Transcript
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    Laboratory DeterminationLaboratory Determination

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    Conventional Core AnalysisConventional Core Analysis

    Two common methods will be discussed Retort Distillation

     

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     Using this technique, the water and oil saturation can be measured directly.

    Retort Distillation Apparatus

    Retort Distillation ApparatusRetort Distillation Apparatus

    CoresampleHeating

     Water vaporizes first at lower temperature(212ºF), The sample temperature remains at

    º

    Cooling

    e ement

    1000-1100 F

      .

     After Water is vaporized, the retorttemperature increases to 1000-1100 º Fva orizin oil.

    Coolingwater out

     

    Condenser Both water and oil are condensed into a graduatedcylinder

    Record volumes of water and oil vs time  Correct volume of oil for coking and crackingeffectsDetermine volume of water from pores (notcounting water of crystallization from clays)Determine saturations volumetrically

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     Advantages Advantages Rapid (less than one hour)

     

    volumes recovered

     

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    DisadvantagesDisadvantages High temperatures (1,000 - 1,100 °F):

    destroys core sample

    water of crystallization in clays may vaporize –and must be accounted for

    cracking and coking of oil

    cracking is breaking of long chain hydrocarbons intosma er c a n y rocar ons, w c may no erecondensed

    coke is im ure carbon residue formed from oil

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    Determining Water of CrystallizationDetermining Water of Crystallization

    Water from pores is recovered first apparent then estimating waterrecovered from pore space can beinaccurate

    Later, water of crystallization isrecovere at ig er temperatures

    This destroys the core sample

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    Effects of Coking and Cracking of OilEffects of Coking and Cracking of Oil

    Coking and cracking tend to

    Retort Distillation: Scaling Factor for Recovered Oil

    cause only part of oil frompores to be recovered

    We must scale up thevolume of recovered oil tore ec e vo ume o ooriginally in the pores

    Scaling factor depends on API gravity of oil

     

    core sample

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    Retort Distillation CalculationsRetort Distillation Calculations

    measuredw

    w

    V

    S   =   ( )   sourceanother from b p   VV   φ = p

    ( )measuredocorrectiono   VFV   =   ooV

    S   =

    owg   −−=

    correction = o ume correct on actor,

    dimensionless

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    Using this technique the water content is measured directlyand oil content is measured indirectly from the change in

    weight

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    Solvent Extraction ApparatusSolvent Extraction Apparatus

     

    Weigh fresh core sample.

    -

    Condenser 

     core vaporizes, then condenses inthe condenser and falls into the trapwhere water volume is measured.

    Boiling point of solvent must behigher than the boiling point of

    Graduate tube

     Heating rate must be highenough to ensure that

    condensation of water occurs in

    Thimble and core

    Solvent

    t e con enser, so t at waterfalls into the trap.

    Electric Heater 

     the pore space and oil remainsdissolved in the solvent.

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     Advantages Advantages accurate determination of water saturation

    -

    determination of water saturation by solventextraction can be made art of the core sam lecleaning process for small incremental cost

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    DisadvantagesDisadvantages slow (can take several days)

     

    oil remains in solvent

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    Solvent Extraction CalculationsSolvent Extraction Calculations

    wwdryi

    o

    ρVWWV

    −−=

    ww

    VS   =

     p

    ooVS   = Wi = Initial core weight, gm

    Wdry = Core weight after leaching, gm

    Vw = Volume of water collected, cm3

    Vo = Volume of oil, cm3

    Vp = Pore volume, cm3

    ρw = Density of water, gm/cm3

    = 3owg   SS1S   −−=

    o   ,

    ρg = Density of gas is assumed negligible

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     measurementsmeasurements

    Mud FiltrateMud Filtrate

    Hydrostatic Pressure (gas Expansion)Hydrostatic Pressure (gas Expansion)

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     measurementsmeasurements

    Mud FiltrateMud Filtrate

    Hydrostatic Pressure (gas Expansion)Hydrostatic Pressure (gas Expansion)

    Oil base mudOil base mudWater base mudWater base mud

    SaturationSaturation

    WaterWater GasGasOilOil WaterWater GasGasOilOil

    SaturationSaturation

    CoringCoring

    r p o ur acer p o ur ace

     At surface At surface ??

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    REFERENCES:

    -  Ahmed, Tarek : “Reservoir Engineering Handbook-Ch.4:”   , ,Professional Publishing, 2001.

    -  Amyx, James : “Petroleum Reservoir Engineering-Ch.2:Fundamental Properties of Fluid Permeated Rocks”, 1960


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