Exploring for lateral diagenetic heterogeneities in … for lateral diagenetic heterogeneities in...
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Exploring for lateral diagenetic heterogeneities in carbonate systems Being able to predict the scale-dependent characteristics, lateral distribution and connectivity of porosity is key in optimizing production scenarios, notably for Enhanced Oil Recovery (EOR). A typical approach is to assume the porosity/permeability characteristics of carbonates are directly dictated by facies types. Construction of the static geologic model then merely requires distribution of facies types. Vertical facies patterns exhibited in cores and logs condition the model and inter-well facies distributions can be based on the spatial attributes of facies-based sedimentary geobodies, which are inferred from satellite images of modern carbonate facies tracts, derived from geophysical data, or measured on outcrop analogues. However, diagenesis in carbonate reservoirs has a tremendous impact on porosity and permeability. Diagenesis alters rock textures and fabrics, and produces many new diagenetic attributes that can cross-cut depositional facies mosaics. This is the shortcoming of a strictly depositional facies-based approach to carbonate rock typing, because diagenesis can result in complex pore geometries and extensive vertical and lateral heterogeneities in pore network attributes even within depositional facies. In this study, the PhD candidate will explore the lateral variability in diagenetic attributes of reservoir equivalents limestones that crop out to the surface. This will imply first reconstructing sedimentary geobodies at a range of scale, and then do a detailed diagenetic work (thin section, geochemistry, SEM, etc..) on samples taken systematically at the same outcrop. The main objective is to explore for potential trends and geo-rules governing the distribution of early diagenetic textures. Supervisor: Dr Cédric M. John, [email protected]; Group website: www.carbonateresearch.com Minimum requirement for candidates: UG degree in geology, 1 st class, EU/UK citizen, someone who enjoys field work, proficient in English Preferred candidate: all of the above but holding a master’s degree, proven ability to publish papers by being lead or co-author on a paper, experienced with carbonate petrography/diagenesis and fieldwork
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Transcript of Exploring for lateral diagenetic heterogeneities in … for lateral diagenetic heterogeneities in...
ExploringforlateraldiageneticheterogeneitiesincarbonatesystemsBeingabletopredictthescale-dependentcharacteristics,lateraldistributionandconnectivityofporosityiskeyinoptimizingproductionscenarios,notablyforEnhancedOilRecovery(EOR).Atypicalapproachistoassumetheporosity/permeabilitycharacteristicsofcarbonatesaredirectlydictatedbyfaciestypes.Constructionofthestaticgeologicmodelthenmerelyrequiresdistributionoffaciestypes.Verticalfaciespatternsexhibitedincoresandlogsconditionthemodelandinter-wellfaciesdistributionscanbebasedonthespatialattributesoffacies-basedsedimentarygeobodies,whichareinferredfromsatelliteimagesofmoderncarbonatefaciestracts,derivedfromgeophysicaldata,ormeasuredonoutcropanalogues.However,diagenesisincarbonatereservoirshasatremendousimpactonporosityandpermeability.Diagenesisaltersrocktexturesandfabrics,andproducesmanynewdiageneticattributesthatcancross-cutdepositionalfaciesmosaics.Thisistheshortcomingofastrictlydepositionalfacies-basedapproachtocarbonaterocktyping,becausediagenesiscanresultincomplexporegeometriesandextensiveverticalandlateralheterogeneitiesinporenetworkattributesevenwithindepositionalfacies.Inthisstudy,thePhDcandidatewillexplorethelateralvariabilityindiageneticattributesofreservoirequivalentslimestonesthatcropouttothesurface.Thiswillimplyfirstreconstructingsedimentarygeobodiesatarangeofscale,andthendoadetaileddiageneticwork(thinsection,geochemistry,SEM,etc..)onsamplestakensystematicallyatthesameoutcrop.Themainobjectiveistoexploreforpotentialtrendsandgeo-rulesgoverningthedistributionofearlydiagenetictextures.Supervisor:DrCédricM.John,[email protected];Groupwebsite:www.carbonateresearch.comMinimumrequirementforcandidates:UGdegreeingeology,1stclass,EU/UKcitizen,someonewhoenjoysfieldwork,proficientinEnglishPreferredcandidate:alloftheabovebutholdingamaster’sdegree,provenabilitytopublishpapersbybeingleadorco-authoronapaper,experiencedwithcarbonatepetrography/diagenesisandfieldwork
