WELCOME TOCRAIN'S PETROPHYSICAL HANDBOOKPlease be fair to the author. Pay your Shareware Fee HERE and receive a copy of CPH by download.BEGINNER'S GUIDE TO PETROPHYSICSThis Page Beginner FAQ Data Types Uses Visual Log Analysiss Authors ResumeSee Also OrderCPH Publications Courses Site Map BEGINNERS GUIDE TO PETROPHYSICSThis page is intended for people who have little experience in the oil and gasindustry who may be looking at a career path or a university specialty thatcould lead to an interesting and rewarding life. Most of the material here iscovered in other Chapters of this websitebut a few of the basic conceptshave been gathered here to give an overview of the subject of petrophysics.All of my 50+ year career has been involved with the science ofPetrophysics, literally the physics of rocks, in some way or another.Petrophysics is a branch of Geoscience and intimately linked to geology,geophysics, and petroleum / mining engineering. There is no degree grantedin pure petrophysics, so people in this field are often graduates of a closely related specialty and are self-taught fromthere.Petrophysics is mainly used in petroleum exploitation, but also in defining mining and ground water resources.To understand petrophysics, you need to understand rocks and the fluids they contain, how the earths surface andsubsurface change shape, and how pressure, temperature, and chemical reactions change rocks and fluids overeons of time. Thats a tall order.Rocks are formed in several ways, but usually end up as moderately flat layers, atleast initially (mountain building comes later). As successive layers are laid on topof each other, the Earth builds a sequence of rocks with varying physicalproperties. Some layers will have open spaces, called pores or porosity, thatcontain fluids (water, oil, or gas). A rock on Earth with porosity cannot be "empty"-- they must contain something, even if it is only air.

Crain's Petrophysical Handbook - BEGINNER'S GUIDE TO PETROP... https://www.spec2000.net/01-beginnersguide.htm1 of 14 02/07/2015 20:37Rocks that are capable of holdinghydrocarbons in economic quantities arecalled reservoir rocks. Rocks in which the plant and animal residue has notbeen fully converted to useful hydrocarbons are called source rocks. Somerocks are both source and reservoir: others are barren of hydrocarbons, andsome others may act as the trapping mechanism that keeps hydrocarbonsfrom migrating to the surface and escaping.A trap is what keeps oil and gas in the rocks until we drill wells to extract thehydrocarbons. Coal, being a solid, doesnt need a trap to be kept in place.Reservoirs that contain oil or gas also contain water. The quantity of water relativeto the porosity is called the water saturation. In the illustrations, the brown colour issolid rock grains and the space around the grains is the porosity. The black colouris the hydrocarbon and the white is the water, which forms a thin film coating thesurfaces of each rock grain. This is a water-wet reservoir (left). In an oil-wetreservoir, the black and white colours are reversed (right).Finding and evaluating the economics of such reservoirs is the job of teams of geoscientists and engineers inpetroleum and mining companies. A petrophysicist, or someone playing this role, will be part of that team.Once a useful accumulation has been found, drilling, completion, and production engineers take over to put wells onstream. Oil production may initially flow to surface due to the pressure in the reservoir. Some oil pools do not haveenough pressure to do this and need to be pumped. Depending on the reservoir drive mechanism, some wells thatstart flowing will later need to be pumped. Water may be produced with the oil. It is separated and disposed of byre-injection into a nearby unproductive reservoir layer. You cant just dump the water in the nearest swamp. Aquifer Drive -- Before ... and After some productionGas Cap Drive Gas Expansion DriveAn aquifer drive mechanism usually maintains the reservoir pressure for some time but may drop off gradually.Recovery factors vary from 30 to 80% of the oil in place. The oil water contact rises as production depletes the oil. Agas cap drive pushes oil out as the gas expands. Recovery factor is similar to aquifer drive. There may or may not besome aquifer support. the gas oil contact drops as the oil is depleted. Gas expansion reservoirs do not have aquiferor gas cap support. Gas dissolved in the oil expels oil into the well bore because the pressure at the well bore isbelow the reservoir pressure. Recovery factor is awful - usually less than 10%, but this can be improved to maybe20% by injecting water nearby to increase or maintain the reservoir pressure. Water floods, carbon dioxide injection,and re-injection of produced gas or water can be used in nearly any reservoir to improve recovery efficiency.Gas wells do not need pumps, but if they also produce water, a special process called artificial lift is used to get thewater out. That water is also disposed of legally.The economics of a reservoir varies with improving technology. Bypassed reservoirs,discovered and ignored years ago, are now economic due to technical improvements indrilling practices and reservoir stimulation techniques. Horizontal wells and deep waterdrilling are now common. The use of heat or steam to assist production of heavy oil orbitumen, and multi-stage hydraulic fracturing to stimulate production in tighter reservoirsare relatively new techniques and relatively economic today. Obviously the specific priceof oil or gas after delivery to the customer plays an important role in how much effort canbe expended to recover oil and gas from underground.There is controversy, of course, about new technology. Just as the Luddites resisted the weaving machines in theearly 1800s, modern Luddites insist that the old ways of oil and gas extraction are best, while at the same timecomplaining loudly about the price of gasoline at the pumps or the cost of electricity for their air conditioners. Youcant have low-cost and low-tech at the same time.Crain's Petrophysical Handbook - BEGINNER'S GUIDE TO PETROP... https://www.spec2000.net/01-beginnersguide.htm2 of 14 02/07/2015 20:37Green alternatives are 50 to 100 years away. Every green technology needs oil to make the required plastics and fuelthe manufacturing and delivery systems. The electricity grid is far too fragile to fuel extensive use of electric vehiclesanywhere, let alone everywhere. And where would all that electricity come from (coal?). Clean coal is moreoxymoronic than military intelligence. So if you and the other 7 Billion people on this planet want to live acomfortable life, get used to oil and its risks. Staying in bed is risky too -- more people die in bed than anywhere else.For the record, Ive been off the grid with wind or solar since 1984. But I live in the middle of nowhere so the estheticsdont bother the neighbours. What have you done to green-up this world?BASIC PETROPHYSICS"Last week, I couldnt spell Petrophysicist. Now I are one." That describes me in 1962as I moved from Montreal to Red Deer, Alberta to run well logs for a company calledSchlumberger. The word petrophysics had been coined 20 years earlier by a geologistnamed Gus Archie and it wasnt used much back in the day. Lately it has attained acertain cachet, denoting a professional level career path.What is a "well log" you ask. It is a record of measurements of physical properties ofrocks taken in a well bore, usually drilled for oil or gas, but possibly for ground wateror minerals. Think of a ships log. The first record of such a log dates back to 1846when Lord Kelvin measured temperature versus depth in water wells in England, fromwhich he deduced that the Earth was 7000 years old. The fact that he was wrong is notimportant. Log analysis is an imperfect science.Illustration of a wireline logging job: logging truck with computer cabin, cable andwinch (right), cable strung from winch into drilling rig derrick and lowered into borehole, with logging tool at the end of the cable. Logs are recording while pulling the toolup the hole. Logs can also be run with special tools located at the bottom of the drillingstring, or conventional tools can be conveyed on coiled tubing or drill pipe ==>The first logs for oil field investigation were run by the Schlumberger brothers, Marceland Conrad,in 1928 in Pechebron, France. Soon, the service migrated to North andSouth America, Russia, and other locations in Asia. At that time, the only measurementthat could be made was of the electrical resistivity of the rocks. High resistivity meantporous rock with oil or gas, or porous rock with fresh water, or tight rock with very lowporosity. Low resistivity meant porous rock with salty water or shale. Take your pick.Local knowledge helped.One virtue of the well log was that the top and bottom of each rock layer could bedefined quite accurately. When the log and depths were compared to the rock samplechips created by the drilling process, a reasonable geological interpretation might bepossible, but was far from infallible.By 1932, the spontaneous potential (SP) measurement was added. The analysis rulesexpanded: low SP meant shale, or tight rock, or fresh water. High values meant saltwater with or without oil or gas in a porous rock. The resistivity could then be used to decide on water versushydrocarbons. Perfect. Except there were lots of shades of grey and the SP was not always capable of defininganything.Crain's Petrophysical Handbook - BEGINNER'S GUIDE TO PETROP... https://www.spec2000.net/01-beginnersguide.htm3 of 14 02/07/2015 20:37Logs from 1932 in Oil City-Titusville area, Pennsylvania, the location of Edwin Drake's "First Oil Well" (in the USA - 6other countries had oil wells predating this one). His well was only 69 feet deep, so it penetrated just to the top ofthese logs, which found deeper and more prolific reservoirs. Each pair of curves represents the measured dataversus depth for one well. The SP is the left hand curve of each pair; deflections to the left (shaded) show porousrock. The resistivity is the curve on the right of each pair. Deflections to the right (shaded) show high resistivity, andwhen combined with a good SP deflection, indicate oil zones. Some good quality rocks in this example do not havehigh resistivity and are most likely water bearing.The gamma ray log appeared in 1936. The rules were easy: low value equaled porous reservoir or tight rocks. Highvalues were shale. It said nothing about fluid content.By 1942, Gus Archie had defined a couple of quantitative methods that turned analysis into a mathematical game,instead of just some simple rules of thumb. His major work established a relationship between resistivity, watersaturation, and porosity. If we knew porosity from rock samples measured in the lab, and a few other parameters, wecould calculate water saturation from the resistivity log values. This was really new news.He even attempted to calculate porosity from the resistivity log. This worked in high quality (high porosity) reservoirsbut had problems in low quality rocks or heavy oil.Just after 1945, a method that investigated theresponse of rocks to neutron bombardmentbecame available. The neutron log was the firstporosity indicating well log. High values meantlow porosity or high porosity with gas. Lowvalues meant high porosity with oil or water, orshale. Add the gamma ray log, SP, and resistivityand again the world was perfect, except for allthose shades of grey. Calibrating the response toporosity depended on a lot of well boreenvironmental parameters (hole size, mudweight, temperature) so it was not terriblyaccurate.It wasnt until 1958 that the measurement of thevelocity (or travel time) of sound through rocks ina well bore was achieved. It turned out that thetravel time was a linear function of porosity and aCrain's Petrophysical Handbook - BEGINNER'S GUIDE TO PETROP... https://www.spec2000.net/01-beginnersguide.htm4 of 14 02/07/2015 20:37few other factors.

Mainframe computers and dumb terminals were reallyunfriendly environments. It was apparent that some portable form of computer was needed to do the math and makepretty images of our results to show to management and team members. Five years before the IBM-PC, the HP9825calculator became a computer and LOG/MATE, "The Friendly Log Analysis System", was born (1976). Today, far moresophisticated and powrerful systems are commont, but LOG/MATE was the first.Crain's Petrophysical Handbook - BEGINNER'S GUIDE TO PETROP... https://www.spec2000.net/01-beginnersguide.htm5 of 14 02/07/2015 20:37Advertisements for my two major forays into the software business: LOG/MATE 1976 (left), META/LOG (1986)We now call the business "Integrated Petrophysics" because we use much more than log data to get our answers.Lab data from core analysis, such as porosity, permeability and grain density, are critical input parameters used tocalibrate our work. More exotic lab measurements have become more common as we move into unconventionalreservoir types like shale gas and tight oil prospects.TYPES and USES OF WELL LOG and LABORATORY DATAThe table below might not mean too much to someone who is not in the oil and gas business, but it will giveeveryone an idea of the scope of work, wealth of data types, and the multiplicity of uses that petrophysical datacanbe applied to.DATA USES -General OutlinePetrophysical AnalysisGeophysical ApplicationsGeological ApplicationsDrilling ApplicationsEngineering ApplicationsCompletion ApplicationsProduction ApplicationsDATA USES - Petrophysical AnalysisShale ContentPorosityLithologyWater SaturationMovable HydrocarbonIrreducible Water SaturationWater Cut / Relative PermeabilityPermeability / ProductivityFracture Intensity / OrientationFluid Contacts - Original and DatedProductive IntervalsSwept ZonesPore Volume / Hydrocarbon Pore VolumeFlow Capacity"Net Pay"Where Are The Reserves?DATA TYPES General OutlineSeismicMagneticsGravityRadiometricsAir / Satellite ImagesWell History Tops, Tests, Cores, Perfs, Logs, StatusLogs - Many VariationsCores - Many Types of AnalysesData Gathering ConsiderationsData DigitizingProject PlanningQuality ControlDATA TYPES - ENGINEERINGFluid PropertiesPressure TransientWellhead / Bottomhole PressuresProduction HistoryInjection HistoryCompletion DiagramFacilities In Place / NeededEconomics / Costs / PricesDATA TYPES While DrillingSample DescriptionsCrain's Petrophysical Handbook - BEGINNER'S GUIDE TO PETROP... https://www.spec2000.net/01-beginnersguide.htm6 of 14 02/07/2015 20:37How Much Does This Well Contribute?DATA USES - Geophysical ApplicationsVelocity and DensitySeismic Modelling ?Synthetic SeismogramsEditing Logs for Seismic Bad Hole Condition Invasion Missing Log DataModeling Hypothetical Rock SequencesModeling Hypothetical Fluid ContentVertical Seismic ProfilesSeismic While DrillingCalibrating Seismic InversionCalibrating Seismic AttributesAmplitude versus Offset ModelsIs the Seismic Interpretation Realistic?DATA USES - Geological ApplicationsReservoir DescriptionStructure and StratigraphyDip and DirectionSedimentary ModelsSequence StratigraphyBedding Type / OrientationMineralogyDepositional EnvironmentTectonic StructuresSedimentary StructuresMulti-well AnalysisCross Sections / Fence Diagrams3-D VisualizationCorrelation and MappingGeostatistics Conventional FractalWhat Are the Geologic Risks?DATA USES - Drilling ApplicationsDesigning Vertical WellsDesigning Deviated WellsDesigning Horizontal WellsDrilling PrognosisOverpressureStress Regimes / FracturesBorehole StabilityBit SelectionCost EstimatesWhere Are The Drilling Risks?DATA USES - Engineering ApplicationsCalculating ReservesCalculating ProductivityCalculating Cash FlowReservoir Simulation / ModelingHistory MatchingProduction PredictionDrilling RecordsMud LogsCore DescriptionsMeasurements While DrillingLogging While DrillingSeismic While DrillingDATA TYPES After DrillingConventional Open Hole LogsImage LogsThin Bed Tools and ProcessingPetrophysical Analysis ResultsGeological Correlations / MapsSeismic Analysis / VSPTest ResultsCore Analysis ResultsDATA TYPES - Open Hole LogsResistivity and Resistivity ImagingAcoustic and Full Wave AcousticNatural and Spectral Gamma RayFormation Density and Litho DensityNeutron PorosityDipmeter and Deviation SurveysFormation Imager and TeleviewerElectromagneticNuclear Magnetic ResonanceInduced Gamma Ray SpectroscopyPulsed Neutron and ActivationPressure Profiles / Sample TakerSidewall CoresDATA TYPES After CompletionCased Hole LoggingReservoir Description LogsProduction LogsCasing / Cement Evaluation LogsBottom Hole Pressure SurveyWell Test ResultsInitial Production / AOF / IPRDATA TYPES Special CasesHorizontal / Deviated WellsLogging Through Drill PipeCoiled Tubing LoggingDATA TYPES Core DataConventional Core Analysis Permeability, Porosity, Saturation Grain Density Lithology DescriptionSpecial Core Analysis Electrical Properties Capillary Pressure Relative Permeability Thin Section Petrography Scanning Electron Micrographs X-Ray Diffraction Infra-red MineralogyCore Imaging White Light Ultra Violet LightCrain's Petrophysical Handbook - BEGINNER'S GUIDE TO PETROP... https://www.spec2000.net/01-beginnersguide.htm7 of 14 02/07/2015 20:37Production OptimizationEconomic AnalysisIs The Well/Pool/Project Any Good?DATA USES - Completion ApplicationsPerforating IntervalStress Regime / OrientationHydraulic Fracture DesignAcidizing / Other TreatmentsSand ControlMaximize ProductivityAre There More Targets?Is production maximized?DATA USES - Production ApplicationsThrough Casing Reservoir DescriptionFluid IdentificationCement EvaluationCasing InspectionFlow and Production AnalysisGas Leak DetectionHow Do We Repair The Well? X-Ray CT ScansDATA TYPES Fluid PropertiesDensity, ViscosityWater Resistivity, Chemical AnalysisOil / Gas AnalysesDATA TYPES Pressure TransientPressure versus TimeBuildup or DrawdownHorner / Ramey PlotsPBU Modeling / Curve FittingStatic Wellhead PressureStatic Bottom Hole PressureDATA TYPES Production DataOil / Gas / Water RatesChanges With TimeCompletion HistoryWell / Pool / Reservoir SummariesDeliverability Analysis ResultsBASIC VISUAL ANALYSIS OF WELL LOGSI have been teaching the practical application of petrophysics since 1967. The seminars always start with "What is alog?" and "What do we do with them?". The first question was answered in the previous section. Here, Ill try toprovide an answer to the second, just as it s done in the seminar. We use the rules as developed over the last 80years and apply them to the individual log curves as we see them on paper or on a computer screen.The step by step procedure using Crains Rules will reduce the complexcity considerably and give you a straightforward path toward your goal. The illustration below is to give you a few of the basic rules in one single illustration.Further on there is a more detailed coverage of the Rules.Lets start with just 3 curves - the gamma ray (GR),resistivity, and a porosity indicating log (a sonic inthis example). The GR is at the far left and thesonic is the left edge of the red shading. Theresistivity and sonic have been overlaid to make iteasier to see the shape of the two curves relativeto each other.Basic Rule "A": When GR (or SP) deflect to the leftthe zone is clean and might be a reservoir qualityrock. When GR deflects to the right, the zone isusually shale (not a reservoir quality rock). Thereare exceptions to this rule, of course.Basic Rule "B": Porosity logs are scaled to showhigher porosity to the left and lower porosity tothe right. Clean and porous is good, so comparethe GR to the porosity log and mark clean+porouszones.Basic Rule "C": Resistivity logs are scaled toshow higher resistivity toward the right. Higherresistivities mean hydrocarbons or low porosity.Crain's Petrophysical Handbook - BEGINNER'S GUIDE TO PETROP... https://www.spec2000.net/01-beginnersguide.htm8 of 14 02/07/2015 20:37Low resistivity means shale or water zones. Soclean+porous+high resistivity are good. There areexceptions to this rule too.The exceptions are what makes the jobinteresting. There are low resistivity pay zones,radioactive (high GR) pay zones, gas shales, oilshales, coal bed methane, and low porosity zones that produce for years. Some of these are shown in the illustration.See if you can figure out the logic behind each of the interpretations shown here before you move on to the moreformal rules.The more detailed Crains Rules are described here with reference to the logs shown below.Crains Rule Minus 1: Identify log curves available, and determine their scales.The left half of this image shows a resistivity log with spontaneous potential (SP) in Track 1 and shallow, medium,and deep resistivity (RESS, RESM, RESD) on a logarithmic track to the right of the depth track. The right half of theCrain's Petrophysical Handbook - BEGINNER'S GUIDE TO PETROP... https://www.spec2000.net/01-beginnersguide.htm9 of 14 02/07/2015 20:37image shows a density neutron log with gamma ray (GR) and caliper (CAL) in Track 1. Photo electric effect (PE) is inTrack 2 with neutron porosity (PHIN) and density porosity (PHID) spread across Tracks 2 and 3.Crains Rule #0: Gamma ray or SP deflections to the left indicate cleaner sands, deflections to the right are shaly.Draw clean and shale lines, then interpolate linearly between clean and shale lines to visually estimate ShaleVolume (Vsh).To find clean zones versus shale zones, examine the spontaneous potential (SP) response, gamma ray (GR)response, and density neutron separation. Low values of GR, highly negative values of SP, or density neutron curvesfalling close to each other usually indicate low shale volume. High GR values, no SP deflection, or large separationon density neutron curves normally indicate high shale volume.Very shaly beds are not Zones of Interest. Everything else, including very shaly sands (Vsh < 0.50) and evenobvious water zones, are interesting. Although a zone may be water bearing, it is still a useful source of log analysisinformation, and is still a zone of interest at this stage.Crains Rule #1: The average of density and neutron porosity in a clean zone (regardless of mineralogy) is a goodfirst estimate for Effective Porosity (PHIe).Crain's Petrophysical Handbook - BEGINNER'S GUIDE TO PETROP... https://www.spec2000.net/01-beginnersguide.htm10 of 14 02/07/2015 20:37Crains Rule #2: The density porosity in a shaly sand is a good first estimate for Effective Porosity (PHIe),provided logs are on Sandstone Units.For zones of interest, draw bed boundaries (horizontal lines). Then review the porosity logs: sonic, density, andneutron. All porosity logs deflect to the left for increased porosity. If density neutron data is available, estimateporosity in clean sands by averaging the two log values. In shaly sands, read the density porosity. IMPORTANT: Thisis just an estimate and not a final answer.Scale the sonic log based on the assumed matrix lithology. Mark coal and salt beds, which appear to have very highapparent porosity. Identify zones which show high medium, low, or no porosity. Low porosity, high shale content,coal, and salt beds are no longer interesting.Crains Rule #3: Tracking of porosity with resistivity on an overlay usually indicates water or shale.ORLow resistivity with moderate to high porosity usually indicates water or shale.Crains Rule #4: Crossover of porosity on a resistivity log overlay usually indicates hydrocarbons.Crain's Petrophysical Handbook - BEGINNER'S GUIDE TO PETROP... https://www.spec2000.net/01-beginnersguide.htm11 of 14 02/07/2015 20:37ORHigh resistivity with moderate to high porosity usually indicates hydrocarbons.Raw logs showing resistivity porosity overlay. Red shading indicates possible hydrocarbon zones. The density ordensity porosity (solid red curve) is placed on top of the deep resistivity curve (dashed red curve). Line up the twocurves so that they lie on top of each other in obvious water zones. If there are no obvious water zones, line them upin the shale zones. If the porosity curve falls to the LEFT of the resistivity curve, as in Layers A and B, hydrocarbonsare probably present.To find hydrocarbon indications and obvious water zones, compare deep resistivity to porosity, by mentally orphysically overlaying the density porosity on top of the resistivity log. High porosity (deflections on the density log tothe left) and high resistivity (deflections to the right) usually indicate oil or gas, or fresh water. See red shaded areaon resistivity track on the log above.Layer A above is a shaly sand and has medium porosity. Layers B and C are clean sands and have high porosity. Allother layers are shale with no useful porosity.Crain's Petrophysical Handbook - BEGINNER'S GUIDE TO PETROP... https://www.spec2000.net/01-beginnersguide.htm12 of 14 02/07/2015 20:37The average of density and neutron porosity in Layers B is 24 %; Layer C is 19%. This is close to the final answerbecause there is notmuch shale in these zones. The average in Layer A is 16 % - much higher than the truth due tothe influence of the shale in the zone. The density porosity is about 11%, pretty close to the core data. Therefore allour analysis must make use of shale correction methods.Low resistivity and high porosity usually means water, as in Layer C. Known DST, production, or mud log indicationsof oil or gas are helpful indicators.Layer B and Layer A show crossover when the porosity is traced on the resistivity log, so these zones remaininteresting. In fresher water formations, it is often difficult or impossible to spot hydrocarbons visually. If it was easy,log analysts would be out of work!Crossover on the density neutron log sometimes means gas (not seen on the above example). Watch for rough holeproblems, sandstone recorded on a limestone scale, or limestone recorded on a dolomite scale, which can also showcrossover not caused by gas.Water zones with high porosity and low resistivity are called obvious water zones. Fresh water may look likehydrocarbons, particularly in shallow zones. The lack of SP development will often help distinguish fresh waterzones. Low porosity water zones may not be obvious.Crains Rule #5: Approximate Water Saturation (SWa) in an obvious hydrocarbon zone is estimated from:SWa =Constant / PHIe / (1 - Vsh)where Constant is in the range from 0.0100 to 0.1200.Use 0.0400 as a first try in sands, 0.0600 to 0.0800 in shaly sands, and 0.0250 in intercrystalline carbonates.Water saturation is usually calculated from the Archie equation or a shale corrected version of it. This is not easy todo with mental arithmetic. An easier estimate of water saturation can be made in obvious hydrocarbon zones byusing a method attributed to Buckles, and it is commonly used by reservoir engineers in a hurry.Here is the computer output from thedata in the logs used in the visualanalysis shown above. ==>This depth plot is typical of a straightforward petrophysical analysis. Someraw data curves are presented becausemost people find them helpful incorrelating the zones of interest. Fromleft to right are gamma ray (GR),spontaneous potential (SP), then threedifferent resistivity curves (RESD, RESM,RESS) with the depth numbers inbetween them and the GR / SP track.Next come some answers, from left toright, water saturation (SW), porosity(PHIe), permeability (Perm), and themineral breakdown on the right. Thislatter track shows only shale and quartzin this example.The solid red shading in the porositytrack is the oil in the porosity. More redis good news. The white area to the rightof the oil is the water volume in thereservoir.Crain's Petrophysical Handbook - BEGINNER'S GUIDE TO PETROP... https://www.spec2000.net/01-beginnersguide.htm13 of 14 02/07/2015 20:37Using the curve colour codes and scalesat the top of the log, you can identifyeach curve and read values for theanswers. For example the upper oil zonehas about 10% porosity, 40% watersaturation. The zone is 50-60% shalewith the balance being quartz.The lower oil zone has 24% porosity,17% water saturation, nearly zero shale.The white area underneath the red,indicates a watrer zone under the oilzone.Coloured dots represent lab analysisdata for [orosity and permeability. Theclose agreement with the log analysismeans we did a good job. This may havetaken a few iterations to get all theparameters just right.MORE ADVANCED STUFF: There aremany more rules of thumb, someuniversal, some more local, that areused in visual log analysis. These arecovered elsewhere in this Handbook. Allof them have been quantified by usingequations that relate log readjngs and parameters selected by the analyst to obtain reasonably accurate quantitativeanswers, provided there is some "ground truth" such as core analysis data, production history, sample descriptions,etc, to give us some comfort that the answers really are reasonable. RAM. IBM didn't "invent" the PC until 1981.SITE NAVIGATIONCrains Petrophysical HandbookOn-Line Handbook IndexPay Shareware FeeOrder Handbook DownloadDownload Free SpreadsheetsDownload Free PublicationsWebsite TestimonialsAbout The AuthorTerms of UseWhats New or UpdatedPetrophysical Training CoursesCourse DatesCourse OutlinesAudio-Visual CoursesReference ManualsBecome An Associate InstructorSingle-User, Corporate, Academicand Associate Instructor LicensesAre AvailablePetrophysical ServicesConsulting ServicesClient ListProject ListFree PublicationsSearch This SiteContact UsDesign and Content Copyright 2015E. R. 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