficiently, and ensuring thatpeople can better target the physi-cal assets.

Furthermore, real-time datafrom the field, such as pressure,temperature and flow rates, andother available data, such as seismic,petrophysical and facies updates,are also used to update the modeland quantify structural and reservoirproperty uncertainties in real-time.

The end result is a rapid modelupdating workflow, running on acontinuous basis as new productiondata is gathered. Roxar’s goal is todevelop a ‘big loop’ workflow ofreservoir management that carriesuncertainties and details in the geo-logic model through to simulation.This is now being achieved.

And the recent introduction tothe market of the latest version ofEnABLE™ - EnABLE™ 2.3, will takethis process even further forward.EnABLE™ 2.3 comes with simpli-fied workflows, new and improveddiagnostics, statistical engine ad-vances and better interfaces withreservoir simulators. The result willbe the ability for operators to esti-mate technical and economic uncer-tainty within their reservoirs evenmore accurately and comprehen-sively than previously.

Moving towards a digitalfutureThis article has taken the readerthrough the reservoir modelling,

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simulation and history matchingprocess. At all stages, IT has playeda vital role. Let’s take a look atsome areas.

Firstly, the rise in computingpower has played an integral role increating an enhanced reservoirmodelling workflow.

Distributed computing, im-proved visualisation, collaborativetools and ever more sophisticatedSupervisory Control and Data Acqui-sition (SCADA) systems have allbrought the oilfield closer to thegeoscientist.

The rise in computing powerhas also led to increased efficien-cies within the asset team. Withexpert, experienced personnelscarce and teams frequently spreadacross different countries, the in-creased connectivity of a genera-tion of internet-native geoscientistsallows the sharing of experience asnever before. Collaborative workthrough teleconferencing andshared models is the only way toensure that both deadlines are metand high standards are maintained.In the long run, this sharing of ex-pertise benefits the entire com-pany. Take reservoir simulation, forexample.

The rise of desktop parallelprocessing via the new 64-bit multicore chips, and increasingly afford-able clusters, means that multi-million cell reservoir simulationmodels are now increasingly com-mon. Algorithmic developments,such as single grid dual porositymodelling, and software develop-ments, are all leading to higherresolution, and more accurate, finer-scale simulation of oil and gas res-ervoirs.

The growing accessibility andadoption of reservoir modelling andsimulation on the more generalistengineer’s desktop, has ensuredthat the entire subsurface commu-nity can be involved in creatingthese models and simulation runs,rather than a few, highly specialistreservoir engineers.

A Roxar customer, JohnCampanella from Norwest QuestaEngineering Corp, put it well whenhe said: “Personally, I think reservoirsimulation should be brought downto every engineer’s desktop. Weneed to push simulation out of theback room and into the mainstreamwhere people can use it on a dailybasis.”

By adopting workflows andtools that encourage this distrib-uted-effort approach, organisationsare discovering that they can exploitas yet untapped potential in theirworkforce, involving non-specialistdisciplines and skill levels.

At a time when Booz AllenHamilton3 predicts that up to half ofthe current workforce is likely toretire within the next ten years, suchefficiencies and ‘democratisation’ ofthe reservoir modelling process areto be welcomed.

The importance ofworkflowClosely aligned to the rise in com-puting power is the importance ofworkflow.

From seismic acquisition andinterpretation through to the build-ing of a structural model, fault andfracture modelling, history match-ing and simulation, it is an inte-grated, seamless and collaborativeworkflow which provides the glueto all activities.

Such a workflow is vital as arepository for experience andknowledge, for disseminating bestpractices across global teams, andhelping new staff become profi-cient and efficient in their variousmodelling roles.

A strong, IT-based workflowsimplifies the model building pro-

cess, ensures a high degree of qual-ity control by coordinating inputsand outputs and ensures transpar-ency and accountability through thegeneration of job sequences.

An easy to use interface is alsovital, which is why the latest Roxarreservoir modelling software comeswith a new and modernised userinterface which resembles familiar,everyday software applications.This includes a task pane whichoutlines the kind of tasks users arelikely to want to use at any givenpoint. Seeing what is relevant, as itis required, enhances the user’ssense of control, helps them main-tain their own high standards, andexpands their range of experienceand competence.

A rapid model updatingworkflowImagine a world where reservoirmodels are kept evergreen as drill-ing data arrives, updating in real-time. New production data isequally quickly assimilated throughcontinuous, computer assisted his-tory matching.

The end result is a rapid modelupdating workflow running on acontinuous basis as new productiondata is gathered, ensuring the mostcorrect model is always available formaking important decisions aboutthe reservoir. This is what Roxar isachieving today

At a time when the industry islooking for fast, easy-to-use power-ful reservoir management solu-tions to optimise production fromincreasingly marginal assets, andto make better decisions over theallocation of capital and resources,the timing could not have beenbetter.

Elizabeth Thompson is Technical Information Manager atRoxar, responsible for ensuring that all technical informationis gathered and made available to the marketing and productgroups. Liz was formally product manager for Roxar’s fracturemodelling software and technical product manager forRoxar’s structural geological tools.

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